GStwin.com GS500 Message Forum

By changing the stock gearing from 16/39t to 17/35t you can drop quite some rpms on the highway.
Doing so, i had to get a 108 link chain, as even the stock 110 link would bring the adjustment all the way to the end, with no room left for adjustments.

Initially I had bought a 106 link chain, but it barely fit the 35t rear, and I couldn't get the 17t front on it. The bike rode quite fine, though gears where still a bit short.
When I say short, I mean that the bike'sgears are tuned for gear shifting at 4-8k rpm range. A drop of 1000rpm shifting in that range, only means a drop of half that RPM when shifting in the 2-4k rpm range.
Most of the time, I try to ride moderately,  between 3-6k rpm shifting, and thus I need longer spacing between the gears.

That, and the fact that most of my riding is between 35 and 50mph, and I want to do that in final gear, with an as low rpm as possible.

So for that purpose, combined with a good sprocket and chainlink ratio, I calculated that I would need. 17/35t setup.
The 17/35t work excellent on a 108link chain.

However, a 17/35t does have 2 inherent problems:
1- being that idling in 1st gear gets the bike going at almost 6mph. Not fun in traffic, and sometimes feathering the clutch is needed in start-stop traffic and uphill.

And 2- that it's hard to get the bike past 80mph in final gear.
Ducking forward, over a good minute or so the bike does finally get to 105mph indicated. It just shows me that the bike has enough power, but barely.

For that, a 17/36t would give me the power to get to 105mph indicated a lot faster, since the bike will have higher HP with the 300rpm higher revs at those speeds, and have a tad higher torque to the rear wheel as well.

So from a performance point of view, a 17/36t makes most sense.
The only problem I'm facing, is that with a 108 link chain, the rear sprocket will wear out the chain (or reverse). Sprocket/chain ratio couldn't be worse.
With the stock 110 link chain, the rear wheel chain adjustment will be close to the end, but it'll still be ok! Also chain-link/sprocket wear is quite good!

Another inheritent problem I've noticed, is that changing the gear ratio, somehow affects the air/fuel mixture.
The bike has no problems going WOT in 4th or even 5th gear, but 6th gear with the 17/35t, the engine load is different, and I have the impression that I need to get a bigger main jet. It is funny to note, that these problems are almost non-existent with the stock gears, or running 80+ mph at 7+k rpm.
They do appear when doing the same thing at 5k rpm.

A 17/36t has less of a problem than a 17/35t with the af ratio (and the throttle losing power the last 10-20%).
It gives the hair more power the engine needs to get to top speed of 105mph indicated, without over revving the engine, and still allowing to reach 112+ mph top speed indicated, in 5th gear at 8700rpm.
It also has less problems with low rev engine vibrations. A 17/35t can't get rpm lower than 2750rpm or the engine will give odd vibrations. A 17/36t might bring that down to 2600rpm.

Anyone (esp. new riders) reading this later: MeeLee here does what many like to call "hypermiling".
You don't want to start experimenting with a GS you have just bought.
You don't want to lug a high-revving (for a twin at least) GS engine.
The stock gearing is just perfect for ~95% of GS riders, 6th already being an overdrive gear.
I'd advise anyone not to start messing with the stock gearing until they have ridden the bike at least 10k kilometres (~6k miles).

For someone interested in hypermiling, this is good information.
YMMV, peace :thumb:

I went 17/39 and could get 65 Mpg any day of the week on the open road, once I got 69.8 Mpg not even trying. What are you trying to do here?

A jetting problem that only exists in 6th? .. isn't that called wind resistance?

You are right on with your reply to Mr. Lee....

Mr. Lee is insane....

Lugging and engine is just about the worst thing you could possibly do.

The only gear ratio that would have anything to do with mileage is 6th....as you said, 6th is already a very high gear for the GS (like an overdrive)...but going to a high gear and low RPM will not necessarily give better mileage......if you are over geared, you need wide throttle to accelerate...this will cause bad mileage...

the way to get good mileage on the GS 500 is to use the throttle wisely...smooth accelerations without full wide open throttle...keep the speed down to 50 or 55 mph.....

Faster speeds, jack rabbit starts, full throttle operation ..all will give poor mileage...

Driving carefully will give gas mileage in the low to mid 60's

Driving like a nut will give mileage in the low 50's or less...

But in the scheme of things...5 or 10 MPG is meaningless....

Cookie

Quote from: Atesz792 on January 18, 2015, 07:48:28 AM
Anyone (esp. new riders) reading this later: MeeLee here does what many like to call "hypermiling".
You don't want to start experimenting with a GS you have just bought.
You don't want to lug a high-revving (for a twin at least) GS engine.
The stock gearing is just perfect for ~95% of GS riders, 6th already being an overdrive gear.
I'd advise anyone not to start messing with the stock gearing until they have ridden the bike at least 10k kilometres (~6k miles).

For someone interested in hypermiling, this is good information.
YMMV, peace :thumb:

Quote from: MeeLee on January 18, 2015, 05:54:47 AM

Another inheritent problem I've noticed, is that changing the gear ratio, somehow affects the air/fuel mixture.
The bike has no problems going WOT in 4th or even 5th gear, but 6th gear with the 17/35t, the engine load is different, and I have the impression that I need to get a bigger main jet. It is funny to note, that these problems are almost non-existent with the stock gears, or running 80+ mph at 7+k rpm.
They do appear when doing the same thing at 5k rpm.

Maybe I don't know enough about engines, but how is it possible the gearing of the bike affects the AFR? The AFR should be dependent only on the carbs, once the carbs give the engine the juice it needs the power from the combustion is send to the drive shaft and that's where the gear takes place.

Have you considered you over-geared down your bike and it's lugging as a result of extra strain placed on the clutch/gears/sprockets? I'd check this because AFR based on gears makes no sense and if this is the case you could be causing premature wear and warping to your bottom end.

Next question is, why try to get more mpg out of the bike anyway? The gs engine already leaves so much to be desired and is so underpowered - you can get some fun out of it dropping a few teeth on the sprocket, rejetting, cutting out the cat coverter + PAIR system, etc and still get 40+ mpg.

Stupid computer doubleposted. Mods delete this one thanks.

Nice to have some "comic relief" on the site.

Hope the newbees realize that is what MEELEE provides.

1- There's no such thing as lugging this engine above 3k RPM with these gearing. At the very worst perhaps when you're going past 85MPH; perhaps... We've had this conversation many times before. Lugging an engine like this at speeds between 35-80MPH is a Childs tale to scare the good people of thinking about efficiency.
I'm not going to argue this, I've had enough arguments about engine lugging, and enough miles on my past engines to prove it's a non issue. Sure you could lug your engine, but then you'll know when you do so. The engine will let you know (vibration).

Also, this is not considered hypermiling. Hypermiling includes using the clutch to 'roll' to a stop, with or without turning off the engine while doing so. I think 'eco-modding' will be a more correct term.

2- AFR is affected because the engine is under heavier load. That means valves stay open longer than under lighter load higher RPM, while at the same time. More air gets sucked in than fuel when the valves stay open longer (due to lower RPM), and the airfilter restricts less airflow at 5k rpm than it does at 8 or 9k rpm.
It does seem to affect the AF ratio.


And twocool, just because you don't agree with my way of riding, is no reason to call me 'insane'.
It's just not proper etiquette.
A lot of people are doing this to their bikes all over the world. There are still people out there who prefer 'just enough' power and good MPG, over 'plenty of acceleration, and high rpm'.
At the very least I would request the same politeness as anyone else gets in this forum; even if your views differ from mine!


And lastly,
People love to comment how 'impossible' and 'stupid' these mods are, but I find that many times people like me have tried it before, quite often a couple of years to a decade before, and where considered very knowledgeable, and their words where honored. Whatever I bring up here is not new knowledge! It's been proven and tried by many who now have several tens to 100's of K miles on their bikes.
I'm sure even in this forum there are a bunch of people who tried it before and are very content with it!


I never told anyone to do my mods, I just shared my findings in this thread (and opinions about 15/36t probably being better than 15/35t). That's all... No reason to get on the attack horse because your riding style differs from mine.

Quote from: MeeLee on January 18, 2015, 05:11:02 PM
2- AFR is affected because the engine is under heavier load. That means valves stay open longer than under lighter load higher RPM, while at the same time. More air gets sucked in than fuel when the valves stay open longer (due to lower RPM), and the airfilter restricts less airflow at 5k rpm than it does at 8 or 9k rpm.
It does seem to affect the AF ratio.

And lastly,
People love to comment how 'impossible' and 'stupid' these mods are, but I find that many times people like me have tried it before, quite often a couple of years to a decade before, and where considered very knowledgeable, and their words where honored. Whatever I bring up here is not new knowledge! It's been proven and tried by many who now have several tens to 100's of K miles on their bikes.
I'm sure even in this forum there are a bunch of people who tried it before and are very content with it!


I never told anyone to do my mods, I just shared my findings in this thread (and opinions about 15/36t probably being better than 15/35t). That's all... No reason to get on the attack horse because your riding style differs from mine.

I was under the impression AFR is independent of RPM and is determined by throttle position because the throttle controls the position of the butterfly valve which varies the vacuum and thus, the fuel and air being pulled in. Since you geared down your engine, the engine won't be able to draw in as much air and fuel (both I would guess, not just one) and you'd be getting chugging around 3/4 to WOT like you said. I don't think you have a sweet spot at any RPM because the AFR should be determined by weather or not you're WOT. It probably gets better as the engine picks up only because the engine is finally able to overcome the gear down. It's like when you swap a geared down V8 big block into a rock crawler. You'll destroy your engine trying to push it past 70.

If this is the case then a bigger main jet like you suggested would likely stop it from leaning out so much at 3/4 to WOT. I'd be concerned that if the engine is struggling at WOT you could warp your piston rods or something.

Addressing the last part, we're just questioning the futility of this effort. Why not buy one of those $500 chinese scooters that can go 60mph and get 100mpg if you want insane fuel economy?

Quote from: Dr.McNinja on January 18, 2015, 05:37:31 PM

Quote from: MeeLee on January 18, 2015, 05:11:02 PM
2- AFR is affected because the engine is under heavier load. That means valves stay open longer than under lighter load higher RPM, while at the same time. More air gets sucked in than fuel when the valves stay open longer (due to lower RPM), and the airfilter restricts less airflow at 5k rpm than it does at 8 or 9k rpm.
It does seem to affect the AF ratio.

And lastly,
People love to comment how 'impossible' and 'stupid' these mods are, but I find that many times people like me have tried it before, quite often a couple of years to a decade before, and where considered very knowledgeable, and their words where honored. Whatever I bring up here is not new knowledge! It's been proven and tried by many who now have several tens to 100's of K miles on their bikes.
I'm sure even in this forum there are a bunch of people who tried it before and are very content with it!


I never told anyone to do my mods, I just shared my findings in this thread (and opinions about 15/36t probably being better than 15/35t). That's all... No reason to get on the attack horse because your riding style differs from mine.

I was under the impression AFR is independent of RPM and is determined by throttle position because the throttle controls the position of the butterfly valve which varies the vacuum and thus, the fuel and air being pulled in. Since you geared down your engine, the engine won't be able to draw in as much air and fuel (both I would guess, not just one) and you'd be getting chugging around 3/4 to WOT like you said. I don't think you have a sweet spot at any RPM because the AFR should be determined by weather or not you're WOT. It probably gets better as the engine picks up only because the engine is finally able to overcome the gear down. It's like when you swap a geared down V8 big block into a rock crawler. You'll destroy your engine trying to push it past 70.

If this is the case then a bigger main jet like you suggested would likely stop it from leaning out so much at 3/4 to WOT. I'd be concerned that if the engine is struggling at WOT you could warp your piston rods or something.

Addressing the last part, we're just questioning the futility of this effort. Why not buy one of those $500 chinese scooters that can go 60mph and get 100mpg if you want insane fuel economy?

About the Chinese scooters/motorcycles: Been there, done that.
About warping anything in the engine: At low RPM there's less force on the bearings or anything else than at high RPM. See HP curve, engine at 2k lower RPM makes also lower HP.

About A/F ratio, like I said, the stock airfilter limits high air volume. Like it's not good enough to let all the air pass near to resistance free at high RPM.
That's why a lot of people equip it with K&N airfilters, or the lunchbox airfilter.
In essence, the bike at 90MPH sucks in less air at 5k RPM than at 8000 RPM. The higher air suction gets more restricted at 8K RPM with the stock filter (not so with a free-flow air filter); thus the bike gets a richer mixture at high RPM with the stock filter than with a free flow filter; or than when riding WOT at 2/3rd the RPM.

Since there's less vacuum resistance at the filter at lower RPM doing exactly the same performance as a stock gearing does at higher RPM, the bike will be running leaner (less fuel, more air).

So, yes, it does affect AFR.

Meelee, I'm really trying to understand your line of thinking on all this. Really. I'm not into reposting huge quotes on my phone, so I'll just copy and paste snipped sections. First off, what is the reasoning for increased chain sprocket wear mentioned here:

"The only problem I'm facing, is that with a 108 link chain, the rear sprocket will wear out the chain (or reverse). Sprocket/chain ratio couldn't be worse.
With the stock 110 link chain, the rear wheel chain adjustment will be close to the end, but it'll still be ok! Also chain-link/sprocket wear is quite good!"

Another thing that caught my eye is the AFR discussion. If you're essentially lugging your engine in 6th gear, a main jet change will help VERY little with that. And I'm failing to see the true relationship between gearing changes and AFR - Wot is wot regardless of how many teeth are on your rear sprocket.

The chain and sprocket wear depend on how many rotations the sprocket needs before the same tooth goes into exactly the same link. Optimally, with an even linked chain, you'd have an odd number of tooth. Let's say it was possible to have x-amount of links, on a 39T rear sprocket, the sprocket will need 39 rotations before the tooth hits the same chain link again (at best).

At worst (for ease of calculation), each tooth of the sprocket will hit the same link every rotation.

If you go to the bottom of gearing commander, you'll see it all calculated right there.

Define lugging the engine.
What does the engine do under load?
Just because the final gear is an overdrive, doesn't mean the engine will suffer shorter life.
Take a look at Citroën's 2cv. It had such an overdrive that the engine barely accelerated the car in 4th gear, and got 80MPG (for a car). Yet some of these cars got over 250.000km on them without an engine rebuild.

The difference of AFR lies in the amount of air intake that the engine gets.
The stock intake is restrictive. It creates more of a vacuum at high RPM than at low RPM.
That's the relation. It's like equipping a free flow air filter on the carburetor, you'll get similar amount of vacuum between air filter and carburetor with a free flow air filter at 8k RPM (as close to none) as using a restrictive air filter at lower RPM (close to none, but increased at high rpm).
That's where the correlation lies.

What a lot of people may be experiencing is perhaps the AF ratio being off, when going into tall gears, rather than lugging.

An engine that is taxed too high, will start knocking (piston motion is too much slowed down, that the spark fires at a too early stage; and is very similar to advancing your timing).
So instead of advancing your timing, you're slowing down the engine by increasing the load, and have the spark detonate at a better position; using taller gears it results in better efficiency and higher MPG.

A lot of people advance the timing. The shorter the gears (the smaller the counter sprocket, and larger the rear sprocket), the more the timing advance can be, and similar the taller the gearing, the more tardy the mechanical motion becomes and has a similar effect as advancing the timing.

There's no way you can destroy an engine due to too tall gears, unless you plan on going top speed with it, or going below an RPM that the engine is comfortable with pulling (2.75k rpm in my case, lower in lower gears).
There are limits of course, but my gear change is less than 20%, and is well within the acceptable range of modding most bikes.

if you wanted something to ride better at highway speeds, and got good MPG.. there's plenty of 800cc-1000cc bikes that are meant for that!  :thumb: :tongue2:

Hmmm.... not quite the answers I was hoping to get.

First, I do understand the sprocket / chain wear issue.

Second, I'm not understanding the logic of gearing changes and AFR. Regardless of what modifications have been done to the air intake (to an extent) / exhaust / sprockets / tire sizes / etc, CV carbs rely on the throttle position and vacuum from the engine to operate. So I'll repeat: wot is wot regardless of sprocket size. Now, if the gearing is so tall that the engine can't overcome wind resistance, you can hold the throttle wide open but never reach full vacuum.

Forget about what filter resists more flow at whatever rpm. If you aren't holding the throttle at wide open and the rpm's aren't close to matching, you aren't fully on the main jet. To put it another way - I'd like to see the dyno test results of running with stock gearing and your gearing for a comparison. If there is no change in horsepower and torque curves, than the air / fuel mixture is not affected.

MeeLee, there is no "free flow filter", I believe you mean lower pressure drop filter.

Any filter, by definition has a pressure drop.  A zero pressure drop filter is doing zero filtration.  If the filter area is increased, the pressure drop associated with the filtration can be markedly reduced, but never eliminated.  There is always a pressure drop across any filter that has air moving across it.  You are correct that decreasing this pressure drop is frequently favorable to efficiency...but...if you are running lean, it is likely due to the fact that the carbs are designed for X pressure drop, and you have reduced the pressure drop so that the new number is X-Y pressure drop.  I think you have not modified your carbs, correct?  Therefore, it stands to reason that your lean issue has nothing to do with sprockets and more to do with your filter modifications which have increased air flow while leaving fuel levels unchanged.

In my business I also do a great deal of engineering with pulleys (in relation to fan speeds and outputs), sprockets are using that same basic science that governs pulleys.

I am not an expert on motorcycles (yet!), but I know a great deal about pressures, flows, and the relationships between the various factors that determine flow.  I don't know enough about how the air intake is affected by throttle to say for sure, but it seems to me that higher RPM would induce more air than lower RPM....therefore, running a "long" sprocket combination to reduce rpm would make the air flow less (if anything), thus making the mix in the carb richer...

I do follow what you are saying with the sprocket changes you have made, and even if I don't fully understand why you are doing it, it is interesting.

Quote from: PantheraLeo on January 19, 2015, 07:38:03 AM
MeeLee, there is no "free flow filter", I believe you mean lower pressure drop filter.

Any filter, by definition has a pressure drop.  A zero pressure drop filter is doing zero filtration.  If the filter area is increased, the pressure drop associated with the filtration can be markedly reduced, but never eliminated.  There is always a pressure drop across any filter that has air moving across it.  You are correct that decreasing this pressure drop is frequently favorable to efficiency...but...if you are running lean, it is likely due to the fact that the carbs are designed for X pressure drop, and you have reduced the pressure drop so that the new number is X-Y pressure drop.  I think you have not modified your carbs, correct?  Therefore, it stands to reason that your lean issue has nothing to do with sprockets and more to do with your filter modifications which have increased air flow while leaving fuel levels unchanged.

In my business I also do a great deal of engineering with pulleys (in relation to fan speeds and outputs), sprockets are using that same basic science that governs pulleys.

I am not an expert on motorcycles (yet!), but I know a great deal about pressures, flows, and the relationships between the various factors that determine flow.  I don't know enough about how the air intake is affected by throttle to say for sure, but it seems to me that higher RPM would induce more air than lower RPM....therefore, running a "long" sprocket combination to reduce rpm would make the air flow less (if anything), thus making the mix in the carb richer...

I do follow what you are saying with the sprocket changes you have made, and even if I don't fully understand why you are doing it, it is interesting.

You pretty much understood what I tried to explain, and where more able to explain it than me, seeing your technical vocabulary in English is larger than mine.

There is one error in reasoning though;
At higher RPM, there is more airflow, thus also more air resistance with the stock filter.
More air resistance means more vacuum, thus more fuel from the jets goes in the mixture, and less air.
In other words, the mixture will run richer. With less airflow, there is less vacuum, thus less fuel in the piston, and more air, as it flows freer than fuel.
Lower RPM means running leaner for the same speed, as doing the same with high rpm.

You're right in the assumption that I haven't yet changed the main jet; it should still be pretty much stock, and it needs to be at least 5 sizes higher.

But thanks for the explanation; you're doing a better job than me in that field for sure  ;)

Holy cow!

in plain English:   "It just don't work that way!"


Cookie

Quote from: MeeLee on January 19, 2015, 06:52:21 PM

Quote from: PantheraLeo on January 19, 2015, 07:38:03 AM
MeeLee, there is no "free flow filter", I believe you mean lower pressure drop filter.

Any filter, by definition has a pressure drop.  A zero pressure drop filter is doing zero filtration.  If the filter area is increased, the pressure drop associated with the filtration can be markedly reduced, but never eliminated.  There is always a pressure drop across any filter that has air moving across it.  You are correct that decreasing this pressure drop is frequently favorable to efficiency...but...if you are running lean, it is likely due to the fact that the carbs are designed for X pressure drop, and you have reduced the pressure drop so that the new number is X-Y pressure drop.  I think you have not modified your carbs, correct?  Therefore, it stands to reason that your lean issue has nothing to do with sprockets and more to do with your filter modifications which have increased air flow while leaving fuel levels unchanged.

In my business I also do a great deal of engineering with pulleys (in relation to fan speeds and outputs), sprockets are using that same basic science that governs pulleys.

I am not an expert on motorcycles (yet!), but I know a great deal about pressures, flows, and the relationships between the various factors that determine flow.  I don't know enough about how the air intake is affected by throttle to say for sure, but it seems to me that higher RPM would induce more air than lower RPM....therefore, running a "long" sprocket combination to reduce rpm would make the air flow less (if anything), thus making the mix in the carb richer...

I do follow what you are saying with the sprocket changes you have made, and even if I don't fully understand why you are doing it, it is interesting.

You pretty much understood what I tried to explain, and where more able to explain it than me, seeing your technical vocabulary in English is larger than mine.

There is one error in reasoning though;
At higher RPM, there is more airflow, thus also more air resistance with the stock filter.
More air resistance means more vacuum, thus more fuel from the jets goes in the mixture, and less air.
In other words, the mixture will run richer. With less airflow, there is less vacuum, thus less fuel in the piston, and more air, as it flows freer than fuel.
Lower RPM means running leaner for the same speed, as doing the same with high rpm.

You're right in the assumption that I haven't yet changed the main jet; it should still be pretty much stock, and it needs to be at least 5 sizes higher.

But thanks for the explanation; you're doing a better job than me in that field for sure  ;)

Quote from: MeeLee on January 19, 2015, 06:52:21 PM
You pretty much understood what I tried to explain, and where more able to explain it than me, seeing your technical vocabulary in English is larger than mine.

There is one error in reasoning though;
At higher RPM, there is more airflow, thus also more air resistance with the stock filter.
More air resistance means more vacuum, thus more fuel from the jets goes in the mixture, and less air.
In other words, the mixture will run richer. With less airflow, there is less vacuum, thus less fuel in the piston, and more air, as it flows freer than fuel.
Lower RPM means running leaner for the same speed, as doing the same with high rpm.

You're right in the assumption that I haven't yet changed the main jet; it should still be pretty much stock, and it needs to be at least 5 sizes higher.

But thanks for the explanation; you're doing a better job than me in that field for sure  ;)

Fuel is drawn from the fuel bowl by the Venturi Effect, not vacuum.

(http://www.offgridworld.com/wp-content/uploads/2013/12/Venturi-effect.gif)

Quote from: twocool on January 19, 2015, 07:02:11 PM
Holy cow!

in plain English:   "It just don't work that way!"


Cookie

Quote from: MeeLee on January 19, 2015, 06:52:21 PM

Quote from: PantheraLeo on January 19, 2015, 07:38:03 AM
MeeLee, there is no "free flow filter", I believe you mean lower pressure drop filter.

Any filter, by definition has a pressure drop.  A zero pressure drop filter is doing zero filtration.  If the filter area is increased, the pressure drop associated with the filtration can be markedly reduced, but never eliminated.  There is always a pressure drop across any filter that has air moving across it.  You are correct that decreasing this pressure drop is frequently favorable to efficiency...but...if you are running lean, it is likely due to the fact that the carbs are designed for X pressure drop, and you have reduced the pressure drop so that the new number is X-Y pressure drop.  I think you have not modified your carbs, correct?  Therefore, it stands to reason that your lean issue has nothing to do with sprockets and more to do with your filter modifications which have increased air flow while leaving fuel levels unchanged.

In my business I also do a great deal of engineering with pulleys (in relation to fan speeds and outputs), sprockets are using that same basic science that governs pulleys.

I am not an expert on motorcycles (yet!), but I know a great deal about pressures, flows, and the relationships between the various factors that determine flow.  I don't know enough about how the air intake is affected by throttle to say for sure, but it seems to me that higher RPM would induce more air than lower RPM....therefore, running a "long" sprocket combination to reduce rpm would make the air flow less (if anything), thus making the mix in the carb richer...

I do follow what you are saying with the sprocket changes you have made, and even if I don't fully understand why you are doing it, it is interesting.

You pretty much understood what I tried to explain, and where more able to explain it than me, seeing your technical vocabulary in English is larger than mine.

There is one error in reasoning though;
At higher RPM, there is more airflow, thus also more air resistance with the stock filter.
More air resistance means more vacuum, thus more fuel from the jets goes in the mixture, and less air.
In other words, the mixture will run richer. With less airflow, there is less vacuum, thus less fuel in the piston, and more air, as it flows freer than fuel.
Lower RPM means running leaner for the same speed, as doing the same with high rpm.

You're right in the assumption that I haven't yet changed the main jet; it should still be pretty much stock, and it needs to be at least 5 sizes higher.

But thanks for the explanation; you're doing a better job than me in that field for sure  ;)

Which part?  I'm not trying to challenge what you say, I just want to understand better.  The fuel is fed by gravity, yes?  By decreasing the size of the line, the velocity is increased at the jet, yes?

I'm very confident that my filter pressure drop portion is correct, but I'm unsure of the correlation between air flow and rpm and throttle "demand".  How does it work, exactly?

Roaring via Tapatalk.

YES! YES! YES!.... :woohoo:

The manifold pressure is different animal than the venturi pressure in the carb....

Basically the carb works on air flow....more air flow=more air fuel mixture...the same ratio of air /fuel  but just more of it...

yeah, carbs are a bit more complicated than that due to the idle, midrange and high speed...different jets etc....

But basically the carb takes the air, and adds the correct amount of fuel..based on air flow(through the venturi)...not throttle setting or RPM...

BTW...The use of the word "vacuum" in engines bugs me....yes it is widely used, but technically incorrect.....

You have manifold PRESSURE...not vacuum....the manifold pressure is typically lower than ambient air pressure...but it is still pressure...it is not a negative value...it is a positive pressure..

Typically normal atmosphere is 29.92 in hg PRESSURE....

A running  engine might have say, 25 in hg manifold pressure...this is a pressure, just less pressure than ambient...

The pistons do not "suck" the air in....the air is PUSHED in by atmospheric pressure....

In a turbo or supercharged engine, the air is further pushed in by the turbo or supercharger, and manifold pressures are typically HIGHER than ambient...but even in this case the fuel air ratio remains basically the same...just a LOT more of it going into the cylinders....so more power!

Essentially, manifold pressure is an indication of "power"...so 25 in hg manifold pressure would indicate more power than 22 in hg...


BUT.....high manifold pressure and low RPM is really hard on an engine..

There is a lot of reading available on the internet...wiki manifold pressure (vacuum)...also wiki the difference between manifold pressure(vacuum) and venturi pressure (vacuum)

Cookie










Fuel is drawn from the fuel bowl by the Venturi Effect, not vacuum.

(http://www.offgridworld.com/wp-content/uploads/2013/12/Venturi-effect.gif)
[/quote]

Fuel is not fed to the engine by gravity....in the GS500 fuel is fed to the carb float bowl by gravity...

Think of the float bowl as just a tiny little fuel tank....

Air flows through the carburettor throat....it passes through the VENTURI, the venturi is a narrowed section of the throat....since it is narrow...the air flow speeds up to get through...

Bernoulli principal says total pressure remains the same....so ...when the air speeds up, the DYNAMIC pressure is increased, but since total pressure must remain the same, the STATIC pressure decreases.....so fuel is "pushed" through the jet...Higher pressure outside the jet...lower pressure in the venturi ...

If more air goes through the venturi...then more pressure difference...so more fuel goes through the jet...

The throttle is what you might consider a "restrictor"...it holds back the airflow...so less airflow...less fuel....less power...

Some examples:

lets say you are going DOWN a step hill.....what are you going to do with the throttle?

Most likely you're gonna CLOSE the throttle.....so the airflow is restricted....so the manifold pressure is low....the flow through the carb venturi is also low, because it is restricted by the throttle closed......so the engine is making very little power....but you don't need power, because you are going down hill....even though the RPM can be very high....you are making little power....low manifold pressure....throttle restricting air flow....


Now you get to the bottom of the hill, and go UP the next hill...what is the first thing you need to do?

OPEN the throttle....(maybe down shift too)...but when you open the throttle, you remove the restriction to the airflow in the carb....more airflow, more venturi effect, more gas....and HIGHER manifold pressure....more power is created...

YES, and air filter has a slight restriction to air flow...but this happens way before you get to the venturi...but this is why some guys want a low restriction air filter....less restriction in the air filter means more air flow through the carb is possible...more air means more gas means also higher manifold pressure means more power....

The trouble with free flowing filters is that they do not filter all that well...the performance increase is nearly imperceptible(on gs 500), while the potential damage to the engine is great....


Cookie












Which part?  I'm not trying to challenge what you say, I just want to understand better.  The fuel is fed by gravity, yes?  By decreasing the size of the line, the velocity is increased at the jet, yes?

I'm very confident that my filter pressure drop portion is correct, but I'm unsure of the correlation between air flow and rpm and throttle "demand".  How does it work, exactly?

Roaring via Tapatalk.
[/quote]

I agree with two cool, especially his point about manifold pressure. Atmospheric pressure is due to the 100 mile high column of air that is trying to crush everything at 14.7 PSI. That's many tons of force on the surface of your body.

Where I disagree is running an engine at higher loads will cause premature wear. Maintaining a given speed takes only a small percentage of the power capacity of an engine but contributes greatly to efficiency in MPG.

The point where you are "lugging" an engine is when adding throttle imput does not result in increasing speed. My GS pulls fine from 30 MPH in 6th, with stock gearing, but not from 25 MPH.

If your goal is to maintain speed then use 6th for maintaining speed, down to 25 MPH, BUT if you need to accelerate, THEN you must choose the appropriate gear for the rate of acceleration desired sometimes from 6th down to even 2nd in extreme cases.

If you do not choose the right gear and try to accelerate in a higher gear, then prolonged operation under those circumstances will cause increased wear and tear.

I am a hypermiler, but not so extreme that it impedes the flow of traffic or aggravates other driver-riders unless they are agressive tailgaters or such, then I just get away from them as they are stupid and will cause an accident that injures or kills me and then they, the casue of the accident, will drive away leaving me to bleed out and die.

regards
mech

Quote from: Old Mechanic on January 19, 2015, 08:23:14 PM
I agree with two cool, especially his point about manifold pressure. Atmospheric pressure is due to the 100 mile high column of air that is trying to crush everything at 14.7 PSI. That's many tons of force on the surface of your body.

Where I disagree is running an engine at higher loads will cause premature wear. Maintaining a given speed takes only a small percentage of the power capacity of an engine but contributes greatly to efficiency in MPG.

The point where you are "lugging" an engine is when adding throttle imput does not result in increasing speed. My GS pulls fine from 30 MPH in 6th, with stock gearing, but not from 25 MPH.

If your goal is to maintain speed then use 6th for maintaining speed, down to 25 MPH, BUT if you need to accelerate, THEN you must choose the appropriate gear for the rate of acceleration desired sometimes from 6th down to even 2nd in extreme cases.

If you do not choose the right gear and try to accelerate in a higher gear, then prolonged operation under those circumstances will cause increased wear and tear.

I am a hypermiler, but not so extreme that it impedes the flow of traffic or aggravates other driver-riders unless they are agressive tailgaters or such, then I just get away from them as they are stupid and will cause an accident that injures or kills me and then they, the casue of the accident, will drive away leaving me to bleed out and die.

regards
mech

Excessive load on the engine will cause premature wear. It's simple math. The harder you make your engine work to do anything, the more each part has to compensate for. If you maintain your RPMs engine load will remain effectively constant. Just because it's constant doesn't mean that it isn't causing damage. Especially if you're going 30 mph in a gear designed for 45-50 mph (overdrive). I'd imagine piston rings would be some of the first parts to go.

Running out to 6th gear on a motorcycle at 30 mph seems like a hazard. I'd imagine you have to go almost WOT to go anywhere. How are you not lugging the engine everywhere you go? How are you supposed to get out of being merged into if you have to pound down 4 gears to get any ponies to the rear wheel? On stock gearing I run my gears out and shift as late as possible and still get better fuel economy than anything but a geo. However, my bike will lug in 6th anywhere below 45mph and there is a significant drop in torque, which means I wont be able to react to hazards. Running richer with dynojet stage 3, pods, yoshi exhaust, and aggressive throttle I still average ~45 mpg. Whats the point?

I understand the challenge of hypermiling and how it could be fun, but it seems like a waste of time on something that is already incredibly efficient even raced out. With fuel so cheap, you're literally saving a few dollars here or there, which will go back into your bike because hypermiling is likely much harder on the oil/gears/drivetrain. Especially if you're following the whole turn your bike off at a stoplight thing, which will absolutely destroy the already fickle starter in the gs500. Even worse if you've rejetted the bike to be extremely lean, because all newer GSes have garbage oil coolers that do almost nothing for the overheating problem.

Lugging an engine....well at what point one is lugging is up for debate....

The case given of relative low speed in 6th gear...BUT at LOW throttle setting...is NOT lugging...

Trying to go up a hill, at low speed, in 6th gear, and using full throttle IS lugging....and does cause high loads on engine components, and can cause wear and damage...

overheating...detonation....low oil pressure are just a couple of problems.....con rods, rod bearings, pistons all are under high load....Ever try to drive an older carb car up a hill in too high a gear?  Hear the sound like marbles bouncing around in the engine?  That's lugging...and that's stress, and wear and potential damage...

Ever try to ride your ten sped bike up a steep hill in top gear?  Feel the strain in your muscles and knees?  That's lugging...Shift to low gear and you "spin" your way up with far less stress...

That being said...from the GS500 owners manual...

Shift Schedule:

Upshift schedule:

1-2....12 MPH
2-3....19 MPH
3-4....25 MPH
4-5....31 MPH
5-6....37 MPH

Downshift schedule:

6-5.... 25 MPH
5-4.... 19 MPH
4-3.... 12 MPH


While these numbers are certainly possible, and apparently do-able without damage...IF you drove like this, like a little old lady, you would be using about 5 HP of the 40 or so available...your mileage would be great!...the bike would fell like a wet noodle, and riding would be no fun at all...

The GS 500 has many gear ratios (6)... the engine is tolerant of wide RPM range...the gears are close and have wide overlap...all this makes for a very "drivable" bike...


Hypermiling on a GS500....

Really?  so what mileage do you regularly get?

If I ride conservatively...no WOT...smooth easy accelerations...steady long runs at 50 ~55 MPH....I get upper 60's to 70 MPG.....

If I drive in a more "fun" way...I get lower 60's


If I drive like a nut....I get upper 50's

No need to change gearing.....no need to drive like an old lady....no need to take some of the risks in hyper mileing...(drafting) turning engine off down hill etc..)

BTW...Mr. Lee is so full of misconceptions, and lack of understanding..and ignorant of basic physics, that it would take a book to correct all of them!



Cookie











mech
[/quote]

Excessive load on the engine will cause premature wear. It's simple math. The harder you make your engine work to do anything, the more each part has to compensate for. If you maintain your RPMs engine load will remain effectively constant. Just because it's constant doesn't mean that it isn't causing damage. Especially if you're going 30 mph in a gear designed for 45-50 mph (overdrive). I'd imagine piston rings would be some of the first parts to go.

Running out to 6th gear on a motorcycle at 30 mph seems like a hazard. I'd imagine you have to go almost WOT to go anywhere. How are you not lugging the engine everywhere you go? How are you supposed to get out of being merged into if you have to pound down 4 gears to get any ponies to the rear wheel? On stock gearing I run my gears out and shift as late as possible and still get better fuel economy than anything but a geo. However, my bike will lug in 6th anywhere below 45mph and there is a significant drop in torque, which means I wont be able to react to hazards. Running richer with dynojet stage 3, pods, yoshi exhaust, and aggressive throttle I still average ~45 mpg. Whats the point?

I understand the challenge of hypermiling and how it could be fun, but it seems like a waste of time on something that is already incredibly efficient even raced out. With fuel so cheap, you're literally saving a few dollars here or there, which will go back into your bike because hypermiling is likely much harder on the oil/gears/drivetrain. Especially if you're following the whole turn your bike off at a stoplight thing, which will absolutely destroy the already fickle starter in the gs500. Even worse if you've rejetted the bike to be extremely lean, because all newer GSes have garbage oil coolers that do almost nothing for the overheating problem.
[/quote]

So from a performance point of view, a 17/36t makes most sense.
The only problem I'm facing, is that with a 108 link chain, the rear sprocket will wear out the chain (or reverse). Sprocket/chain ratio couldn't be worse.
With the stock 110 link chain, the rear wheel chain adjustment will be close to the end, but it'll still be ok! Also chain-link/sprocket wear is quite good!

I can understand where you are coming from with this claim, its a take on the `hunting tooth` principle and you are absolutely correct

36 shares 7 factors with 108 and, only 1 with 110 so localised wear is (at least in theory) potentially going to be more of an issue with the 108 chain. However given the chain is subject to random shock loading, external contamination, varying manufacturing/material quality, possibly poor lubrication and alignment, is it going to be a significant issue  in the real world?......I think not.

http://everything2.com/title/hunting+tooth (http://everything2.com/title/hunting+tooth)

As for some of your other comments and beliefs.......particularly `lugging`I will leave that to the others  :D

The venturi effect still is subject to a change in intake pressure.
If you spray oil on your air filter, you'll be running richer, because there is an increase in air resistance by the filter, so the otherwise perfect AF ratio will be compromised, less air means richer.

Likewise, if you manage to get the engine running at 90MPH at 5k RPM, there's less air resistance at the filter, for the same workload as a bike doing 9k rpm.

The lower RPM bike will have a slightly more opened throttle than the bike going at 9k RPM.

So the 'vacuum' effect still affects the AF ratio, as the fuel supply towards the venturi is at atmospheric bar, while the airflow in the carburetor is at a different pressure.

Quote from: sledge on January 20, 2015, 08:40:44 AM
...
As for some of your other comments and beliefs.......particularly `lugging`I will leave that to the others  :D

I'm sure over time even those ideas will be understood ;)

My English is not perfect, and my technical vocabulary is even less... But at least with trying to understand some people are getting what I'm saying.. :)

Quote from: Old Mechanic on January 19, 2015, 08:23:14 PM
I agree with two cool, especially his point about manifold pressure. Atmospheric pressure is due to the 100 mile high column of air that is trying to crush everything at 14.7 PSI. That's many tons of force on the surface of your body.

Where I disagree is running an engine at higher loads will cause premature wear. Maintaining a given speed takes only a small percentage of the power capacity of an engine but contributes greatly to efficiency in MPG.

The point where you are "lugging" an engine is when adding throttle imput does not result in increasing speed. My GS pulls fine from 30 MPH in 6th, with stock gearing, but not from 25 MPH.

If your goal is to maintain speed then use 6th for maintaining speed, down to 25 MPH, BUT if you need to accelerate, THEN you must choose the appropriate gear for the rate of acceleration desired sometimes from 6th down to even 2nd in extreme cases.

If you do not choose the right gear and try to accelerate in a higher gear, then prolonged operation under those circumstances will cause increased wear and tear.

I am a hypermiler, but not so extreme that it impedes the flow of traffic or aggravates other driver-riders unless they are agressive tailgaters or such, then I just get away from them as they are stupid and will cause an accident that injures or kills me and then they, the casue of the accident, will drive away leaving me to bleed out and die.

regards
mech

+1 :thumb:
I agree!

6th gear with a 17/35 goes fine down to 2750 RPM or 35MPH.
When the engine is hot, it goes down to 2500RPM or 30MPH, but I usually shift to 5th gear there!

Quote from: twocool on January 20, 2015, 05:17:26 AM...
BTW...Mr. Lee is so full of misconceptions, and lack of understanding..and ignorant of basic physics, that it would take a book to correct all of them!



Cookie

Be careful of what you're saying, or your words will be used against you when the time comes!
you don't know me,
You don't know what I know or what I don't
You presume I don't know something, and presumption is dangerous.
Especially when you flavor your words like that!

I may not know everything in the world, but I write my findings, and my beliefs, based on much more complex principles, findings, logic and math, than what I believe you fathom I do.

At first you where 100% against what I said,
Now that some people understand some of the things I say, you start backing off, but still continue your attack on the things that are not aligned with how you perceive things to be!

You presumed a lot by making the statement you did above!

What if I where a mechanical engineer? Would that make you tone down a bit?
Lucky for you I am not. I do this for fun.
And I'm open to correction, but the above I hardly see as a correction.
I see it merely as making fun of someone, just because you don't agree...

I have much more to say, but it's enough.
Discuss the venturi issue a bit further here, perhaps you'd be able to understand the principles.
I don't get everything, but I do notice things, analyze them, and give my closest possible answer to the problem at hand. My bike is running leaner at 5k than at 8k rpm.

Mr. Lee...

What I , (and some others) are trying to figure out is exactly what you are trying to accomplish....

So far all I can figure is you want the GS500 to go really fast and get really good gas mileage at he same time...

You also, for some strange reason, want the engine to run really slowly?

Can you elaborate on what you intentions are...what are you trying to accomplish?

As far as your engine running lean at certain RPM and not lean at others....on what do you base this claim?   Have you examined the spark plugs?  Do you have and exhaust gas temperature gauge?  Have you done even one "scientific" experiment?

Are you smarter than the engineers at Suzuki?


Cookie

Quote from: MeeLee on January 20, 2015, 06:56:26 PM

Quote from: twocool on January 20, 2015, 05:17:26 AM...
BTW...Mr. Lee is so full of misconceptions, and lack of understanding..and ignorant of basic physics, that it would take a book to correct all of them!



Cookie

Be careful of what you're saying, or your words will be used against you when the time comes!
you don't know me,
You don't know what I know or what I don't
You presume I don't know something, and presumption is dangerous.
Especially when you flavor your words like that!

I may not know everything in the world, but I write my findings, and my beliefs, based on much more complex principles, findings, logic and math, than what I believe you fathom I do.

At first you where 100% against what I said,
Now that some people understand some of the things I say, you start backing off, but still continue your attack on the things that are not aligned with how you perceive things to be!

You presumed a lot by making the statement you did above!

What if I where a mechanical engineer? Would that make you tone down a bit?
Lucky for you I am not. I do this for fun.
And I'm open to correction, but the above I hardly see as a correction.
I see it merely as making fun of someone, just because you don't agree...

I have much more to say, but it's enough.
Discuss the venturi issue a bit further here, perhaps you'd be able to understand the principles.
I don't get everything, but I do notice things, analyze them, and give my closest possible answer to the problem at hand. My bike is running leaner at 5k than at 8k rpm.

Quote from: MeeLee on January 20, 2015, 06:56:26 PM
I don't get everything, but I do notice things, analyze them, and give my closest possible answer to the problem at hand. My bike is running leaner at 5k than at 8k rpm.

How are you sure? If you're positive this is happening I bet you're fuel starving your bike by hypermiling. The GSes are notorious for fuel starvation issues and are jetted really, really lean stock.

Mr. Lee...

I just re read your original post on this thread...and the many replies for those other than me...

I am not the only one poking fun at you....I am also not the only one who disagrees with your so-called "findings"

So I again state that you are a nut job!


Good Luck and have fun..


Cookie

Quote from: MeeLee on January 20, 2015, 06:20:05 PM
[...]
Likewise, if you manage to get the engine running at 90MPH at 5k RPM, there's less air resistance at the filter, for the same workload as a bike doing 9k rpm.
The lower RPM bike will have a slightly more opened throttle than the bike going at 9k RPM.
So the 'vacuum' effect still affects the AF ratio, as the fuel supply towards the venturi is at atmospheric bar, while the airflow in the carburetor is at a different pressure.

OK, I've had enough of this. Filter resistance / pressure drop is relative, and it couldn't give a damn about RPM or anything else you're trying to 'explain' here.
Let me introduce you to the Hagen-Poiseuille law:
R =(L*η*8 )/(r^4*π) where R is resistance, L is the length of the 'tube' (we're modeling things simplified for now), 'η' stands for viscosity (law is originally for fluids), 'r' is for radius (that tube again...), and I really hope you're already familiar with π (pi).
Resistance of a given tube is dependent on these alone. In any system, this requires correction, since the cross-section is ~never a perfect circle, but RPM or velocity for that matter do not alter resistance.

Quote from: twocool on January 20, 2015, 09:12:41 PM
Mr. Lee...

I just re read you original post on this thread...and the many replies for those other than me...

I am not the only one poking fun at you....I am also not the only one who disagrees with your so-called "findings"

So I again state that you are a nut job!


Good Luck and have fun..


Cookie

That's just too funny :icon_lol:

I "hypermile" my car more than the bikes, but I just consider it efficient driving and riding (the jerk that named it "hypermiling" coined that term much later than my efforts began). My $650 (with 3300 miles) 04 GZ250 averages right at 80 MPG but not ridden like a "grandmother". If you want to blow past the speed limits, I'll do my best to not impede your effort shouldwe ever share a road.

Actaully the most efficient acceleration is at 80% of full throttle in feedback fuel injected cars (like the 23 year old Sentra), with full load enrichment, you want to avoid. My Sentra, bought for $300 has averaged 37 MPG for 6 months since purchase with best highway tanks over 41 MPG with 182,000+ miles. The wife drives a 2012 Sorento she bought new and paid cash for.

The GS 500 averages mid 60s, sounds about the same as yours, two cool, when ridden about the same way as you posted for the same mileage. The Sentra is currently rated at 33 highway and 28 combined, so I'm 40% over EPA combined, costing me about 5.6 cents a mile for fuel only. Insurance is $250 a year for me. The bike is 2.3 cents a mile.

I considered gas cheap when it was 18 cents a gallon, when my fuel cost was less than a penny a mile in a 59 Corvette that would do 140 in 3rd and get 21 MPG average per tank.

Bought an 84 CRX 1.5 brand new that averaged 44 MPg for 50k when a lot of cars would not do 1/3 of that MPG. Never got run over or squished by a jacked up truck with 0-60 in 10 seconds and I have driven mid 50s VWs with a lot less power than the CRX.

I learned in 1974 on a Kawasaki 900 what happens when you have a vehicle that is soo fast people don't realize where you CAN be. Got tired of cages merging into me even when they apologised and I realized from their perspective I should not be where I was. I learned to expect stupid and relish the times when I was wrong.

If I was that paranoid about gas mileage, my 1965 Honda 50 (super cub) does 170MPG, 128 MPG is one ounce per mile and it tops out at 43 MPH, tagged as a scooter, no insurance required, bought for $250, running the next day after 21 years sitting. It will barely climb my 12 foot in 80 grade climb to get to the top of my driveway, too steep for the 78 Schwinn Varsity I bought for $10.

I guess I could get better mileage driving slower, but with 30 traffic lights in a 20 mile drive, that typically takes me about 31minutes, if you go faster or slower you just catch more lights and take longer to get there.

If you think efficient driving or riding is foolish then consider this. A big honking 4x4 at 10 MPG, will use $20,000 at @ $2 a gallon, $30k at $3 in 100k miles. The Sentra would use a little over $5k in fuel (same100k). Having driven economically for the past 35 years and several hundred k miles, the money saved paid for my house, and my working wife paid the bills while I built all $310k of the house for half price.

regards
mech

That was interesting reading...well thought out...

I've always owned "economy" cars....(well I did have a beat up Ford F 250...but that was used only on rare occasions for trailing)


Hypermileing is an interesting concept....my dad did it before it had a name...50 years ago...

My concept is to buy a vehicle which is efficient in the first place (smaller car...scooter, motorcycle)...then enjoy the savings on fuel....but just drive "normally"...

My weekend commute is 320 miles.....My car gets 32 MPG (or better)..but the GS500 doubles that..costs 1/2....and is a lot more fun...win-win...

But it is easy to be fooled....motorcycles cost more to own and maintain than cars...and you still need to have a car too.....(Now double registration costs..increased insurance costs..etc)  ..so the actual savings of the motorcycle are quite small...compared to owning just a car...but it's fun....


I don't thing the GS500 really lends itself to hypermileing....I mean you can get 60+ something MPH without really trying....What is the full potential?   70 MPG?...probably not even that much over the course of riding in various conditions...As you said...in cars...improvements of 40% are realistic...but for GS500 I'd say you'd be hard pressed to improve gas mileage more that 5%....So I just ride the way I feel like riding...and am happy with 60+MPG...

Changing sprockets, chains, filters, plugs, exhaust isn't really going to amount to much...and you have to add in the cost of those modifications...It would be a long time before reaching the break even point..

BTW...when it comes to hypermileing...I think I've got all your vehicles beat!   On weekends I fly Gliders (Sailplanes)......I've flown over 400 miles on a single flight...I've flown over 8 hours on a single flight...and I've gone over 150 mph....and use NO gas at all...(since there is no engine)


Cookie



         

Quote from: Old Mechanic on January 22, 2015, 12:55:13 PM
I "hypermile" my car more than the bikes, but I just consider it efficient driving and riding (the jerk that named it "hypermiling" coined that term much later than my efforts began). My $650 (with 3300 miles) 04 GZ250 averages right at 80 MPG but not ridden like a "grandmother". If you want to blow past the speed limits, I'll do my best to not impede your effort shouldwe ever share a road.

Actaully the most efficient acceleration is at 80% of full throttle in feedback fuel injected cars (like the 23 year old Sentra), with full load enrichment, you want to avoid. My Sentra, bought for $300 has averaged 37 MPG for 6 months since purchase with best highway tanks over 41 MPG with 182,000+ miles. The wife drives a 2012 Sorento she bought new and paid cash for.

The GS 500 averages mid 60s, sounds about the same as yours, two cool, when ridden about the same way as you posted for the same mileage. The Sentra is currently rated at 33 highway and 28 combined, so I'm 40% over EPA combined, costing me about 5.6 cents a mile for fuel only. Insurance is $250 a year for me. The bike is 2.3 cents a mile.

I considered gas cheap when it was 18 cents a gallon, when my fuel cost was less than a penny a mile in a 59 Corvette that would do 140 in 3rd and get 21 MPG average per tank.

Bought an 84 CRX 1.5 brand new that averaged 44 MPg for 50k when a lot of cars would not do 1/3 of that MPG. Never got run over or squished by a jacked up truck with 0-60 in 10 seconds and I have driven mid 50s VWs with a lot less power than the CRX.

I learned in 1974 on a Kawasaki 900 what happens when you have a vehicle that is soo fast people don't realize where you CAN be. Got tired of cages merging into me even when they apologised and I realized from their perspective I should not be where I was. I learned to expect stupid and relish the times when I was wrong.

If I was that paranoid about gas mileage, my 1965 Honda 50 (super cub) does 170MPG, 128 MPG is one ounce per mile and it tops out at 43 MPH, tagged as a scooter, no insurance required, bought for $250, running the next day after 21 years sitting. It will barely climb my 12 foot in 80 grade climb to get to the top of my driveway, too steep for the 78 Schwinn Varsity I bought for $10.

I guess I could get better mileage driving slower, but with 30 traffic lights in a 20 mile drive, that typically takes me about 31minutes, if you go faster or slower you just catch more lights and take longer to get there.

If you think efficient driving or riding is foolish then consider this. A big honking 4x4 at 10 MPG, will use $20,000 at @ $2 a gallon, $30k at $3 in 100k miles. The Sentra would use a little over $5k in fuel (same100k). Having driven economically for the past 35 years and several hundred k miles, the money saved paid for my house, and my working wife paid the bills while I built all $310k of the house for half price.

regards
mech

Thanks tc. A glider is one of the few things stil on my bucket list, would love to ride the updrafts and thermals on the windward side of the rockies.

regards
mech

Hang on twocool! ... point of order! .. your glider doesn't use fuel but the tow plane or possibly the donkey engine on the ground cable does!? ... carbon footprint right there! Nyah Nyah! :thumb:

Quote from: Old Mechanic on January 22, 2015, 12:55:13 PM
I "hypermile" my car more than the bikes, but I just consider it efficient driving and riding (the jerk that named it "hypermiling" coined that term much later than my efforts began). My $650 (with 3300 miles) 04 GZ250 averages right at 80 MPG but not ridden like a "grandmother". If you want to blow past the speed limits, I'll do my best to not impede your effort shouldwe ever share a road.

Actaully the most efficient acceleration is at 80% of full throttle in feedback fuel injected cars (like the 23 year old Sentra), with full load enrichment, you want to avoid. My Sentra, bought for $300 has averaged 37 MPG for 6 months since purchase with best highway tanks over 41 MPG with 182,000+ miles. The wife drives a 2012 Sorento she bought new and paid cash for.

The GS 500 averages mid 60s, sounds about the same as yours, two cool, when ridden about the same way as you posted for the same mileage. The Sentra is currently rated at 33 highway and 28 combined, so I'm 40% over EPA combined, costing me about 5.6 cents a mile for fuel only. Insurance is $250 a year for me. The bike is 2.3 cents a mile.

I considered gas cheap when it was 18 cents a gallon, when my fuel cost was less than a penny a mile in a 59 Corvette that would do 140 in 3rd and get 21 MPG average per tank.

Bought an 84 CRX 1.5 brand new that averaged 44 MPg for 50k when a lot of cars would not do 1/3 of that MPG. Never got run over or squished by a jacked up truck with 0-60 in 10 seconds and I have driven mid 50s VWs with a lot less power than the CRX.

I learned in 1974 on a Kawasaki 900 what happens when you have a vehicle that is soo fast people don't realize where you CAN be. Got tired of cages merging into me even when they apologised and I realized from their perspective I should not be where I was. I learned to expect stupid and relish the times when I was wrong.

If I was that paranoid about gas mileage, my 1965 Honda 50 (super cub) does 170MPG, 128 MPG is one ounce per mile and it tops out at 43 MPH, tagged as a scooter, no insurance required, bought for $250, running the next day after 21 years sitting. It will barely climb my 12 foot in 80 grade climb to get to the top of my driveway, too steep for the 78 Schwinn Varsity I bought for $10.

I guess I could get better mileage driving slower, but with 30 traffic lights in a 20 mile drive, that typically takes me about 31minutes, if you go faster or slower you just catch more lights and take longer to get there.

If you think efficient driving or riding is foolish then consider this. A big honking 4x4 at 10 MPG, will use $20,000 at @ $2 a gallon, $30k at $3 in 100k miles. The Sentra would use a little over $5k in fuel (same100k). Having driven economically for the past 35 years and several hundred k miles, the money saved paid for my house, and my working wife paid the bills while I built all $310k of the house for half price.

regards
mech

I see your point. I just am part of the school of that that says if you can't afford the gas, don't buy the vehicle. There's no point in detuning your supra/MR2/ferrari/whatever to get extra gas miles. Ruins the car and all the fun that comes with it. Same goes for literally any bike. Buy a geo/scooter if you want to save gas and have a weekend romper that gets 10mpg but runs a quarter mile in 10 seconds. I consider cars an investment in fun, and less as a way to get back and forth somewhere.

LOL...Yeah....I was waiting for that....but that's less than a gallon....(for a tow plane launch)...winch launch is ounces...(or electric)  ...it is possible and done many times to use human launching of a sailplane...they pull back on bungee cords....a couple places in the world, they just let' em roll down a steep hill and over the edge...

Then of course there are hang gliders...mostly foot launched..

Please don't tell me that you believe that carbon is a pollutant?


Cookie

Quote from: Janx101 on January 22, 2015, 08:47:23 PM
Hang on twocool! ... point of order! .. your glider doesn't use fuel but the tow plane or possibly the donkey engine on the ground cable does!? ... carbon footprint right there! Nyah Nyah! :thumb:

I initially bought the GS, after careful consideration between a $2100 2004 GS with 11k miles on, or a fairly new Ninja 300 for double that.

Doing the math, I needed a 400cc, and the only thing close was a Yamaha SR400; but I wasn't willing to pay the $8k + dealerfees and taxes new price. The Ninja goes just as fast as this GS does, however at a screaming 11-13k RPM.
So I went with a larger sized engine, the GS has a <500cc one.

The performance is good enough to do 100MPH comfy. I'm just trying to maximize MPG and MPH, and in the process save the engine from wear (all ye lugger believers, I'm not of the same opinion).

I bought the GS because my Rebel250 was no longer keeping up on the interstates (often riding WOT for hours on end, which depends on the wind, and seating position is 75MPH-85MPH, and it tops out at 93MPH in ducked position with legs on passenger pegs.
The little Rebel does 85MPG after modification, and 66MPG on the highway at WOT.

The GS does about the same top speed (I still need to rejet), and does ~45MPG on average over 3 tanks, on constant speeds over 80MPH.
I haven't yet tested 35-45MPH roads.

My Chevrolet Cruze eco gets 60MPG avg. at 50MPH. And 50MPG avg at 60MPH.
The total average is closer to 36.5MPG, 36.8 with BP Premium fuel.  This is light highway riding at 60MPH, a few miles at 35-40MPH, and few stop lights.
It's not bad at all, considering the Chevy only got port fuel injection, not direct injection; and it got 148HP, which is about 10-40HP more than most eco cars out there!
Combined with it's 3200 curb weight, it does accelerate nicely (although I wished I could have the Sonic with the 1,4L Ecotec engine, instead of the 1.8L NA.

Increasing your gas mileage by 10% over 100k miles (the avg life of the car), results in saving $3-4k!
For a motorcycle, it results in ~$1000 on 50-75k miles, well worth the investment of sprockets, and decrease of oil changes (oil stays well longer at lower RPM and temperatures).

There are lots of people who can afford the gas, but take pleasure in saving a buck or two per tank; resulting in quite the savings in the end.

One of the reasons I have motorcycles, is not only the fun factor, but also I don't use my car, see places, and thus have less wear, repairs, gas usage, and maintenance on my vehicle.
The $3k investment is well worth it. Not if I get in an accident, but I'd gladly trade the fun factor with the increased risk of an accident, than sit in a boring car safely...

Not to mention, women get horny sitting on that vibrating seat!

Nahh twocool. .. ain't no tree huggers in my house! ... I acknowledge the existence of 'carbon footprint' as a measuring tool only. .. carbon is great stuff! ... makes tyres black, good on the hibachi cooking!, scientists run some sort of dating service with it! .. 'geeks <3 carbon' possibly?, good for emergency notes on trees if you lost in the.forest without a pencil!, add an A and great pasta sauce! ... life on the planet would be really weird without carbon! :thumb:

Instant double post! ...

Umm MeeLee. .. you change your oil at 6000km/4500 miles in the gs500 or suffer the consequences! Lol

... and 'women get horny on the vibrating seat' ?!? ... possibly. ... but not necessarily! ... so are you saying every woman rider is constantly horny?! Hmmmm? .... lol

Mr. Lee says,

"Increasing your gas mileage by 10% over 100k miles (the avg life of the car), results in saving $3-4k!
For a motorcycle, it results in ~$1000 on 50-75k miles, well worth the investment of sprockets, and decrease of oil changes (oil stays well longer at lower RPM and temperatures)."

Math check!   

say 60,000 miles @ 60 MPG = 1000 gallons of gas...

at $2 a gallon that's $2000

Now if you increase your mileage by 10%...(which is VERY unlikely on a gs500, but let's use your 10% for sake of argument.....)

So...60,000 miles @ 66 MPG =909 gallons....

You saved 91 gallons.....@$2 a gallon that is $182 in savings over the life of the bike...(it takes most people 10 years or so to put on 60,000 miles)...


You did not save $1000....you saved $182...but wait!   New chain $100...new sprockets...$60....your  time and effort is worth a few bucks...so at best you break even...

But wait, there's more....realistically, mods to the GS 500 are going to give less that 5% fuel economy increase...so now you saved $90...minus the cost of the mods you you're a hundered or so in the hole...

But wait there's more....Mr. Lee...you are managing to get 20% LESS fuel economy than a stock GS500 with an average rider!!!...

60,000 miles @ 48 MPG = 1250 gallons of fuel...

At $2 a gallon that's $2500....

So you're behind $500 plus the couple hundred for the mods...


Hmmmmm....????


Just sayin'...


Cookie

Mr. Lee says, "Doing the math, I needed a 400cc, and the only thing close was a Yamaha SR400; but I wasn't willing to pay the $8k + dealerfees and taxes new price. "


Well the SR400 has a MSRP of $6000...not $8000.....my local Yamaha dealer has them on sale for $5200.....interesting motorcycle...most experts consider them overpriced... for what you get....

It is not even in the same league with the GS500 IMHO....and for the price... the GS 500 is superior in every way.  I use the GS500 as a daily and long distance commuter...the SR400 is more of a Sunday afternoon, mess-around-town or ride-in-the-country bike...  It is really a nostalgia throw back kind of deal..

BUT...I am seriously considering getting an SR400....not to replace my gs500 ...but to use as a project to build a cafe racer....not to save money...not to save gas...rather, just for the fun of it...lots of aftermarket modification parts for the SR400...


Cookie

Mr Lee says, "
I bought the GS because my Rebel250 was no longer keeping up on the interstates (often riding WOT for hours on end, which depends on the wind, and seating position is 75MPH-85MPH, and it tops out at 93MPH in ducked position with legs on passenger pegs.
The little Rebel does 85MPG after modification, and 66MPG on the highway at WOT.

The GS does about the same top speed (I still need to rejet), and does ~45MPG on average over 3 tanks, on constant speeds over 80MPH.
I haven't yet tested 35-45MPH roads."


No way that a Rebel goes as fast as a GS500!


Cookie

Mr. Lee....

Your logic, which brought you to the GS500, makes perfect sense to me.  I too went from a Honda Rebel to the GS500....and basically with the same reasoning you had....

What I don't understand is why you seem so dissatisfied with the bike?   

I absolutely love it!

I've put on 48,000 miles since new....no complaints...there is nothing I would do differently!

OK..so I did put on some Suburban Machinery clubmans bars...just more comfortable for me...

Yeah and red LED's in the instruments....that's the extent of my mods!

LOL!

Cookie

I'm not dissatisfied with the bike.
It had a few kinks that could have been ironed out, like a tad more power in the low revs, to allow it to run more eco friendly.
The 500cc is really a 480 something cc, so it's not getting a real 110MPH peak, but 100MPH peak (the Honda CB500 bikes do 110+MPH).
Gas mileage so far has been 35-40MPG at 80-100MPH, it's a stretch getting 55+ MPG on this bike doing 45-50MPH (I'll have to do a valve adjustment, not done at 13k miles yet).

I had hoped to get at least 60MPG, and 65-70MPG with the mod, but I guess after the valve adjustment I can tell more.

So my disappointment is in it not going as fast as I had hoped, not getting as good gas mileage (most 650-750cc bikes get the same gas mileage), and the handlebars being way too low for a touring bike.

All valid claims.

Just because this is a 2004 bike, doesn't mean that these things can't be updated over time, and better parts are available.

Honda Rebel 250 with modded sprockets goes 92MPH top speed, ducked forward with a light wind in the back, 83MPH wind still top speed, and 80MPH sitting upright.

My GS does 112MPH indicated top speed wind in the back (-10% = 101mph real speed)
100MPH sitting upright (-10% = 91mph),

So the GS does 10MPH faster than the Rebel (or only 10% faster, for 33-50% worse MPG, and double the cc).

Quote from: Janx101 on January 23, 2015, 03:52:09 AM

... so are you saying every woman rider is constantly horny?! Hmmmm? .... lol

I'd like to believe that!
At least mine is! :D

Mr. Lee,


YOU desire:

a GS500 which goes 130 MPH

AND gets 85 MPG...


I desire:

World peace,

a tall blonde with big hooters,

and $1,000,000



Who is being more realistic?


Cookie

(http://dailyhaymaker.com/wp-content/uploads/2014/01/drevil.png)

$1m.......is that all?

:D

Quote from: MeeLee on January 23, 2015, 10:35:12 PMHonda Rebel 250 with modded sprockets goes 92MPH top speed

The real question here is, are you seeking professional help for your Crack Addiction? No 16.1 HP bike is going to get to 80 Mph let alone 92 Mph, regardless of the gearing, it doesn't have enough beans to pull it off  :cookoo:

HA HA HA



LMFAO!!!


I'm tryinng to be "realistic"...


Cookie

Quote from: sledge on January 24, 2015, 07:44:55 AM
(http://dailyhaymaker.com/wp-content/uploads/2014/01/drevil.png)

$1m.......is that all?

:D

Quote from: Suzuki Stevo on January 24, 2015, 07:54:31 AM

Quote from: MeeLee on January 23, 2015, 10:35:12 PMHonda Rebel 250 with modded sprockets goes 92MPH top speed

The real question here is, are you seeking professional help for your Crack Addiction? No 16.1 HP bike is going to get to 80 Mph let alone 92 Mph, regardless of the gearing, it doesn't have enough beans to pull it off  :cookoo:

Isn't the speedo driven off the front sprocket (unlike the speedo of the GS, driven off the front wheel) on the Rebel? So at least he could see an indicated 92? I'm starting to think he's delusional, too :icon_confused:

Really now....since we read this forum on the Internet...and you can search just about anything you want on the Internet...and You tube  shows anything you might ask for......

Why do people think they can Bullshit  :bs: on the Internet??

Here's the Honda Rebel 250...

https://www.youtube.com/watch?v=qxOmLc8M2P4


Cookie

Quote from: Atesz792 on January 24, 2015, 11:29:52 AMIsn't the speedo driven off the front sprocket (unlike the speedo of the GS, driven off the front wheel) on the Rebel? So at least he could see an indicated 92? I'm starting to think he's delusional, too :icon_confused:

I don't see a Rebel 250 holding even 80 Mph indicated unless downhilll, 70 indicated is probably closer the 65 Mph actual anyway, regardless of where it's driven from. 

http://en.wikipedia.org/wiki/Honda_CMX250C (http://en.wikipedia.org/wiki/Honda_CMX250C)

Top speed    70 mph (110 km/h)
Power    16.1 hp (12.0 kW)
Torque    12.4 lb·ft (16.8 N·m)

Induction Single 26mm diaphragm-type constant-velocity (CV) carburetor
Valve Train SOHC: two valves per cylinder

One carb and one cam, 92 Mph...yeah right  :icon_rolleyes:

Yep...you just can't beat the laws of physics....

I had my Rebel to an indicated 75 once on a long gradual down hill straight...

With speedometer error...lucky to be 70...

Cookie

Quote from: Suzuki Stevo on January 24, 2015, 12:21:19 PM

Quote from: Atesz792 on January 24, 2015, 11:29:52 AMIsn't the speedo driven off the front sprocket (unlike the speedo of the GS, driven off the front wheel) on the Rebel? So at least he could see an indicated 92? I'm starting to think he's delusional, too :icon_confused:

I don't see a Rebel 250 holding even 80 Mph indicated unless downhilll, 70 indicated is probably closer the 65 Mph actual anyway, regardless of where it's driven from. 

http://en.wikipedia.org/wiki/Honda_CMX250C (http://en.wikipedia.org/wiki/Honda_CMX250C)

Top speed    70 mph (110 km/h)
Power    16.1 hp (12.0 kW)
Torque    12.4 lb·ft (16.8 N·m)

Induction Single 26mm diaphragm-type constant-velocity (CV) carburetor
Valve Train SOHC: two valves per cylinder

One carb and one cam, 92 Mph...yeah right  :icon_rolleyes:

Over on the Honda Rebel forum....the consensus is that the Rebel speedo is 10% OVER...typical of most motorcycles...

So an indicated 75 is only 68 MPH....

The Rebel is a great bike....it does what it was designed to do...but it's not "fast"..

The GS 500 is also not what I would call "fast", but it will easily run circles around a Rebel....

Cookie

Quote from: Suzuki Stevo on January 24, 2015, 07:54:31 AM

Quote from: MeeLee on January 23, 2015, 10:35:12 PMHonda Rebel 250 with modded sprockets goes 92MPH top speed

The real question here is, are you seeking professional help for your Crack Addiction? No 16.1 HP bike is going to get to 80 Mph let alone 92 Mph, regardless of the gearing, it doesn't have enough beans to pull it off  :cookoo:

I've reached 92 on the interstate with my Rebel, ducked forward, feet on passenger pegs, small tail wind.
But like I said, it tops out at 85mph normally.

The Rebel, unlike the Suzuki, has a 1-2MPH difference with GPS at top speed, not 10MPH. You can pretty much say the Speedo is dead on.

And so sorry to disappoint you guys, but stock the Rebel does 83MPH. It takes a small sprocket adjustment to get it up to 85MPH. I do 85-87MPH on a regular base with it on the interstate.
I have a good 3-6k miles with it in city, and double that on the highways and interstate.

I told you it's engine was a lot better than the Suzuki, didn't I? (save for the cc difference, resulting in lower power).