A little while ago someone asked about a dyno run for a stock bike.
Being curious I had my completely stock 93 put on the Dyno.
Condition of the bike; 7000 miles, bone stock. I've had it about 3 months, the only thing I've done is to change the oil and the plugs.
I think the A/F ratio graph bears out a lot of comments made on the board.
The interuption at ~7600 RPM is caused by a balky ignition pickup on the dyno.
(http://home.interserv.com/~dbarile/dyno-01.jpg) (alt+p)
:o wow :o
40.28hp got to give the 487 props for that :thumb:
HEHE 29.71 ft/lbs just enough to tighten up bolts :lol: that's funny a GS500 powered tourque wrench.
Man, the max torque point comes from a little blip. That's a tiny blip, too. 40.28 RWHP, not bad at all! That air/fuel mix is CRAZY!!! Look at thing, bouncin around like nothing else.
I'ma get my '04 dynoed next week, hopefully.
any chance the carbs were synced? tryin to reason that "thing" of a mixture line
Thanks a lot dbarile!!! :cheers:
That is exactly what I was looking for... and what I expected somehow:
the "optimum slow" riding spot is around 4500 rpm. There the air mix is closest to the theoretical optimal ( 1 : 18 ).
Hence -this was my point in changing the sprocket to 17 teeth- by lowering the rpms on the cruising speed of 60 mph (yes, that's the kind of slow-po riding I do... :oops: ), the engine falls into the hoop of the curve between 4000 and 5000 rpm... for better mileage and engine efficiency...
How does this sound?
Cool thanks, I've been wanting to see one. Now if I'm not mistaken, for 1/4 action, shift at redline should suffice. At least is sure looks like that.
oh wait. the graph stops at 9500. NVM.
Well I wanted a stock run to compare to any later mods I do so I didn't touch a thing.
My thoughts are to adjust the valves, change the jets and rod and do it again.
I belive the crazy A/F ratio is tied to the jets and metering rod.
The next dyno run should tell.
Should have asked for another run that had contiguous data and ran all the way up to 11K.
This is actually one of three runs that were done. I'm not sure if there is just a printing problem or a software problem but I know it was taken up to redline for each run because I watched. The spike showed up in each run. Maybe a glistch in the pickup because I didn't notice the bike cough at all.
I was more interested in the trip to peak power and the A/F ratio than the area from 9500 to 11K. The power has already peaked and I don't plan on spending a lot of time at 11K. This gives me what I was really after which is a baseline for any mods. Your are right however that it would have been nice to see the full range.
I know that the cheapest method woud be to complete intake, carb and exhaust mods and then retest to get the jetting perfect. But I'm just curious enough to change the intake and jetting and retest.
not bad for a stocker ive seen as low as 33 hp and as high as 42hp on stock gs's .last time mine was dyno'ed made 66 ponies and wasnt even broke in yet
66hp...what all is done to it?
Quote from: AlphaFire X5Man, the max torque point comes from a little blip. That's a tiny blip, too. 40.28 RWHP, not bad at all! That air/fuel mix is CRAZY!!! Look at thing, bouncin around like nothing else.
I'ma get my '04 dynoed next week, hopefully.
Is that really rwhp or just the max hp?
porsche- the list is long 9mm over custum pistons,EXTENSIVE headwork,giant megacycle cams,dual plug head 4cyl.coils,39 CR specials carbs more &more bike will run with sv 650's all day long ,also reworked tzr 250 front end fox shock 4.5in gsxr wheel .i used to race clubman class in wera am thinking about putting it back on street ,just need to add lights and charging system
Alright, here's a question.
That bike is CRAZY rich from 5500 up and very lean from 3500 to 5500. The consensus on the board is to bump your main jets up a few sizes.
Why on earth would you increase the main jet size when it is already SO rich up top? This is driving me crazy, because if something is already THAT rich, why would you want it to be even richer? Opening up the idle screws should clear up the low end leanness, but the top end doesn't look like it needs to be increased.
Someone please explain this to me.
Quote from: onefastgs500porsche- the list is long 9mm over custum pistons,EXTENSIVE headwork,giant megacycle cams,dual plug head 4cyl.coils,39 CR specials carbs more &more bike will run with sv 650's all day long ,also reworked tzr 250 front end fox shock 4.5in gsxr wheel .i used to race clubman class in wera am thinking about putting it back on street ,just need to add lights and charging system
I would just like to get around 50-52 HP.
I wonder what kind of would that would involve?
Well this is a bone stock bike. I imagine that putting a freer flowing exhaust on it and/or a freer flowing air filter will move the whole range up or leaner. Then you probably would want bigger mains.
Looking at the jet chart/matrix that I've seen on the web, the reccomendations are for setting the stock main jets to 125 from about 122.5. Not much of a jump. But it would push the high end richer, how much who knows.
The guy who dyno'd the bike seemed to think that the high end mixture was too bouncy. He reccomended replacing the metering rods with a tapered set. He was really perplexed that I wanted to dyno a stock bike, but went about it with glee once I explained that it was a simple matter of curiousity.
I am seriously considering simpy rejetting the bike and putting it on the dyno again. I'm curious what it would look like.
There is another dyno place closer to home than this place. I will call them sometime this week and see what their prices are. I might even do another stock run just for fun and see how they compare
blazin,we did one gs with just the piston kit and rejet and got 51 ponies,but the pistons are expensive and require new sleeves and boring of cyl and cases.
What else are you gonna spend money on?
Dyno Runs?
Seriously, I would like to try some engine mods, but it will likely be next year.
I'm keeping my eye out for a cheap engine to change out pistons on.
Optimal jetting would air/fuel around 12.5 It's at that point for a split second of a rev, but it's rich aside from that one point. Putting in an air filter that is freer flowing should lean out the top end, thus making it operate in the optimal jetting range. I don't see why you'd bump the mains up on a STOCK bike when it's like that. A freer flowing exhaust (caused by the diameter of the headers, not the open can) would likewise need a jetting change if it pushed the ratio too far to the lean side of things. However, the drastic changes proposed in the jetting matrix perplex me.
Think about it. If a stock bike is THAT rich with 122.5, why would you go to a 147.5 or even a 145 main? I highly doubt that a simple exhaust and filter change could create such a drastic need for jetting.
On my '04 I changed the jetting to 137.5 mains while using a K&N filter. That's a bump of 3 sizes. I highly doubt that a K&N filter would cause such a dramatic change and need. I'm going to pull my carbs and put the jetting back to stock.
So the hp, and torque graphs are showing peak performance around 8k. But what is the air/fuel graph suppose to tell me.. seems like the ratio is bouncing all over.. is this a typical result graph? ive never see the air/fuel graph before. what info do i want from the ratio graph?
I don't recall anyone advocating 140 sized mains on a stock bike. The matrix I have says 125. 'Optimal mixture' may be open to SOME interpretation.
Before we have a 'discussion' about the jetting matrix, I going to clearly say I don't know if it is correct or not. I'm not defending it, but I am citing it as others here have done. My view is that it is a starting point and nothing more. It does seem to be correct on about the idle jets though. I have a set of 40's I haven't installed. It might be interesting to see the mixture after only the idle jets are are changed.
The guy who dyno'd my bike implied that he was more interested in stable mixture over the entire range. Obviously he wasn't talking about 15, but he seemed more intrested in obtaining a straight line 'near' the optimal. He didn't say that but that was my impression. Next time I see him I'll ask him straight out.
I think the one place I might take issue with is the exhaust. If your muffler is restrictive then changing it will certainly free up the engines breathing apart from the pipes.
As far as your bike goes, it might be interesting to see a dyno run on that as well. Where did you get the 137.5 from?
Quote from: bargovicSo the hp, and torque graphs are showing peak performance around 8k. But what is the air/fuel graph suppose to tell me.. seems like the ratio is bouncing all over.. is this a typical result graph? ive never see the air/fuel graph before. what info do i want from the ratio graph?
I understand that this is pretty typical for a stock GS500. I think the info you need is that the mixture needs to be richer at the low end and better controlled across the whole spectrum. Ideally you want the mixture at optimum across the whole range.
I've got an '04, so the carbs are different. I've got a mid main jet and a different pilot jet. The consensus, not only by the matrix but in the FAQ section about jetting here on the board, is still to increase the mains and mid mains more than a few number of sizes. There are some who even say that you need a 150 main on the old bikes... Honestly. A 150. That's absurd. Hell, a 140 is absurd. Mine is rich right now and it's a size down from that. My stock numbers are 130/60/17.5.
I bumped the main up 3 sizes, the mid-main up one size, and the pilot up one size, per the instructions in the FAQ and the jetting matrix.
My gas mileage is also crap-tastic now. I'm getting low 40s. I used to get mid 50s.
Quote from: AlphaFire X5I've got an '04, so the carbs are different. I've got a mid main jet and a different pilot jet.
Yea. I knew that your carb and mine were different. I'm only looking at the matrix for my carbs. And I think I agree that a 140 or 150 jet would be too much.
Quote from: AlphaFire X5
My gas mileage is also crap-tastic now. I'm getting low 40s. I used to get mid 50s.
If you rejetted for the cold start deal, maybe you should go to stock on the main and mid and keep the modified idle. Of course you have the K&N deal going on so you might want check for top end lean condition once you go back.
Again, I'd really like to see a dyno run on your setup, but not to the point of financing it. :)
Yeah yeah. I'm just gonna bump the main and mid main back to stock. I might even bump the pilot jet back to stock, but leave the screw to 3 turns out. The place I was gonna get my bike dynoed at closed, so no more $20 dyno runs for me. I'll find a new place eventually.
150 on a bike with K&N pod filter - no airbox and pipe.
125 on a stock.
127.5 on a K&N in airbox.
89-00 bikes.
Cool.
Srinath.
One of these might be semi-near you.
http://www.dynojet.com/maps/bikedynos/tx.htm