My naked '01 GS500 would normally cruise easily at 85 mph (indicated) and go over 100 mph, but this afternoon on the freeway against a stiff headwind, it topped out at a steady 6,500 rpm in 6th gear, 75 mph, with the throttle wide open. That gave me a real lesson on aerodynamics, wind resistance and horse power. I never expected or experienced drag-limited top speed at only 75 mph. I guess if the headwind was blow at 30 mph, then my effective "air speed" was 105 mph.

I also own a YZF600R and a SV650, so the GS is beginning to feel too weak to me...

Same exact thing happened to me on my way home from work today.  I just down shifted into 5th to power through it. 

even in a hard headwind my gs will go over 100, just barely though. normally with a 16t sprocket my bike will redline in 6th at 130ish, with the 15t 120-125.

When I used to bicycle downtown everyday there was one long strip about 20 blocks long that was just flat and straight. I'd usually average 20mph, closer to 25 if I had a good breakfast, but there were days that I'd get a headwind and seriously crawl the entire way at like 6mph. Even worse was when you were already cruising at 20mph, and you get this instand burst of wind in your face and just drop from 20mph to 5mph instantly. It's soul crushing.

Quote from: black and silver twin on April 29, 2010, 10:49:23 PM
even in a hard headwind my gs will go over 100, just barely though. normally with a 16t sprocket my bike will redline in 6th at 130ish, with the 15t 120-125.

130ish on a GS w/ <40 hp? I thought the top speed of GS was drag-limited to about 105-110ish, not gearing limited.

I also read the SV650, with about 70 hp, tops out at about 135. And a 600cc supersport with about 100 hp tops out at about 150.

ive been considering taking off my fairing and going nake bike for awhile now.  Hearing this make me kinda think again,  i wasnt sure if it made that much of a difference i guess i could just try it out.  top speed doesnt matter in the twisties anyway

Quote from: Gary856 on April 30, 2010, 12:06:06 PM
130ish on a GS w/ <40 hp? I thought the top speed of GS was drag-limited to about 105-110ish, not gearing limited.

I would believe 130... Hell I've done 115 up hill in 5th gear into the wind.  The other day I was going 125 downhill with a lot of wind.. it was a bit scary to be honest.  But seriously.. 40mph head wind @ 75 in 6th gear (6k rpm) was all she had WOT.  Downshifted into 5th got her up to 85 and back into 6th it was pretty much "normal."

Quote from: Gary856 on April 30, 2010, 12:06:06 PM

Quote from: black and silver twin on April 29, 2010, 10:49:23 PM
even in a hard headwind my gs will go over 100, just barely though. normally with a 16t sprocket my bike will redline in 6th at 130ish, with the 15t 120-125.

130ish on a GS w/ <40 hp? I thought the top speed of GS was drag-limited to about 105-110ish, not gearing limited.

I also read the SV650, with about 70 hp, tops out at about 135. And a 600cc supersport with about 100 hp tops out at about 150.

Look at my list of mods, my bike makes a dyno proven 44whp (5 over stock, or 13%). also the powerband has been pushed up 700 rpm. my new peak horsepower rpm is 10000. believe me it will redline in 6th with a 16t sprocket at 130mph, when the bike was bone stock it would go 114mph.

and no, a ninja 600 will go over 160 easly, my brother has one and when I rode it i took it to 160 and still had throttle left, it was still pulling hard.

If anyone's claims for top speed are relying on the stock speedo, then we're not comparing apples with apples. Stock speedo on my bike overreads 10% checked by GPS. There must be some variation out there.
I don't believe a basically stock GS will do more than 110 mph on a flat road with no wind. If you think yours does, check the speedo with a GPS!

Quote from: black and silver twin on April 30, 2010, 11:42:54 PM

Quote from: Gary856 on April 30, 2010, 12:06:06 PM

Quote from: black and silver twin on April 29, 2010, 10:49:23 PM
even in a hard headwind my gs will go over 100, just barely though. normally with a 16t sprocket my bike will redline in 6th at 130ish, with the 15t 120-125.

130ish on a GS w/ <40 hp? I thought the top speed of GS was drag-limited to about 105-110ish, not gearing limited.

I also read the SV650, with about 70 hp, tops out at about 135. And a 600cc supersport with about 100 hp tops out at about 150.

Look at my list of mods, my bike makes a dyno proven 44whp (5 over stock, or 13%). also the powerband has been pushed up 700 rpm. my new peak horsepower rpm is 10000. believe me it will redline in 6th with a 16t sprocket at 130mph, when the bike was bone stock it would go 114mph.

and no, a ninja 600 will go over 160 easly, my brother has one and when I rode it i took it to 160 and still had throttle left, it was still pulling hard.

watch that peak hp rpm homie, 10k is valve float time.....

that being said, 130 indicated is around 110 GPS. depends on our front tire size. full tuck, 110 pound rider, downhill, with a full canopy salt flat racer fairing, with grease on it, ya, mayyyyybe 130. otherwise, no.

as far as 160 on a neenja 600, sure, but you're going to want to GPS it.

either way, anything above 80 is asking for death or worse on a motorcycle. slow down and hit the twisties friend.

According to google maps my ride to work is 46 miles down and 46.5 miles back (different route coming home.)  My odometer says I went 93.9 miles. (Plus a mile from the gas station the night before.)  To me this says my speedometer is reading just a LITTLE slow.. but really close.

Quote from: Elijafir on May 01, 2010, 07:02:14 AM
According to google maps my ride to work is 46 miles down and 46.5 miles back (different route coming home.)  My odometer says I went 93.9 miles. (Plus a mile from the gas station the night before.)  To me this says my speedometer is reading just a LITTLE slow.. but really close.

speedos are generally off ten percent from the factory. this is why poloice have no patienzce for speeding.

speedometer readings and odometer readings are not both geared. 10 percent off. odometers are very accurate, as otherwise your car/bike would only register 100000 miles when it actually traveled 110 or 120000 miles. then factor in afrermaket wheels on a car, and there is a serious distance difference.

you've just proven 1/2 of my point with Google maps. I've proven it myself with two tomtom GPS, a Iggy, and now my nexus, all GPS devices. our car is actually 12% off, meaning
100 MPH indicated is actually around 89 MPH. SOOOOO, Mr police officer knows if he clocks you at 89, your speedo registered close to 100, and that's no where near any speed limit in the usofa.

keep it in mind while you're out playing the bike.

either way, anything above 80 is asking for death or worse on a motorcycle. slow down and hit the twisties friend.
[/quote]
You have hit the nail on the head.  The GS is a lot of fun in the twisties in the hands of a competent rider that knows how to use the gear box.  It can give alot of big bikes a run for their money.  Topping out on it is very dangerous as the bike lacks a steering stabilizer and will easily go into a high speed wobble.
I have put about 50K miles on a 93 GS500 and I have had my fare share of going down on it, including a close encounter with death at about 80 MPH. 

Ride safe on any bike and live to ride another day.

Getting back to the original problem.............

A letter in the service section of the Jan issue of CW mag said:

...............I own a 2000 Suzuki GS500...............Most of the time it runs flawlessly, but it's had a quirk...................When I encounter exceptionally windy conditions, the engine often stumbles and sputters as if starving for fuel................The moment the gust lets up, the engine immediately settles back down and runs fine.........................The bike is absolutely stock........

To which CW gave a long winded answer about being too lean and rejetting, etc, etc...........

Follow up in latest June issue of CW:

In the ...Jan issue, TA described a problem with his GS500........I've had this same problem with two of my bikes........82 GS850GLZ........84 CB700SC.  I resolved the problem on both bikes by rerouting the carb float bowl vent tubes to keep them out of the wind..............

Something to think about, I find it very difficult to believe this is just a head wind problem posted by the OP.  I had my 97 GS500 up to 110 mph indicated with a Plexi 2 shield and my 250# butt on it.

Quote from: ohgood on May 01, 2010, 08:45:39 AM

speedometer readings and odometer readings are not both geared. 10 percent off. odometers are very accurate, as otherwise your car/bike would only register 100000 miles when it actually traveled 110 or 120000 miles. then factor in afrermaket wheels on a car, and there is a serious distance difference.

So the fact that my "Very accurate" odometer is approximately .6mi OFF of what it should be after only ~100 miles doesn't mean anything?  The fact that the speedometer and odometer are driven by the same cable doesn't mean that they should be in sync?  According to what you're saying If I am going 100mph indicated for one hour my odometer should read ~90 miles?  And furthermore.. with all the mathematical calculations that go into building motor vehicles why would "All speedometers" be off 10%?  A conspiracy to keep you going slower than you think you are?  How do you know that your GPS units aren't 10% off because they measure your longitudinal and latitudinal speeds.. and don't take in to account your change in elevation?  Or do GPS factor that in?  I've never had one.. so I don't know THAT Much about them.  Also, I've been pulled over plenty of times where the officer said my speed was what my speedometer said.. all cops know about this 10% issue and factor that in so they can give you bigger tickets?
HARD TO BELIEVE.

I do know that me going 75mph indicated at 6krpm in 6th gear and not being able to accelerate was purely because of the head wind and not some vacuum issue.. because i could down shift.. get up to 80-85.. shift back in to 6th.. and then have enough power to accelerate in 6th again. 

Quote from: Elijafir on May 01, 2010, 02:43:47 PM

Quote from: ohgood on May 01, 2010, 08:45:39 AM

speedometer readings and odometer readings are not both geared. 10 percent off. odometers are very accurate, as otherwise your car/bike would only register 100000 miles when it actually traveled 110 or 120000 miles. then factor in afrermaket wheels on a car, and there is a serious distance difference.

So the fact that my "Very accurate" odometer is approximately .6mi OFF of what it should be after only ~100 miles doesn't mean anything?  The fact that the speedometer and odometer are driven by the same cable doesn't mean that they should be in sync?  According to what you're saying If I am going 100mph indicated for one hour my odometer should read ~90 miles?  And furthermore.. with all the mathematical calculations that go into building motor vehicles why would "All speedometers" be off 10%?  A conspiracy to keep you going slower than you think you are?  How do you know that your GPS units aren't 10% off because they measure your longitudinal and latitudinal speeds.. and don't take in to account your change in elevation?  Or do GPS factor that in?  I've never had one.. so I don't know THAT Much about them.  Also, I've been pulled over plenty of times where the officer said my speed was what my speedometer said.. all cops know about this 10% issue and factor that in so they can give you bigger tickets?
HARD TO BELIEVE.

I do know that me going 75mph indicated at 6krpm in 6th gear and not being able to accelerate was purely because of the head wind and not some vacuum issue.. because i could down shift.. get up to 80-85.. shift back in to 6th.. and then have enough power to accelerate in 6th again. 

i believe the 10% was originally to keep the manufacturers of cars out of the hot seat... imagine selling cars with speedos that registered SLOWER than your actual speed:

you get a ticket for 70 in a 55, and 1 million other people sue the auto maker for providing them, the buyer, with a speedo that was incorrect and allowed them to speed, unknowingly.

i won't say it's common knowledge, but it's quite common.

the camrys: indicated 70 mph = actual 63 mph (gps or phone phone is agps iirc accurate within 7 meters)
the hondawagoon: indicated 70 mph = actual 65 mph (gps or phone, phone is agps iirc accurate within 7 meters)
the pickup: indicated 70 mph = actual 70 mph.... this vehicle does not have stock wheels/tires. they are a little bit bitter than stock... leading to lower readings. tiny tires = faster reading... huge tires = slower reading.

i've tested the speedos on the trucks @ work, and the chevys are all 10% fast indicated, while the fords are about 10-12.

now, keep in mind the odometer can read whatever it's geared to read, and the speedomteter the same. they don't have to coincide exactly. if one is geared to read 1% or 30% higher than actual, it's not difficult for a few engineers.

***

the part about the breather (over flow? ) line makes sense. i wish i had a running bike to test it on right now. or just to ride.

If you want to check it out yourself, do a Distance/Time test.

Find a section of highway and measure off, say, 10 miles. Ride at 60mph for ten minutes. Check your trip meter. Does it say 10 miles? Did the ten miles take ten minutes at 60?

Some highways around here the council have put distance markers. They do this for 5 clicks. And each click is another marker letting you know. As you ride/drive you check your Odo or trip at the 1st sign and at each sign thereafter and at the end. Lets you know how far out it is. My GS is accurate in the distance. I didn't time it Exactly, but the time seems about right too - certainly not out by 10 %

If you still doubt your bike's indicated speed, call the cops and ask them where you can get motorcycle speedo's calibrated. Then go there and have it checked for real. Cause if you get done for speeding and you take it to court, one of the 1st things you'll be asked is "When did you have your speedo calibrated last".

Now. There is a chance, that Speedos, Odos, etc., have to abide by a particular country's Standards. So what applies in Aust might not apply in the USA. I know that regardless, my car's indicated speed is within 1kph of what the GPS says. But I put this down to elevation changes which my GPS does not factor in as it only factors linear speed.

Michael

Quote from: mister on May 01, 2010, 04:11:08 PM
If you want to check it out yourself, do a Distance/Time test.

Find a section of highway and measure off, say, 10 miles. Ride at 60mph for ten minutes. Check your trip meter. Does it say 10 miles? Did the ten miles take ten minutes at 60?

Some highways around here the council have put distance markers. They do this for 5 clicks. And each click is another marker letting you know. As you ride/drive you check your Odo or trip at the 1st sign and at each sign thereafter and at the end. Lets you know how far out it is. My GS is accurate in the distance. I didn't time it Exactly, but the time seems about right too - certainly not out by 10 %

If you still doubt your bike's indicated speed, call the cops and ask them where you can get motorcycle speedo's calibrated. Then go there and have it checked for real. Cause if you get done for speeding and you take it to court, one of the 1st things you'll be asked is "When did you have your speedo calibrated last".

Now. There is a chance, that Speedos, Odos, etc., have to abide by a particular country's Standards. So what applies in Aust might not apply in the USA. I know that regardless, my car's indicated speed is within 1kph of what the GPS says. But I put this down to elevation changes which my GPS does not factor in as it only factors linear speed.

Michael

i wondered about this, and wikipedia has some interesting bits...

http://en.wikipedia.org/wiki/Speedometer

Error

Most speedometers have tolerances of some 10% plus or minus due to wear on tires as it occurs. Additional sources of error are; tire diameter variations due to temperature, pressure, vehicle load, and nominal tire size.

Modern speedometers are said to be accurate within 10% but as this is legislated accuracy, this may not be entirely correct. This can make it difficult to accurately stay on the speed limits imposed; most countries allow for this known variance when using RADAR to measure speed, although levels of some 3 km/h or 3% are also used in areas of tough enforcement (e.g. Victoria, Australia). This causes many arguments due to motorists complaining that they were not doing the speed as reported. Revenue[3] is being increasingly blamed for these stricter measures. There are strict United Nations standards in place but it seems not being enforced in some countries, as cars not adhering to United Nations standards, are imported from these, leaving this matter in limbo. Motorists are open to charges of speeding, if harsh methods 3% or 3 KPH are used using a speedometer not complying with accuracy standards.

Excessive speedometer error after manufacture can come from several causes but most commonly is due to nonstandard tire diameter, in which case the

    percent error = 100x("standard diameter"/"new diameter" - 1).

ERRATUM: Percent error = (standard diameter – new diameter) / standard diameter * 100% This is a variation of the standard percent error formula. The one above is incorrect.

Nearly all tires now have their size shown as "T/A_W" on the side of the tire (See: Tire code), and the tire's

    diameter in inches = TxA/1270 + W.

For example, a standard tire is "185/70R14" with diameter = 185x70/1270 + 14 = 24.20 in. Another is "195/50R15" with 195x50/1270 + 15 = 22.68 in. Replacing the first tire (and wheels) with the second (on 15" wheels), a speedometer reads 24.19/22.68 = 1.0670 times the correct speed or 6.7% too high.

ERRATUM: Using the correct formula for percent error, we conclude that the speedometer will read (24.20 – 22.68) / 24.20 * 100% = 6.28% too high e.g. at an actual speed of 60 MPH, the speedometer will indicate 60 + (60 * 0.0628) = 63.77 MPH (approx).

**** the really interesting part is tire diameter.... but i'll bet johnny law doesn't really care, so long as he has 22.3 more doughnuts and a shady spot to snarf them tomorrow morning

My GS is almost exactly 10% off when compared to GPS and radar.
My Honda NX650 is about 8% off.
I've always thought cars speedometers were a lot more accurate than motorcycles.

My Dodge Caravan actually understates my speed by about 5%, which is a little bit scary.

Thanks Ohgood.

Just about everyone down here knows of Victoria's 3kph rule. While the rest of the country doesn't seem to bother with up to 10kph over - BUT - will Strictly enforce School Zone speeds.

I think the reasoning is certainly one of Numbers. If they booked everyone who was speeeding but less than 10 over, they'd spend all their time in paperwork. But also, they (cops) know that people's speeds drift up and down as they watch the road, glance to the speedo, negotiate bends and curves and hills, back to the speedo, etc.

Two things about tire size...

Thing # 1: One of the guys we ride with has put a larger front tire on. When he leads rides, according to everyone behind him he is speeding. He never got his speedo recalibrated.

Thing # 2: Guy got new tires for his 4wd. He was, according to his speedo, sitting on 110kph. Got booked for speeding. Took it to court. Lost. Had his tires/speedo rechecked. Discovered the increased diameter. Had the Tech do the calculations of Old Diamterer to New Diameter to verify the claimed speed. His new tires with the increased diameter were giving him nearly 12% higher Actual Speeds. He went back to court to argue that he was trying to do the right thing, and that according to him he was only doing 110 as indicated. Judge told him that despite his Intention he was Still Actually Speeding and that it was His Responsibility to make sure the car's speedo was accurate.

So watch out for tire size.

Michael