So I got to the point where I tested the top speed of my baby after a few thousand km's of 'getting to know each other better'.
Of course I did this on a closed circuit
So, many people say that top speed should be somewhere around 180 km/h - between 110 and 115 mph.
Well, I weigh around 85 kg (190 pounds?) without gear, and my top speed was 170 km/h - that's almost exactly 105 mph.
Bike has around 54k km's - 33k miles on it now. PO stated that it would reach 9k rpm in 6th gear, which would be 180 km/h, as I have stock gearing. He last rode it around 51k km's, but could be he tested top speed waaay before that.
Any opinions? Should I be looking around for anything to fix here, or is there nothing wrong?
Thanks for the input

To be fair it could be that the po is full of sh1t 

Based on experience....

With stick gearing, the mph to rpm is a 1:1. That is, 6k rpm is right about 60 mph. Seems pretty consistent across all my GS500's.

So based on experience, that would mean 11krom (red line) would be about 110 mph.

I recall that is about what the spec's say. Though I've only had one over 100mpd once, and it didn't seem to mind it. The GSXR's were surprised I kept up with them. (I can't say what happens when I loan one out).

I was able to hit 103mph GPS confirmed at the track. That probably works out to about 110 on the speedo. The last 10 miles per hour is really hard to obtain. Expect to spend 30+ seconds wot to go from 110 to 115.

Maintenance can have a huge impact on top speed, much more so than milage. Valve adjustment, chain condition, and air filter will have an impact on top speed. Valves will go out of adjustment in 5000-10000 miles unless you use gsjacks recommended clearances.

FYI: its very rare to hit top speed on a closed course, unless you somehow manage to get track time at a NASCAR venue.

With stock sprockets and stock size tires the speedo and tach match in 5th gear, 6000 rpm @ 60 mph or close to it.  In 6th gear both my 97 and 02 GSs showed about 4800 rpm @ 60 mph indicated.  Original road test in May 89 Cycle mag specs 4730 @ 60 mph.  GS would have to hit theoretical 140 mph to redline in 6th.



Only opened up the 97 once in the mountains of upstate NY, it hit 110 mph indicated so probably was just over an honest 100 mph carrying 240# me and a big Plexi 2 shield.  My 97 had about 55k miles on it then.  Never had the 02 over 80-90 mph travelling on the Interstate.  My list of data from all published road tests I've found shows top speeds ranging from 99-111 mph over the years.  The V&H modified bike reported a 121 mph top speed.

http://www.gs500.net/gallery/data/500/GS500tests.jpg

With my 134kg (geared up) now..   or my 142kg (geared up and last year), with stock sprockets, in 6th all I could get was 172ish (indicated), drop it to 5th and let it wind up to hover just under 11k I got 185 indicated. .. wind resistance killed it in 6th gear! (Plus my weight made accell above 170 indicated very tedious)

sent by willpower and a phone

Oh and same roa..   err track with very similar weather conditions

sent by willpower and a phone

Headwind or tail wind makes a huge difference, BTW.

My 48k bike was noticeably down on power, acceleration, gas mileage and top speed compared to the other young-un's I had in the 10 years I had that one. It was noticeably down on power compared to itself @ 8k.

@ 8K It would easily make 100 indicated, give me 50+ gas mileage.
@ 48k I was struggling to make about 90 indicated and would make 35-38 mpg. Of course I gained about 10 lb in that window, but the bike probably also gained 10 with billet this and corbin that.

Compared to the spring chickens I had in that time frame particularly the 90 I bought in 98 and hauled to canada and Cheesy/Tarzan boy's 89 and the crash/rebuild I bought in 2008 were the stalwarts.

Cool.
Buddha.

Thanks for all the replies!
IIRC there wasn't much wind that day.
I have to admit though, that replacing the chain, sprockets, and air filter is on my to-do list for this spring.
Overall fuel consumption is 4l/100km or ~58.8MPG thus far.

Try both directions on the same road. Wind resistance is the killer.

Mine will do 180km/h in 5th - almost at redline, but will stop at about 170-175 in 6th (similar to janx's experience), no matter how much you lay on the tank.

It flies to 160 no problem, but that last 20km/h takes a LONG time.

Physics!

Air drag is the square of the speed...so twice the speed = 4 x the drag

But its worse....

Horsepower required is the cube of the speed...so twice the speed requires 8x the horsepower.

What this means is the HP required curve gets really really steep as you get over the 100 mph range.  It takes huge increase in HP just to go a tiny bit faster.

Motorcycles, even with fairing seem to have quite a high drag coefficient  even if you "tuck".

The secret to going faster with a fixed amount of HP is to lessen air drag somehow.  Not easy on GS500.

It is also logical that the GS500 goes faster in 5th gear than it does in 6th.  The  engine produces the most HP at or near redline.  5th is the highest gear which still allows the engine to rev up all the way to the max HP point.  6th gear is in effect an "overdrive" for cruising at relatively high speeds while keeping the engine  below redline.  I suppose that with a strong tailwind, or a down hill stretch the GS would go faster in 6th than in 5th.

BTW the above supoorts my assertion that the stock gearing on the GS was designed "just right"...


Cookie

Quote from: Wagoneer on March 11, 2014, 05:14:14 PM
Try both directions on the same road. Wind resistance is the killer.

Mine will do 180km/h in 5th - almost at redline, but will stop at about 170-175 in 6th (similar to janx's experience), no matter how much you lay on the tank.

It flies to 160 no problem, but that last 20km/h takes a LONG time.

Stock GS500 reaches max HP at about 8500 rpm and drops way off before 11k redline.  Won't reach redline in 5th or 6th gear but does reach max HP in 5th and 6th near 100-110 mph top speed.

Ok so if max HP comes at 8500 and you can hit 8500 in 5th and 6 th...then it would seem the bike would go its fastest in sixth at 8500

But the chart shows 5th at 11,000 a bit faster, as most have experienced.....

But...are we confusing HP of the engine with HP AT THE REAR WHEEL???

I contend that whatever the gear...when the bike is going its fastest...the HP at the rear wheel is its greatest.........i.e...less HP can't make more speed!

Cookie

Quote from: gsJack on March 11, 2014, 06:14:23 PM
Stock GS500 reaches max HP at about 8500 rpm and drops way off before 11k redline.  Won't reach redline in 5th or 6th gear but does reach max HP in 5th and 6th near 100-110 mph top speed.

http://www.borynack.com/xr650r/Horsepower2speed_files/image002.jpg

here's the chart that show how much HP it takes to go faster......

Cookie

i dunno about all the tech stuff... just that if in 6th on a flat road with no particular headwind or tailwind and me tucked in as much as i am able (which is less than a skinny guy!!), then it kinda topped out with the needle just over 170 .. kinda like bumping into a highspeed mattress though rather than 'hitting the wall' ...

click it down to 5th and screw the throttle again... needle kept climbing over 180 .. then slowly to 185 or "maybe" 190? .. i was concentrating on being tucked while still watching the road etc ... the rpm similarly were near 11k .. dont know exactly how much under .. but only a needle width or 2 at the most!?

also a note that original heavy weight test was standard fairing and screen , while recent 'light weight' test has a ZG Touring screen on... the road... dammit... track in question is approx 450m above sea level... and im still using E10 as i was then... from the same place i pretty much always get it.. (unless i am incredibly rarely lucky to have to ride far enough away to fuel up somewhere else!  )

not disputing anyones data!!!!! ... just mentioning my experiences on my bike....

final footnote... 180ish on the GS500 seems like you about to leave smoky/flaming tyre tracks on the ashphalt (Back to the Future style) ... and last time i got on anything faster, it was several to many segments on the dial faster!! .. but cos the bike at the time was so much more gutsy .. and got up there pretty easily... somehow it didnt "feel as fast!" ... or maybe my younger brain just refused to take in the danger quotient? 

Quote from: twocool on March 11, 2014, 05:31:07 PM.......................The  engine produces the most HP at or near redline.....................

I'm just pointing out once again that the stock GS engine does not produce the most HP at or near it's redline.  It peaks at 8500 rpm and falls way off before it's 11k rpm redline.  It does reach it's top speed at or near it's max HP though.  We did this dance once before so I'm out of here. 

yes, the engine produces the most HP at 8500 as per specs.  Redline is 11000....

But using Janx experiment...he went 172 in 6 th and sped up to 185 in 5 th

If you look a the HP vs speed chart, and use the purple drag curve (which seems to fit the GS)..

I converted Kilometers per hour to MPH, and reduced for indicated error


So let's say he went 93 MPH in 6th...and 99MPH in 5th

the chart indicates 30HP being produced to go 93MPH
the chart indicates 35HP being produced to go 99 MPH

So, in fact, the bike goes faster in 5th...and 5 extra HP are being produced by down shifting and going to redline.

You can't go faster by producing LESS horsepower....


\Cookie

Quote from: gsJack on March 11, 2014, 09:34:07 PM

Quote from: twocool on March 11, 2014, 05:31:07 PM.......................The  engine produces the most HP at or near redline.....................

I'm just pointing out once again that the stock GS engine does not produce the most HP at or near it's redline.  It peaks at 8500 rpm and falls way off before it's 11k rpm redline.  It does reach it's top speed at or near it's max HP though.  We did this dance once before so I'm out of here.

I've been through the math on this a bunch of times. HP is the most important figure when you're looking at engine performance. However, the torque chart is what you want to look at when determining driving force.

As we all learned in 7th grade physics, you can always trade speed for force using a simple machine. HP is a meaningful figure on engines, because it combines how fast the engine can spin with how much force it produces while spinning. You can compare two engines based on their HP curves, even if those two engines are a 2.5 liter V6 making 200ft/lbs of torque and a 1 liter I4 making about 70ft/lbs of torque.

When it comes to pushing the bike forward, the only factor that matters is how much force is being applied to the rear wheel. When two gears both put the engine in the power band, a lower gear will almost always provide more driving force, simply because it trades more of the engines rotational speed for force than the higher gear.

On a lot of bikes, 6th is geared for low cruising RPM. With the GS500, 5th is going to tend to produce better top speed.

Speedo is also +8% high, Garmin Certified, at least mine was.