Total Motorcycle Community Forums

hey guys/gals. i have a K2 gixxer 1000 and want to push 200mph.
i am starting the work on the bike to make it possible but even with yoshi exhaust, Power Commander, K&N filter, and top speed derestrictor.. im not sure if the gearing is up for it. how much will one tooth off the countershaft give me at that speed?
also, as far as nitrous kits.. is there a setup that any of you recommend?
thanks.
- Herzeleid

a front sprocket getting smaller lessens the top speed in each gear. go smaller in the rear for top speed.

^^^^^ if he's running out of power before hitting redline, he would get higher top speed by dropping a tooth. Otherwise it will have the opposite effect of what he's looking for.

I'm going to assume you're not running out of gear (engine redlining) before topping out, so a tooth off the front sprocket will net you about, uhh, I think 1.5 teeth increase in the rear. There should be calculators online, or in spreadsheet form, that can tell you top speeds with current gearing. From that you can change values and see what your ground speed will be at with modified gearing. Try checking out GSXR forums for one. I'm almost certain there's one out there. If not, and you're feeling industrious, you can make your own. Gear ratios and tire dimisions are all easily found, along with the other information you require.

My Radian's spreadsheet has the following values:
Engine speed (RPMs)
primary drive ratio
gearing for gears one through six
front and rear sprocket count
final drive ratio
tire diameter and circumference

Calculation:
RPM / Primary Ratio / Countershaft Ratio / Final Drive Ratio * Tire Circumference(in feet) * 60 / 5280 = MPH

To be honest, I don't think that a lot of our members would really know what to do to help you out. But it sounds like you're on the right track.

Dropping one tooth in the front will definately increase your top speed, but it'll hurt the acceleration.

Be careful out there though, I'd hate to see you on the news.

Increase the front sprocket tooth count and drop the rear sprocket tooth count for increase in top speed but a decrease in initial acceleration. Sometimes though the bike will not rev to the max limit when this is done and thus you may end up with only a 5mph gain overall.

Another place to look for an increase in speed is finding any kind of limiter and removing it. Increase air flow to the engine, increase exhaust flow to let the engine breathe easier.

Expensive options are to increase the compression ratio with higher compression cams and pistons and maybe also a flywheel change.

Be good, don't goof, squids give us a bad name as it is.

you can't do it w/o a TRE.

TRE will limit it to 186mph in 6th gear, unless you can magically make it run 200+ in 5th gear.

and i really doubt you can push it to 200+ w/ just a sprocket change.

i have a TRE installed on the bike already.. the bike is capable of going faster than 186, but im worried if i change the gearing too much that it will not be able to reach its redline. that info should help quite a bit though, thanks.
- Herzeleid

The question on my mind is... *WHERE* are you trying to hit 200 at? Bonneville? Maxton? The setup of the track you're going to use plays a *BIG* part in what you need to do to the bike.

VermilionX wrote:you can't do it w/o a TRE.

TRE will limit it to 186mph in 6th gear, unless you can magically make it run 200+ in 5th gear.

There is nothing magic about boatloads of power and different gearing.

Speed in that range is dictated mostly by aerodynamics; nothing else (although red bikes have been proven fastest in clinical trials ). Add enough horsepower and I suppose 200 is possible BUT it would be much simpler and cheaper to improve either your frontal area (tuck in) or improve your drag coefficient (get a PhD in CFD).

Basically, to double your speed you need an 8x increase in power. Max speed based on available hp is based on the following formula:

Vmax=56.44(maxhp/(Cd*A))^(1/3)

maxhp = max horse power (hp)
Cd = coefficient of drag (unitless)
A = frontal area of bike + rider (square feet)

Put this in Excel, fiddle with the numbers and you'll see how a small change in Cd will have a large effect on top speed.

Enjoy