top speed question?

[mineralgrey01gt]

Ok so I finally got a chance to GPS my 250r yesterday. I know im being slowed down by my 18" rears but I GPS'd 67mph. Does that sound about right with the mods in my sig? Im still on stock gearing, 13/39. I have a 14tooth for the front that I havent tried yet but im thinking about trying it out. The bike pulls hard up to about 55mph then it falls on its face the rest of the way up to 67mph

[deathman53]

that sounds about right, maybe even too fast. 18" tires kill your speed and a 39 tooth rear is 1 tooth more than the stock was. If I remember correctly, 20" tires, 13/38 gearing, it toped out at 72.

[pimpt250r]

stock gearing on 86/87 is 13-39

[mineralgrey01gt]

thanks a lot for the info. Im going to put my brothers 20" flattrack tires on it and see what it does with those on GPS. Im hoping to break into the 70's with it.

Would the 14T sprocket help me out any? If so im willing to try that to keep the 18" tires on it. Even though I love how the bike pulls right now

[86 Quad R]

it'll rip with a 14/38-39 gearing and 18" tires. :D

[mineralgrey01gt]

Originally posted by 86 Quad R
it'll rip with a 14/38-39 gearing and 18" tires. :D

Thanks!!!

[wilkin250r]

A 2-inch difference in tire size is a pretty big change, more than most people realize. 13/39 gearing on 20 inch tires is about the same drive ratio as 14/38 gearing with 18 inch tires.

So bumping that front sprocket up to 14, you'll end up just a little shorter than the stock drive ratio, it should perform pretty well for you.

[86 Quad R]

yes but the lesser rotational mass at the wheels, with great hooking tires will torque much better than a 13/39 with heavier 20" tire. :cool:

[timritchieblue]

i just changed my gearing from 12/38 to 12/36, WOW! big change, now mabee i can pass my buddys klf400, we were tied before. but, i would always get him on the turns, haha!

[baldathoR]

I haven't ridden a stock 250r that fell on it's face anywhere.

[pimpt250r]

http://home.earthlink.net/~gellett/250r.htm
courtesy of BLACKeR on another site he posted this

[bushwesl]

How would one estimate their maximum RPM level?

[pimpt250r]

I think its 8500 but the top of the estimator says 8250

[wes350x]

With 14/37 gearing and 18in rears I hit 75 on my GPS. I weigh 225 lbs. Thats way faster than I thought. Just bought the bike like it is with a curtis sparks built motor, runs on only 110+ fuel. What do you guys think my gearing is so high for on the bike, I know to possible compensate for the short rears. Never crossed my mine to look at the gear ratio when I bought it.

[timritchieblue]

put some 20's on their? you'll do 80mph!!!

[wes350x]

Yea, I will eventually put some 20in but I will also put a 13t front sprocket