I have had my 09 klx now for A couple weeks now and I am finding the seat very hard and uncomfortable after a while of riding is there anywhere that makes a better seat for these bikes.

also the bike has stock gearing right now and I like the low end that it has right now but would like to get alittle more top end is this even possible to have good low end and top end. whats the common gearing everyone is using?

 

"Seat Concepts" sells a replacement foam and cover that is a worthwhile upgrade.
The stock gearing is probably as close to what you want that you're going to get. Drop a tooth on the front and you'll lose top end. Add a tooth up front and you'll lose low end.

 

Are you sure you'll loose top end if you drop one counter tooth. I am running a 13, the rpm's pretty much match the speed x 110. I never hits redline in top gear.

 

It seems to me if you're trying to maximize velocity, you should not get to redline. But rather max velocity would occur just a little past the peak of the HP curve. If you can get to redline, where power has dropped way off, then a taller gear should get you faster.

Just thinking in theoreticals here.

 

The supermoto version uses a 39t rear with a 14t counter shaft sprocket. There is a 15t counter shaft sprocket that will fit as a bolt on. That is as tall as it gets without some work beyond bolt on.

According to my spreadsheet if the tire is 26.1" diameter (this will vary depending on brand) the speed a 8200 rpm (max hp) would be about 80 mph with the 14/42 versus about 92 mph with the 15/39 using the gear ratios for a 2009 KLX250.

Again, this is calculated at the max power, not at 10,000 rpm and I don't know if the bike can push that much air.

It takes four times the power to go twice as fast due to aerodynamic drag.

 

Aerodynamic drag? You think the KLX has aerodynamic drag? I've seen land speed record vehicles that weren't as slick as the exalted KLX.

 

The KLX doesn't have ANY aerodynamic drag. It's the nut at the handlebars that's the drag.

 

1. is the 15/39 a typo?
2. 92 really?
3. is this about a supermoto or 's'?

 

I've hit 96mph indicated, not gps, after drafting an 18wheeler, with stock gearing on a stock bike, carrying saddlebags(I think they helped with the draft pull effect). I could actually keep it at 96 once I got there, but once back to 83 or so(normal top speed), she would not go back up above that.
That all happened in a 70mph zone with 2 lanes of traffic, I had to give her all she had, for quite awhile. 18 ponies, or whatever it is, ain't enough in that situation.

 

Not a typo he said supermoto version at the beginning of his post

I got to 98 indicated downhill on the stock bike, fastest its ever been haha