I was curious about how the speed of the KLX250 was affected by gearing, tire sizing, etc. I know about gearing commander but wanted to work out the calculations myself.

I created a google sheet if anyone would like use it.
Speed Sheet

I have a GPS and eventually want to correlate my indicated speed to my GPS.
Long term, maybe add actual data from users to help others when a speed issue arises.

Any thoughts out there?

 

i know that the stock gearing is a little low for the power output of the engine

i know that i went taller and had the bike actually hit the red line 10500 rpms

that was using 14t F / 48t R i think i was going 10500 @ 70

stock was allmost 14t F / 42t R 70 @ 7000 topped out @ 8200 rpms

im thinking if someone went 14t F / 44t R they should be able to hit well over 90 (theory)

but i believe i heard add 300 rpms per tooth in the rear

 

Looks pretty similar to the Gearing Commander

Gearing Commander: Motorcycle Speed, RPM, Chain & Sprockets Calculator

 

For every tooth added or subtracted from the original 42 tooth rear changes the ratio by 2.3%. (.023)

So is you are going 70 MPH with stock rear and the engine is at 7000RPM. Then if you change out to a 45 (3 teeth larger) your RPM will be 7000 times 6.9% (2.3% x 3 teeth) equals 7483 rpm.

 

I would say it is a little high for stock power.

 

Yeah, zippets had it backwards. Low gearing is like first gear. Tall is like 6th.

I find the stock 14/42 gearing slightly too tall for the trail but want a taller gearing for the highway so I'm leaving it alone. Why on earth they didn't make 6th gear much taller I'll never know. We have a close ratio transmission but at least there are 6 gears.

 

I fully agree with this: if 5 and 6 were more separated, we could gear it lower (ex: 14/46 or so) and still have reasonable rpm at highway speeds. That would be the best of both worlds: good for trails and highway. 5 and 6 are so close anyway that a little more separation would not be an annoyance.

It strikes me that Kawasaki did the reverse for the 09 and later, compared to 06-07: they made 5 and 6 closer, aggravating the situation. Apparently they thought not so many customers would have agreed with my views...