What gearing for 18 inch rear tires

[KFX400 RACER]

I have 18 inch tires on the back of my 250R and I do not know if I have stock size sprockets or not.

What size sprockets should I be running for 18 inch mx tires for mx racing.

It seems like it revs very fast and you have to shift from 1st, 2nd, and 3rd very fast almost one right after another.

Thanks

[86 Quad R]

you should easily be able to run a 14/36 with out any trouble.

[KFX400 RACER]

I went out and checked my gearing. I am running a 12 tooth sprocket in the front. I figured it may be a 12 tooth sprocket from the 250 dirtbike back then. The rear sprocket is 39. I never checked since I bought it about a year and a half ago.

Man that is why I have to shift so fast. I have to order a 14 and 36 then I should feel a major difference.

Thanks,
Jake

[deathman53]

I use a 14/38 w/ 18" tires. 36 is too much for other than a worked motor. I can use 14/36 on my motors(310pv, cr igntion, pipes, 39 pwk carbs, cr reeds and more), but doing mx you really don't need the top end the 36 will give you and it takes away at the bottom end.

[matt250r21]

I run 14/36 for MX. Try a 14 for the front and experiment with rear sprockets. 39-36 till you find what you like.

[2StrokeGod]

I have a renthal 37 with one ride on it pm me if interested.