Sprocket interchangeability KDX250 / Kx250

[43Duc748]

I'm due to replace the sprockets on my KDX250. The local shops say they'll have to order the sprockets because they don't show in their guidebooks. I'm sure there's got to be some compatibility between the bikes.

Also, my current gearing is 14 / 48. If I go to a 13 front w/ a 48 rear, what benefit will I realize? More low-end grunt for trails is my guess, but will I give up top speed? I've seen 13 / 50 recommended as well. Any thoughts?

On other thing, my local shop as a steel front sprocket, but only aluminum rears, I'd like to stay w/ steel for the rear as well, but if I have to go w/ the alum, is there a problem w/ steel / alumin?

 

[dirt bike dave]

I geared mine 13/48 for trail use, and would use 14/48 or even 15/48 for dual sport runs.

With 13/48 you will have plenty of top speed for trails and improved lugging ability in the lower gears. Great if you ride tight trails.

I don't think the KDX250 sprockets are very rare or exotic. I think there is interchangeability with late '80s early '90s KX250 and maybe even KDX200. The motor is based on an '88 KX250, so that should help with the countershaft. Sounds like you need to find someone who has a more complete listing of bikes in their sprocket catalogs.

On mine, I found if I ran a 13t I could remove two links from the chain and move the wheel all the way forward in the adjusters. This shortens the wheelbase and helps with turning.

 

[Canadian Dave]

Steel rear sprockets are going to last MUCH longer than aluminium particularly is you are riding in gritty conditions like sand, mud etc.

Finding sprockets should be a problem, the KDX200/220 sprockets (front and rear) will fit right on as will KX sprockets from the same era.

David

 

[43Duc748]

I had to order some from my local supply shop. They only had alum so had to order the steel. I'll take the down time to go ahead and get my front wheel re-built.... Took the bike for a quick spin up and down the street and was getting seasick from the wobble!

 

[bad96z71]

although i just got it put togather my 92 kdx250 is a brute with 14/48 i believe, there is no issues with power to climb it will lug as well as a 4 stroke up them hills although 13/48 would work well also

 

[43Duc748]

I ordered the 13. Figured I'd see how that is for a while. I'm not a big top-speed guy, so it should be great for me.

 

[43Duc748]

On mine, I found if I ran a 13t I could remove two links from the chain and move the wheel all the way forward in the adjusters. This shortens the wheelbase and helps with turning.

Hey DB Dave, I'm going to run the 13/48 at your suggestion. Do you remember how many links you ran on your chain? I know it's a long shot, but I thought I'd ask!

 

[dirt bike dave]

Sorry, I can't remember exactly. I think it was 2 less than stock. I shortened a chain that was already broken in. A brand new chain right out of the box might be just a little too tight.

FWIW, I also ran no pre-load on the front fork springs to help the front dive down a little when cornering. The bike has pretty slow steering geometry, so you need to get creative. Cutting the front of the seat foam really helped the riding position and allows you to get forward for cornering, so if you have not done that yet, that is another thing to look into.