Replacement carburetor for 2001 WR 426

Does anyone know how much work it would take to adapt a WR 250F or YZ 250F Carburetor for a stock WR 426 engine. I know they are 37mm carbs and the 426 is 39mm or 41mm, but could it fit and how much performance would I lose with this set up? I wouldn't mind if there would be a little more low end a little less top end. It seems like the 250 carbs always are a lot cheaper. Thanks!

Chug a beer through a cocktail straw. Thern chug one with out. Beleive it or not, that is the difference.

The smaller carb would be better in slow technical riding but above 1/2 throttle, it would be gutless.

Exterior dimensions of a 37 to 41 FCR is the same. The bell that the airboot varies. On some carbs, the bell is removeable and you can install a different one, on some it is cast into the carb and you are left to Rube Goldberg it.

Actually, I would expect it to be reasonably OK through the rpm range once it got set up, with some noticeable fall off at speed, to be sure. But the thing that I would be concerned with is the differences between the two engines they were each set up for. I'd expect to have to spend some time getting the air jet profile right on the 250F carb on the much bigger engine. Could be quite a PITA.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now