i rebuilt me freinds 400ex. went .80 over with 10:1 compression and a stage one cam and slight port job and curtis sparks exhaust. tons of power but cant keep the front end down. almost untrailble. any time you touch the throttle she stands right up even with my 240lbs a$$ over the handle bars. my buddy only weighs 180. i may try going up a tooth on the front sprocket and see what that brings.

 

you can never have too much........we have built several setups similar to that and we always want more. yes, the front end is lighter but it is faster and that is what we want. by running aftermarket shocks and tires the front end will stay down much better.

 

Even with the stock engine, the 400ex benefits from a +1 swingarm. You might try going with a +2. You should see a huge improvement. Do not go +1 though on the a-arms or it will make the front-end feel even lighter.

 

This may sound crazy but did you try less throttle?

DWT

 

my friend has the same problem, he has a 2002 400ex with 11:1 piston stage 1 hot cam, its a 416 i beleive, he is damn near 300 lbs and he cant keep the front end down, so he bought a longer swing arm and it works perfect

 

I run 16/37 with 22" Razr'2. It is a 440 stroker. It has more torque, then any other quad I have ridden.


No you didn't go too far.

 

WHERE DID YOU FIND A 16T SPROCKET. ALL I CAN SEEM TO FIND IS 15

 

I think it is labeled as a xr400 countershaft sprocket. The sprockets are the same, just have higher gear options.