I'm thinking about getting a used 400EX but, I had a few questions first. I know they are rock solid but, I have seen 3 of them need their heads replaced. Is this a known problem with the head itself or is it related to running K&N filters(not keeping them clean)? I was also told it could be due to weak stock valve springs? It's weird because in almost all cases the piston/bore was fine and the motor ran perfect with the new head. I'm really looking forward to getting my own. The only motor related mods I would be doing is a pipe, UNI foam filter, and jetting to match.

 

No one at all?

 

I got my 99 in jan 1999 it has been industructible i had to put a clutch and axle bearings in. some other bent parts from crashing. it is tied now but that is to be expected.

 

i have never had any problums with my 04 and i have a big list of mods if you are looking in to a used one i am seling mine private message me your e mail and i will give you more info if your interested

 

I got my 99 in jan 1999 it has been industructible i had to put a clutch and axle bearings in. some other bent parts from crashing. it is tired now but that is to be expected.