Quote: Originally Posted by Fedor
Ive read a couple things that maybe wrong.I first checked the carburetor and It was fine. The other things it could be is the spark plug ,timing chain or the valves. The valves make me a little nervous but apparently what Ive read its an easy fix. I'm just trying to get other input before I doing something else.
I had the same problem with my 2003 KFX 400, I did all the same things as you checking and cleaning the carb, I then took the head cover off of my wheeler... To measure the valves, I figured out that it was the intake valves, They were cupped and That is probably the same problem with yours I had backfiring and a load of other stuff, My advice is to go with the Ferra stainless steel valves (High Performance and stronger) And also take it to the local dealer that will save you a pantload of time and keep you from going insane. GOOD LUCK