Help In Texas

Hey Guys I really need help. I have a 1998 WR400F thumper that has a rich fuel condition from part throttle to wide open. The bike cranks and idles very good. As the engine warms us it starts to run rich at part throttle. I have overhauled the carburetor and checked and rechecked every circuit. I have a manual. I have tested every electrical circuit and every electrical part.

I have even cut the gray and the blue wire on the cdi unit. It did not make a difference. I have replaced the cdi unit still no change. I have changed the needle jet to the leaness setting. I have also changed main jet from 168 to 150. Plug was leaner but condition was still the same. Also I have checked

valve adjustment and for vaccum leaks and everything was good. I would appeciate any help. Bob

Have you done the mod to the accelerator pump, so it doesnt shoot too long. BK mod I think it was called. My YZ was used to flame out due to too much acc pump.


No I haven't. What is a BK mod? Thanks, John


1998 wr400 runs wif the first generation of fcr.. u cannot do a bk mod on those carb..u mite wanna do a search on taffy mod for those carb..cheers

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