Jetting prob due to TPS setting

Still looking for 'THE' ideal jetting, somebody told me to check the Throttle Position Sensor before going any further.

(main 175, pilot 45, clip #3)

The problem is that the bike rides great but is fouling plug after plug (plug is soot-black after riding).

Does somebody has any experience with this ?

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'99 WR400 F, YZ exhaust, throttle stop trimmed, WR timing, airbox cover removed

I had the same problem.

change the needle to a dvp PT# 5be-14916-dp

clip#3 ,and change the main to a 180.pilot 45

Thats what I did and my bike runs like a bat out of hell. :)

98wr400f stock exhaust,throttle stop trimmed yz timing, airbox cover removed,fmf hi flow head pipe,

also do a search on this issue and you will get a ton of info.

The problem is that your jetting is adapted to a YZ timing. Bigger main jet and DVP needle (same taper as DTM but bigger diameter = leaner)

Thanks anyway. :)

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'99 WR400 F, YZ exhaust, throttle stop trimmed, WR timing, airbox cover removed

Ynahg,

What is your pilot screw setting at? Have you tried turning it in? This is most likely the problem.

The DVP bill suggested is a bigger diameter and is a sensible choice. It's not even close to how lean the newer '00 & '01 WR's diameters are (DRS and DRR).

Last letter sequence rich to lean is- M,N,P,Q,R,S

DVP#4 is a good starting point for a D-- needle regardless of cam timing.

James

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