Jetting prob due to TPS setting

3 replies to this topic
  • Ynahg

Posted April 12, 2001 - 03:47 AM


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 ?

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

  • Guest_Guest_*

Posted April 12, 2001 - 04:24 AM


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.

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  • Ynahg

Posted April 12, 2001 - 05:14 AM


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. :)

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

  • James_Dean

Posted April 12, 2001 - 07:10 AM



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.



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