Jd jetting issue. Insight appreciated.

2 replies to this topic
  • bultaco

Posted September 20, 2009 - 03:10 PM


Have a 99 WR400. JD jetting installed for sea level to 4,000 ft. Live in coastal California. Also installed all new jets, AP unit with longer prong...thus shorter squirt. JD call for air box cover removed, grey wire cut, aftermarket exhaust...all which is complete on my bike.

Stock settings: My settings:

Main jet 168 170 (per JD instructions)
Pilot jet 45 48 (JD suggests stock?)
Needle jet standard standard
Pilot screw standard external aftermarket
Starter jet 60 60
Main air jet 200 200
Pilot air jet 1 75 75
Pilot air jet 2 90 90
Needle pos. 3rd (OBDTM) 3rd/blue needle

Prior to JD installation: 4th clip and 168 mail...hesitation in 5th at WOT.

Thus, the only deviation is that I have a 48 main vs 45 suggested. Would this difference cause a "gargling" in various gears as well as deceleration popping which did NOT exist prior to JD jet installation? I checked the plug and it was not white but dark brown color, moist thin filmed and not crusty dark coated. HOT Cams exhaust cam installed for easier starting, clearances checked 3x for certainty. I will check for head pipe tightness to eliminate from popping probability.

Any insight appreciated. Joe

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  • Krannie McKranface

Posted September 20, 2009 - 05:06 PM


You probably induced an air leak somewhere. Take some carb cleaner and spray it on and around the carb while it's running.

  • Birdy426

Posted September 20, 2009 - 10:08 PM


Also be aware that gurgling (at least what I call gurgling) indicates too rich. Popping out the exhaust can come from either a too rich condition or a too lean condition. May want to try the red needle, or raise the clip onthe blue needle a notch...


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