Help with JD kit on my WR450.

5 replies to this topic
  • mjb40

Posted February 26, 2004 - 04:58 PM


I installed a JD kit on my '04 WR450 this week. Standard settings with PMB insert, and open airbox. At 1 3/4 turns on the pilot screw I was getting some popping and backfires on deceleration, and stuttering up to 1/2 throttle, then hang-on! At 2 1/4 turns the popping improved, but I still have the stutter in the bottom 1/2. At 3 turns it got worse again.
I'm riding at 1200ft and 40 to 50 degrees. Whats my next move to smooth out the bottom half? Will a move up on the jet needle solve the problem, or should I try a #48 pilot jet? Any advice would be appreciated.

  • basicblues

Posted February 26, 2004 - 05:06 PM


Which needle are you using? Red or Blue?

  • mjb40

Posted February 26, 2004 - 05:27 PM


I'm using the blue needle in the 4th clip position, a #170 main, and the stock #45 pilot jet.

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  • Indy_WR450

Posted February 26, 2004 - 05:34 PM


Try the 165 main, red needle #5, 48 pilot, 2 turns out. I think you are running on the rich side at the needle and lean on the pilot. Cutting out is a sign of rich condition. The jetting you are using is what I use at 30 degrees and 700 feet with an uncorked stock pipe. :)

  • mjb40

Posted February 26, 2004 - 05:48 PM


I ordered a #48 pilot jet and should have it in a couple of days.
Wouldn't a rich needle and lean pilot balance each other out? :) Probably a stupid question, I'm a slow learner, but I can be taught.

  • YamahaSteve

Posted February 26, 2004 - 06:27 PM


You probably do not want do that.

Size each circuit's jets appropriately for the conditions. With a little patience you can get all the circuits jetted right without having to use the pilot circuit to compensate for the needle circuit. That is just my $0.02.

I would agree that it sounds like you are rich on the needle.


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