Jetting feedback

3 replies to this topic
  • drtbk4ever

Posted June 30, 2006 - 09:53 AM


Hi gang, I have been doing a lot of reading on jetting and I think I have the hang of it, I just need confirmation that I am on the right track.

I have an 04wr450, Canadian model, so already has yz throttle stop and no grey wire to worry about. No other mods and stock pipe (I know I know, toss the insert. but I need it quiet).

Here is what it has.
main - 160
Needle - OBDUQ - 4th position
Pilot - 48
Leak - 50

I ride at 2000 feet in temperatures between 60 and 85

The bike outright rips when I crack it wide open so no issue there. But it still pops on deceleration so that means it is lean, correct? Indy's jetting specs suggest between a 165 and a 168 main for my elevation (but I am running stock exhaust) so I thought I would go up to a 165.

I have no clue what to do with the needle as Indy is using the JD kit, but am I close with the OBDUQ on 4th position?

Pilot is a 48 already so I won't change that. But while cruising on low throttle (1/8 to 1/4) the bike has a major hesitation, sometimes enough to jerk you around a bit. Could that mean my Pilot jet is clogged?

Lastly, the leak jet. I think I am between a 40 and a 50 according to Indy's specs. Would dropping it down to a 40 give me a little more torque off the bottom?

Thanks for the input guys, I can't tell you how much I have learned from reading your posts.


  • WGP

Posted June 30, 2006 - 10:13 AM


I'm no jetting expert......but it sounds like your on the right track...I would start with a 40 leak, that little jet made a BIG difference, it cleaned up the lower throttle alot. If that doesn't help, play around with the pilot, if popping on decel(too Lean!!) move a size or 2 richer on the pilot. Lastly, If you can get the JD needle, its tapered for a great running bike.

Good Luck!

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • MotoGoalie

Posted June 30, 2006 - 10:15 AM


Decelleration popping can be rich or lean jetting.

Does you bike smell like unburnt fuel?

Does it get harder to start when hot?

Your PJ might be a tad rich. Try leaner, maybe 45.

And always remember, Only change ONE thing at a time.

  • drtbk4ever

Posted July 04, 2006 - 08:01 AM


Hey Guys thanks for the info.

Good point about only changing one thing at a time.

MotoGoalie, the exhaust has never smelled like unburnt fuel and the bike starts easily when hot. I have never needed the hot start lever. All I need to do is press the starter and give the throttle the tinyest twist.

So is popping on decel usually a pilot issue or a main issue?



Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.