Jetting/fuel delivery issues???

1 reply to this topic
  • 2in2out

Posted January 21, 2011 - 09:53 AM


I've done my searching and have come up with no solutions.

I have a jetting issue I need help with.

Ride altitude 3000-9000 ft, Temp 40-100F, RH 3-35%.

The 06 I had last year had grey wire, air box, AIS Blocked, JD jetted for 3000-9000ft 168MJ, 48PJ, Red @4, FMF PB header, FMF 4.1 can. Ran bitchin'!!!

My newer 07 was running ok with grey wire and airbox done, jetted for 6000-9000 165MJ 45PJ, stock exhaust(I bought it in Ut, El. 6000ft). I put in a PMB insert, JD jetted for 3000-6000ft 168MJ, 45PJ, Red @4, ZipTy fuel screw. Bike became hard to start and I hadn't had time to get things really adjusted well.

Yesterday, I put on the FMF MB and Q4 i just got, and 165MJ, 48PJ, Red @4. Temps in the 50's. No start. No fire at all. Got dark, and had to do dad stuff, so I didn't check plug and spark yet.


Edited by 2in2out, January 21, 2011 - 01:09 PM.

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  • William1

Posted January 21, 2011 - 10:20 AM


A few things. Not that it matters at the moment, but a 168 at that elevation on a 450 is kind of big. I'd think you'd be better with a smaller main. Once we get your idle sorted, try a smaller, like a 160 main.

Now, regarding the starting. The basics - Only the pilot and (if used) choke/starter jet come into play.
New Fuel?
New (not just clean) pilot jet?
Again, at your altitude, I'd expect to see a smaller pilot esp with a zipty alloy fuel screw (they are notorious for needing significantly smaller pilots). If you have a 42 pilot that is in like new condition, try it for starters.

Once you get it running, do this (from the sticky at the top of the forum):Selecting the correct Pilot Jet and setting the Fuel Screw


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