Pilot Jet question.

3 replies to this topic
  • asg5265

Posted November 29, 2011 - 02:25 PM


Alright guys, I have checked the jetting database, have a JD jetting kit, and heres the story. When I was back home for TG, I decided to ride the 06 450, long story short had wrong pilot (45 instead of 48) so I put the 48 in when I got home. This is after i lost the fuel screw to the desert, and had to quit the ride.
Anyway, so I have the FS out 2.5 turns and a 48 PJ installed and we still get pops and back fires and little nagging stuff like that. I figured because the weather was cold that day, it was very dense, that it could use a 50, anybody else have to do this in the winter?
We run twin air filters and a full two bro exhaust and a freshly redone head with all new valves etc...
It was really backfiring bad and wouldnt idle then would hang idle. fixed mostly with the 48 and fuel screw out a ways, but should I go to the 50 because its still not really right? relatively speaking just for the winter months?
never before have we rejetted for exhaust or anything so this is news to me...

  • grayracer513

Posted November 29, 2011 - 02:36 PM


Double check that the popping is not due to an air leak in the exhaust system forward of the muffler. Also check things like the air boot and the hot start plunger to ensure they close and seal.

A #48 pilot seems large to me, especially at altitude, and a 50 seems way big. What kind of fuel screw did you replace with, and are you sure the spring, washer, and O-ring are in place on it?

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  • asg5265

Posted November 29, 2011 - 03:39 PM


fuel screw was installed with all 4 parts. I mean I ride at 2000 feet. thats not too high. we have yet to rewrap the header to muffler section but we did that once and it still does popping. so idk Im thinking with the exhaust we have to go big or go home

  • albertaborn

Posted December 06, 2011 - 07:11 PM


ive got a 04 yz 450 basically stock other than power bomb fmf full exhaust and quick shot 2. im big into winter riding up in alberta at 2800 ft and so far have been running 45 PJ 175 main 3rd clip. this bike is new to me im used to my cr500 but this thing is hard to start so was thinking going up a size on Pj and it does pop on decel and seems to cut out slighty at full throttle so might be bit lean. any ideas

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