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View Full Version : 250ex Backfiring and popping, please help!



03-05-2002, 09:32 PM
I have a 2002 250ex that has a pro circuit t-4 slip on, 108main, and 4, 1 inch air box filters.
Now, my question is:
I am getting constant backfiring and popping when I let off the throttle under load and not under load. The engine runs fine and there is no smoke.
But the backfiring cant be good on the bike.
Has anyone had this problem? What size jets do guys run with the best luck?
I would greatly appreciate any help with this problem.
Thank you.

MIKE400EX
03-05-2002, 09:36 PM
Sounds like it's lean. Just like what Raptors do when they blow their carbs off! Try richening up the idle mixture (screw).

joe250
03-06-2002, 06:12 AM
It's definately your jetting. I just put a big gun slip-on on mine, and it backfires too. gonna have to rejet

03-06-2002, 07:24 PM
What jet do you guys recommend? I have a 108 in it now. Also how many turns should I adjust the air fuel mix?
Thanks alot!