i ride a 250ex with a pro circuit t4 full exhaust. every once in awhile it will back fire, its not very loud but it is noticeble. if i put a kn jet kit and a 105 main jet will it fix this prob? if not what will?




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01 250ex
DG alloy bumper
DG alloy nerfs(reinforced)
Pro circuit full system
K&N air filter with outerwear, air box lid removed
razr rear tires

 

I ride a 250ex and I put on a pc t4 full exhaust also. I have a k&n filter and an outerwear on the filter. I ride on the trails in the national forest in upper michigan so I put the quit core insert on the t-4. Pro circuit told me I just needed to up 1 on the main jet, which is a 98. it runs good but it still was backfiring when i let off on the gas. my dad increased the idle mixture screw a 1/4 of a turn until the backfiring stoped. It was a total of a 1/2 a turn out. In the april 2002 issue of dirt wheels there is a good article on jet setting. that is where we found out about the idle screw adjusting.


2003 250ex
K&N air filter
outerwear
Pro Circuit T-4 Full System
Trail tech speedo
DG nerfs
Homemade skid plates and a-arm plates