i was out tonight in the dark and saw blue flames 8" long blowing out of my pipe (holy ****) i thought, i am running a HMF 142 main, 1 3/4 on the air, why is this thing back fireing , it never used to, does it need new packing, mabey i should go pick up a dyno jet kit?

 

If its backfiring on let off, the idle circuit is lean. Either a vacumn leak, or your mixture screw needs to be richer. Try 1/4 turn, and if thats not enough, go more. If you get to 3 turns out, and you still have problems, go to next up pilot jet.

 

thanks