backfiring

[ExCraver]

I have a 1990 honda 250x with a supertrapp full exhaust system. I jetted it and put a clamp on K&N filter on it. It back fires from the secong i hit the throtlle to when i let off. I think i have the jetting off but could use some ideas

[m250r]

definitely sounds like ur jetting..just give that a check

[tanner24]

yep, you are too rich.

[cals400ex]

what is the stock jetting (mainjet, pilot jet, and needle clip position)?