since I installed a full exhaust. my baja backfires one time about 3 seconds after I shut it off like clock work. I have installed jets from .190 down to .175 turned mix from 2 to 3 turns out. right now it has .175 main and 3 turns out on idle jet. it is running really good with that setup. but still continues to backfire after shutdown. any sugestions? I don't think I have a exhaust leak. if It did, how can you tell? I am about to put my stock exhaust back on if I can not figure this thing out.

 

I had a similar problem on mine. My exhaust pipe had worked its way loose from the motor. Retighten the bolts.

Could also be the jetting. Maybe someone can help you with the jetting. Seems like your running a high jet. Im running a 165 main with the needle clip in the 5th position. And 4 turns on the air screw.