Hows everyone doing ? Im new to this forum , so ill give you a little info about myself then move onto my question . My name is Kris im 30 years old , i live in Dutchess county NY .In my toy garage i have 05 Suzuki Z 400 , 07 Honda 250EX , 91 Yamaha YFM100 , & 2 Kazuma 90cc Mini Falcon's . So on to the question : I put a new slip on muffler on my girls 250ex now on decel it starts popping/backfireing any quick fix's besides paying to rejet ? Thank you

 

First make sure you have no air leaks from the head to the end of the pipe. If you have a leak it will suck O2 and that will mix with the left over gas in the pipe and give you a pop.

If you have no leaks then open up the fuel/air screw on the carb a half a turn at a time until the pop goes away. If this does not cure it you will have to jet up a tiny bit.

 

thank you for the info , i do believe i have a slight leak in between the front pipe & the slip on , ill have to look into sealing this up better . thanks again

 

You may be running lean. That's bad and can cause piston meltdown. Bigger jet.

 

so best bet would be to pay to have rejetted i quess

 

Pay??? No way. It's cheap and easy. Buy 4 or 5 in different sizes (a few bucks each) and try them one size up each time.

 

thank you for the info