Back fire

[dvx304racer]

I just perchased a hmf slip on exhasut and it back fires really loud when i let off the gas what should i do????

[knoxville9]

Rejet our carb

[dvx304racer]

ya i know it needs to be jetted its just i don't know how is there a site that tells you what to do and where everything is located like the pilot and the main and the air screw im new at this

[twincat800]

if you just put a slip on on it. I dont know too much but i would try a 25 pilot. the stock main is something like 130 or 135?? and with a slip on AND an air filter i would say try a 155 main. BUTTTT if you dont have an air filter on it i would guess trying a 145 main, that would be a start i guess. To do this stuff loosen the carb and unscrew the 4 scres at the botton of the carb. When u buy your new jets you will be able to tell which one is which. The main should have a plastic or metal bowl on it that should slide right off. They both use a flat head screw drivier to take out, its not hard at alll.

[twincat800]

With the new jet in there, put a new plug in and run it hard through all of the gears, shut it off, then coast to a stop. The plug should be like a light brown. If its white the u need a bigger main jet, if its dark, u need a smaller main jet.