I don't know the greatest amount of information about the mechanics and things of atvs. I just put a White Brother's Pipe on my 300ex, and in the higher gears when I let off the gas to down shift it backfires a bit..I haven't ran it too much with the pipe, and I rejetted from the stock 122 to 130 (what the area dealer told me to do). Is the backfiring of the exhaust normal? Let me know please thanks.

 

The main jetting is fine with a 130. You need to richen the idle circuit with a bigger pilot jet. I believe stock is 38 and you need a 40. Richening the air screw might be enough, but most likely you will need the bigger pilot jet.

 

What's up with the backfiring though? Would that cause it, or is it a normal thing???

 

When the throttle is closed in no matter what gear, it will draw fuel from the idle circuit. When rich enough on the idle circuit the unburned gasses in the pipe will not ignite. When lean enough it will, causing a backfire. The same will occor if there is an air leak on the exhaust between the cylinder head and exhaust header pipe, or between the pipe and muffler.

----- Gregg -----

 

Will it be fine if I ride it like that, or at least for a weekend? I'm going up Memorial Day weekend for a big weekend of riding and I don't think I have time to look into all of that...

 

It is simple there is an adjuster screw on the bottom of the carb and try adjusting that to see if you can fix the problem, turn it about a 1/4 each time and hit the gas until you are just about perfect, but I would also try and get a new pilot if this doesn't help.

 

So did you get your backfiring fixed? Was it a simple ajustment of the airscrew?

 

yeah i have a ozark 250 and every time i let off the gas when its cool it backfires on me like a bitch