gy6 150cc with performance exhaust back fires

[tkrocks2]

I have just got my first gy6 150cc scooter I have had many scooters in the past but this is my first chinese scooter.

When I bought the bike it had a cadillac converter in the exhaust so I removed the stock exhaust and put a free flowing performance exhaust on it along with a perfermance cdi box and coil.

The engine back fires sometimes when I let off the throttle a friend of mine told me it sounds like it is sucking in air form some where.

I removed the exhaust and where the exhaust bolts to the cylinder head used some exhaust sealent I'm waiting to see if that fixes the problem.

I'm not sure what else I can do if that is not the problem.

[tvnacman]

the acv on the carb richens the mix on decel. Have you done any other mods?

John

[dwint51]

have you changed the main jet

[tkrocks2]

no other mods besides the exhaust I plan on doing some transmission mods but right now it is the exhaust then go from there I have not changed the main jet yet.

I know main jets are different from place to place so are there any main jet kits for these bikes?

[dwint51]

I get all my stuff from scrappy dog scooters.good people over there

[tvnacman]

check the acv.

John

[tkrocks2]

I made a baffle that I put between where the header pipe and the muffler join witch seems to be working perfect and I have got more power on take off.

I have a new problem now my battery went dead on me a couple times so I charged the battery and put my volt meter on it and it is not always charging at 13volts it will drop down to 8 volts or lower then back to 13volts what can cause this to happen?

[tvnacman]

what is happening when it drops to 8volts?

John