Hello so I have a taotao 150 powermax. It ran great tell my exhaust broke off. I drove it maybe less than 25 miles without my exhaust trying to get it home and than like two other times due to emergency situations. Than i parked it since winter came for like 8 months. So now i bought a new exhaust and got it running and replaced my spark plug, oils, and fuel filter. But now it backfires when i slow down unless i feather the gas. Ive tried adjusting valves. I was told its running lean well i pulled my plug that is new and its black so that means it's running rich right? I did a valve adjustment and that helped alot but still backfires. I have a feeling ive burnt my exhuast valve out but what is your guys opinion and what should I start with?
Also im running a "performace" CDI and coil. I was also told that it could be that too.