Predator 500 seems to be firing early and will not start and stay running. HELP!

Bought an 03 Predator and was told it needed a new timing chain and that the float in the carb was sticking. I checked the valve timing and they were both off about 4-5 teeth equally. I replaced the timing chaing and shimmed the valves to 5-6 thousandths on the intake and about 9 on the exhaust. When the T was lined up the engine was at top dead center. I rebuilt the carb float valve looked to be fine but I replaced it anyway.

I tried starting quad last night and it did start for a second and was running fine for about 10 sec then died. I tried starting again but the battery was dieing. I hooked up my jumper battery which is just a 12v battery out of a wheelchair that I used for jump starting quads that I am working on when the battery is junk or dead. It turned over and fired but sounded like it fired early big a loud clunk. I turned it over again and it turned and turned and then another loud clunk. Too afraid to try again. I am thinking it might be the CDI. It has a big gun rev box. Could it be the coil? Anyone have any ideas???