1987 yamaha moto 4 spark issues

[sledfreak440]

Hi I have an issue with my moto 4 involving the spark. I thought it was the coil so i replaced it and put a yamaha factory one and it started right up and ran for 2 -3 seconds then suddenly stopped. I bought a ebay one for 15 bucks to see if it was my coil again, installed it and then started it up and did the exact same thing. I did change my spark plug every time, i tried by passing the kill switch wires and it still just keeps on cranking over but doesn't wanna start. My battery also doesn't keep the charge, as soon as i take off the battery charger it doesn't have any juice anymore. Could my battery be grounded out and keeps screwing up my coil? I was told one of the grounds might be bad, so I looked and they seemed to be all good. Any one have this issue before? Thanks again for your time.

 

[maim]

that atv should run without a battery in it but a new one would not hurt. try a set of booster cables from the coil to the engine to confirm the ground problem.