Motor shuts down after it warms up

[Dansweeney]

I just purchased a 1981 XS from a friend that says the motor shuts down after it's been running for short time. He said that he had put a second coil on it but the problem still exist. Can anyone give me advise as to what could be the problem. I know it sounds like the coil and it's possible that both coils are bad but besides that could it have other problems? Just brought it home tonight. Couldn't turn this one down. Title and a motor that runs for 10 min. at a price of $500.

 

[deadchef]

battery might not be charging. put a volt meter on it and rev the engine. the voltage readings should be in the 14v range i do believe.

 

[Dansweeney]

I was told that he had done that already but I can double check

 

[deadchef]

never, ever, ever ever ever, trust a po. always check.