I have a 1980 Brat with original motor and carb. It seems that it if is hot outside or I run it for an extended period that it gets hot and will die. Sometimes it will idle fine but as soon as I turn it off its hard to start. I can restart it but it takes a minute. Sometimes it won't stay running until it cools down. I tried having the carb rebuilt but it didn't help. Any help or experience would be great. Thanks!

sounds like it needs to be tuned or possibly a timing issue.

Poor ignition components. Coil, module, plugs, wires, cap, rotor. Test - then replace.

 

GD