I have a 87 sammy carbed all stock. i got it for 200$ and it was sitting in the woods. i have put new air filter new fuel filter new plugs new plug wires ran ok for a while never could break 50mph. I have been tooling around in it on our property and having a blast. my problem started when i took it out one night and got it to about 35 on our road and it cut out on me took it home finally checked the plugs and they were fouled so i replaced them and it started right up. took it out for a ride drove less than a mile down he road and it cut out on me again fouled the plugs again. any ideas or any help has anyone else had this problem. im hoping head gasket or valve guides leaking oil but im scared its piston rings? any other ideas and has anyone done a basic rebuild on these how much and where to get rebuild kits if neccessary?