[Rich Biebel]

A very common problem on small air cooled engines with solid lifters. They run fine cold but start running bad and stall and won’t restart. Not enough valve lash on the exhaust side. It quickly gets worse when the valve is not able to touch the seat and shed some heat. Onan old style flathead opposite opposed twins did it all the time. Lash spec was .013” on exhaust side. Valve face wears and lash gets tighter. Eventually the hot engine runs bad/no restart scenario. Drives you crazy until you figure it out! One of many odd scenarios heat related I’ve dealt with.