Neighbor Proffessor has problem with Craftsman rider. 15.5 Briggs vertical shaft

Mt neighbor, Math Professor, has a Craftsman rider with Briggs 15.5 HP vertical shaft engine. I will hear him mowing and the mower runs great until it gets warm/hot and suddenly quits. Let it sit for for awhile and uses his push mower. Rider will start again after about 30 minutes. Runs fine for awhile and then quits.

I try helping him at times, plug is fine, gas fresh and clean. I have adjusted the carb for him. Anyone have a suggestion. The neighbor is a Doctor of Math here at Tarleton State University in Stephenville TX. Trying to help him out.

Any suggestion will be appreciated.



Thanks in advance

Rec Cox