It's a Huasheng 50 cc 4 stroke that is a Honda GXH 50 clone.Hi
Run times are as long as you are moving the engine will not over heat , it's only if it's not run in or going slow or at idle for long times , as for cool down as long as you can put your hand on the engine like the barrel or head it is more than cool down to ride .
Happy Cruising.
Laza
OK
That's one way at looking at it but you should never let an engine idle with out a load for more than a few minutes at any one time as it will glaze the bore and cause underdrew wear in the engine which will lead to overheating and a ceased engine.
So this is why you should threat it like a air cooled engine as it is to get the most life out of your engine , fan or no fan .