Overheating why? can only run four an hour at most

Either the gas mixture is not quite right or the gas cap is slightly clogged.

If you don't have enough oil in the gas, this may cause it to overheat.

The next time you run the chainsaw and it starts to die, loosen the gas cap. If it starts running again, then you know that it's a clogged gas cap.

You may also check the air breather, it may be dirty as well.

If you need further assistance, just let me know.

Jim