I think there is plenty of blame to go around. All these small air cooled gas engines are built to CARB standards, even those sold in non-CARB states. They simply run too hot, especially if there is any amount of obstruction to the air cooling.
Power Tracs by their nature are sometimes operated in dirty environments, and by their design make it difficult to keep the engine cooling fins and blower housing clean. You simply can't get to the engine very well to blow out all the passages.
The engine manufacturers don't help. Kohler, for example, says to remove the blower shroud at the 100 hour service interval and thoroughly clean the engine. That would require removing the engine in my PT-425. The manufacturers should make easy cleaning of the engine a design priority, but they don't.
Lastly, there is the non-instrumentation of these engines. In my opinion, they need cylinder head temperature gauges. If the engine manufacturers don't offer them, Power Trac really should do so. If nothing else, they could make them optional. That way if something clogs a passage where it can't be seen, the owner could be warned about it by the abnormally high head temperature and take action before the machine is knocked out of service and requires expensive repairs.
