I have a Lawnboy Gold series 21 self propelled 21" push mower. When the mowing gets a little tough the engine becomes short on power due to low engine RPM's. Is there a way to increase the engine RPM's or advance a governer to get more engine speed and power? It only has two speeds,idle and the operating speed. Is this engine supposed to be governed to increase the RPM's when a load is detected.