Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Do you have a compression gage to test the compression? If compression is above 100 psi, the compression release is not working It is a spring loaded weight on the back side of the camshaft gear.
Sounds like this camshaft was replaced under the warranty.
You can try to adjust the valves, setting them to the close side, around ,004 inch. If adjusting the valves does not help , the camshaft compression release is likely problem, and the only solution is to replace the camshaft again!