I have had some problems with my motor.
The clutch seized up in "disengaged" mode, hand lever went limp.
Tore the clutch assembly apart to find nothing wrong. Engine lever had no grease from the factory and had seized from mud and water. I learned a lot about the clutch and it only took a couple hours to carefully tear into it. The special puller that came with the motor barely fit the clutch. Had to file the threads to get it to fit.
Fuel mileage is still poor. Very poor. The smallest wire I could find leans the mainjet too much so mainjet is probably OK. Still running the NT carb with the needle dropped one notch. Runs well, tan plug, now needs choke to start. Fuel mileage is in the 10L/100km range, I am looking for 3L/100km. Gasket matching, longer intake, better air filter may help?
This is my other huge "hobby", Search and Rescue.
I am over on the right. From a training exercise a few nights ago.