I have had that same problem so I decides to break down my motor and check everthing out and just rebuild it anyhow, since it hadn't been overhauled EVER. Well , found that the dipper from the rod broke off causeing oil not to get to the cylinder, looking into it more. i fouind two tiny rolled pins in the oil pan which is what caused the dipper to break. I was lucky i decided to tear it down because i had some cylinder scaring which i honed down and check my tolerance and they were still good. i ordered a rebuild kit and fixed the govener and all it good now.