The manual tells me to check valve clearances every 25 hours. I have been checking at each oil change but today, first hot day and initial takeoff rpm good but once engine warmed up was not developing the power it should.. indication was throttle way forward to get cruising rpm and max rpm only about 2100. Went back and landed with no compression. Last time same thing but compression came back when engine cooled. I need to let it cool overnite and readjust valve clearances. Factory setting 0.20mm after i talked with then they suggest change to 0.35mm. I did and it is working well.