OS 62 FS problem! Plz help!
I have a new OS 62 four stroke. Ran 2 tanks for break in. Maiden flight was fine. Flew 2 flights of 10 mins. Second time out it will not run clean on full throttle. RPM drops and rises continually. Doesn't sound stable.
Things I've done:
Naturally tried richer and leaner to no avail.
Adjusted idle to run VERY well and clean with good transition. About 1/2 turn leaner than stock.
Tried different fuels.
Also tried running engine straight from fuell bottle to verify foaming or fuel line cracks/ issues. With pressure line attached also.
Also rechecked valve lash. Was a tad loose at 6-8 thousands but tightened it to 2-3 to no avail.
Also changed prop shorter 13-6 instead of 14-6. Just in case.
Removed carb and disassembled and soaked and cleaned in isopropyl alcohol.
Runs good at idle, 1/2 and (nearly) 3/4 throttle. Not full.
Now has 1 hour run time on it. Ran good for first 2 tanks
I think I've tried everything! ANY HELP here would be awesome!