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!

Are you using an OSF plug? If so try a new one.

Dennis

Yes. And I have a new OS type F plug. Will try that. Brand new engine.

Tried new glow plug to no avail. :(

Problem solved! LS needle was effecting the HS. Richened LS and HS came right in with no surging!

Once you get it right where you want it gently turn in the high and low speed needles counting the turns until they stop. Write the turns down in your manual and you will always have a baseline to return to if things get out of wack again.

Dennis

Good advice Dennis. I'm flying tomorrow and will wait until after the flight to record. Things sometimes change in flight vs. static. Thank you.