I've had a few OS engines in my short time in the hobby. 5yrs. worth.

Yup- the 61FX is overweight and underpowered when compared to other engines in the same class. I've had one for about 3yrs. now and it's never showed any signs of peeling. (fingers crossed) It starts and runs, but don't expect ballsitic performaqnce out of it.

My 46FX was worn out in a year. It never peeled, but it wouldn't turn a 10-6 over 9800RPM after a yr/. It was given to me by a friend, and I suspect he broke it in too rich for too long-- ruined it before it ever had a chance. I replaced the cylinder/piston assembly with heli parts. The 46-Heli engine is identical internally. But, it's got a ringed piston/liner assembly. The heli cylinder IS nickle plated. After slapping the heli parts in the FX case-- I've got myself a screamer. It has a full tuned pipe now and it absolutely RIPPS!!

My OS 120 Surpass (non-pumped version) was a big POS right outta the box. I fought with it for over 2 years before I took a 16lb. sledgehammer to it after yet another a day of frustrating problems with it at the field. I had every "engine expert" at the field and every hobby shop in town messing with this engine and it just was a POS. NOONE could get it to run right. I replaced O-rings, needles, valves, carb, gaskets, bearings.etc. I tried new fuel, I tried old fuel, new plugs, old plugs, adjusted the valves probably 2000 times. Just about spent $500 on new parts to rebuild a NEW $350 engine. I cannot describe the feeling of pure unadulterated joy and extasy when I took that first swing with my 16lb. sledgehammer. I smashed it into kibbles and bits for about 20 minutes. Nothing left of it but a pulverized mess of aluminum when I got done with it.[:@] Threw the scrap in the trash can and never looked back.

Would I buy another OS engine-- probably not.

The Tower Hobbies .75 is a GREAT engine IMO. I've got one in a Chief Giles 3D fun fly plane. I broke it in with 10% fuel and 22% oil. A special blend of 75% synthetic and 25% castor with a total oil of 22%. I just switched to Omega (pink stuff-castor) 25% today. This engine tunes easily and holds a needle setting consistantly. It idles very well and transition is fantastic. For $100, you can't beat it. My Chief Giles 3D weighs 5lbs. 8oz. and it hovers at 1/2 throttle with the TH .75 I plan to buy another one for my next 46 size fun fly plane.

If you don't mind the added expense of a new card-- a ST engine is a good runner IMO. I've run a few ST3000 and ST2500 engines. Only thing that needs fixin' is to get a new Perry carb for it. They are ringed engines and they take a lot of fuel to break in, but they put out gobbs of power on low nitro fuel and they last forever.

I'm looking at all kinds of engines with good reputations now. My money goes where others have had good luck and quality.