Hi BAX, I will try to make this a short introduction. I bought this engine off of ebay New In Box. After running the engine for one day I knew right off the back it wasn't a new engine. Long story short I replaced the piston and cylinder and completed the running-in as per instructions. The engine ran fine for 3 solid flights, and then for some reason the engine started over heating.

This first occurred last week and today I ran the engine and the same thing occurred with the over heating. The engine over heats so bad it can't with stand a full throttle open run on the ground. The only thing that may be contributing to the heat is the MACS one piece muffler I'm using instead of the stock muffler. Please BAX give me some ideas . I checked the glow plug and it still looks new, not even burned at all. I am using a 9x6 prop and omega/power master 5% nitro fuel . The plug is an OS 8.

Thanks

RCF esq.

Few after-market exhaust systems will cause an engine to overheat. They're usually less restrictive than the stock ones. But check the size to be sure.

If you have a good piston/cylinder assembly, and the fuel system is OK, then overheating can be caused by bad bearings, something bent (like a rod or crank), or a clogged carb. The engine would need thorough checking.

I was afraid of this Bax. The guy who was selling it just didn't seem honest. So I will disassemble the engine ASAP and report back. But before I do I will fly the plane with the stock muffler. The macs pipe is designed for producing smoke and man does that sucker get hot. Thanks again.