Well, I pulled the engine on the Heli. It wasn't the easiest thing to do, that's for sure. BUT i'm glad I did -> once I got the engine out I realized that what I THOUGHT was the throttle engaging was actually only the THROTTLE CABLE CONNECTOR spinning loosely around a VERY stuck throttle control rod! That would have been fun to crank up! (I would have thought I was @ 0 throttle and I actually would have been at somwhere between 25%-30% open!!!!!)

The markings on the side read "0S MAX", so I know the brand, but just not the size..... Any clues on this one? (UPDATE: I found the size stamped into the opposite side: 28 so I guess it's a 28ci)

I measured the shaft and it's 22.5mm (threaded portion) / 29mm total. I'd sure like to be able to use this engine if possible, but I can definitely appreciate the wealth of "... I didn't think of that......" scenarios!

UPDATE and Question: Here's a little something strange: The WEBRA engine I have has a "low speed needle" on the side of the muffler.... the OS MAX only has a "high speed needle"..... Am I missing something or are these OS MAX Heli engines supposed to be designed without a "low speed needle"? I guess they will run a little funny in planes.... [:-]

Any ideas or insights?