I can certainly agree and attest to the power and performance, ease of starting, and economy of the OS 75 AX. When I bought mine, I was actually looking for the new OS 55 AX, which was supposed to fly that particular plane (not pattern) very well, but the LHS didn't have one. In fact, he just sold the one he had in stock and said it would be couple weeks before I could get another. They were on back order. Demand was heavy for that engine. So, I opted for the OS 75 AX, which he DID have in stock. All I can say is WOW. What an engine.

The first start, on a brand new engine, was on the third flip of the chicken stick. I ran it as I usually do on break in, and flew it on the third tank. It performed flawlessly, as advertised, and then some. Excellent choice. And, it fits in the footprint of the OS 61 mount (and others.. Super Tigre, and so on). The .55 AX was slightly smaller, fitting in the footprint of the .46 but with considerably more power.

I have two pattern type aircraft, an Excelleron 90, and a Venus II. Both are powered by the OS 1.20 AX engine, which was what encouraged me to get the 75 AX. Those 1.20's run great. I have a third one, 1.20 AX that is, on a Goldberg Tiger 120, and it pulls that along like it was a 1.60. That's just to tell you how confident I am with the AX series of OS engines.

CGr.