I purchased my 701 with a 670 rotax (built by rotax rick) already in it.
Things I like about the 670
Great power to weight ratio (92hp @ 100lbs)
Simple engine, less to go wrong, small size leaves plenty of room to work on it.
Initial cost and rebuilding is much cheaper than aviation engines.
Things I dont like
2 cycles have reputation for stopping suddenly with little or no warning. So far (120hrs) this has not been my experience, but something I think about and try to keep in mind.
Recommended TBO is less than other aviation motors, although still cheaper in the long run.
Have to add 2 cycle oil, on longer trips, you need to have it along with you.
You have to watch EGT very close, easy to get lean when descending (this is something I have gotten used to, not as much a problem if you are careful. )
The weedeater sound....very LOUD weedeater sound.
Also higher fuel consumption than 4 cycle.
Overall I would recommend the 670 rotax for the 701,
I do think it requires being more careful in operation, but a good choice.
If I were to have my choice in currently available engines, I think I would probably prefer a Viking, nearly the same price and 4 cycle, much quieter, parts easier and cheaper to find, much better fuel economy and still good power to weight ratio.
Hi, Micheal. I finished my 701 in 1997 and flew it for several years. One day a guy came by the hanger and offered me a very good price so I sold it. The only reason I sold it was it had a 2 stroke 2 cylinder Rotax and at the time I couldn’t afford a 912. I have since rebuilt a 701 that had a hard landing and helped finish another 701 when the builder became too sick to finish it. Then got very busy working on airplanes doing repair and annuals. I have finished rebuilding a 415C Ercoupe that is ready to fly now. Will be flying it to Kingsley for breakfast this summer and would enjoy seeing your 701 sometime.
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