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  1. L

    Notice: You can still Buy Skidoo/Rotax 277F parts New to Build an Engine.

    Would the higher thermal expansion coefficient of the 6061 billet vs the original high pressure die cast head cause problems? I would have to look but it probably expands 60 percent more per degree than a casting.
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    Anyone deviate with their engine choice?

    Where to mount it when there is no place to mount it. Anything can be done but doing anything while keeping weight down is the hard part.
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    For Sale Original bd5 650cc hirth engine

    There were problems with the 440 Hirth. The Hirth BD5 with the 440 was underpowered. I don’t know the whole story about Hirth but they supposedly shipped 500 of the engines and then went bankrupt before they could ship any more. I was told that they lost some of their snowmobile contracts but I...
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    CNC Machinist: If Machining a 2 Stroke Crank?

    In my experience the answer would be no. Even if you were able to machine it to the best of the Lathes ability you would still have to heat treat and after heat treating do a finish grind on the Id of the crank pin bore. There is a factory that has had some success in cutting out a lot of the...
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    For Sale Original bd5 650cc hirth engine

    Thanks! I agree but I have a few people that are interested in it. One just bought a bd5 and the other has one that him and his father built that has been sitting for years. So hopefully it will get a good home and go towards its intended purpose. I am selling it to help fund a new Hirth f23...
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    Competition Aircraft customer service praise!

    Let me start off by saying that I have an oddball cuyuna 215 with a belt reduction drive with oddball 4 bolt 3 1/8” center to center 3/8 hole prop flange and called around to see if there was a suitable propeller available. First I called aircraft spruce and was transferred to a tech that could...
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    For Sale Original bd5 650cc hirth engine

    From the information that I got. I have heard 55hp from some sources and 60hp from others. The hirth mechanic told me that the dual carb and dual ignition engine is a 65 hp engine derated to 60hp for aircraft use but I have read old bd5 literature that keeps referring to the "55 hp hirth". But...
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    For Sale Original bd5 650cc hirth engine

    Lol I was waiting for this comment.
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    For Sale Original bd5 650cc hirth engine

    BTW I can be reached at and the engine is located near Saginaw, MI
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    For Sale Original bd5 650cc hirth engine

    Hirth 650cc dual ignition twin carb. With original exhaust. The upgraded hirth 280r that was redesigned for the bd5 in 1973. (Hirth f20 ba1)Has only a few hours on it and was sealed up in climate controlled storage for years. Will obviously need new oil seals at minimum. Possibly more. Appears...
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