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Thread: Dirt bike engine for ultralight?

  1. #1

    Dirt bike engine for ultralight?

    I have a 2001 KTM 125 SX engine just sitting in my shop. They put out hp in the mid 30ís and are super light. Would adapting it using a chain drive or belt drive be recommended for an ultralight application?

  2. #2
    Dana's Avatar
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    I converted a Kawasaki KX100 engine for paramotor use. I kept the gearbox but removed the gearing except for the 3.4:1 first stage which normally drives the clutch, with the prop shaft and support bearings mounting where the clutch cover used to be.

  3. #3
    Cool. I want it to go in an affordaplane or a minimax. It can be upgraded to a 200cc easily also. I raced KTM’s for years so I know they are tough engines. I’m just brainstorming and trying to get airborn on a budget. I’m a former F-15E mechanic as well so I’m not clueless concerning aircraft.

  4. #4
    Sam Buchanan's Avatar
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    Quote Originally Posted by Backwoods Smith View Post
    Cool. I want it to go in an affordaplane or a minimax. It can be upgraded to a 200cc easily also. I raced KTM’s for years so I know they are tough engines. I’m just brainstorming and trying to get airborn on a budget. I’m a former F-15E mechanic as well so I’m not clueless concerning aircraft.
    Two suggestions:

    1) Forget the AffordaPlane, too heavy. The MiniMax is a far superior aircraft and can be built as a legal ultralight.

    2) Your inquiry would probably be better served in the Ultralight sub-forum.

    Best wishes for a successful project!
    Sam Buchanan
    EAA Technical Counselor
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  5. #5
    Dana's Avatar
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    One issue with dirt bike engines is the narrow powerband, all the torque is at the top and. On my paramotor it was a fine line between enough prop pitch to hold the rpm down at full throttle vs. too much pitch so it never got "on the pipe".

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