Chinese engine used as friction drive?

Discussion in 'General Questions' started by boyntonstu, Feb 23, 2015.

  1. boyntonstu

    boyntonstu Member

    Has anyone done this successfully?

  2. wheelbender6

    wheelbender6 Well-Known Member

    A friction motor should have no gear reduction. A roller around 1" diameter should be mounted directly to the engine crank shaft to provide the proper gear ratio. 2 stroke China girl motors have a built-in 4:1 gear reduction. Using cave man math, you would need a 4 inch drive roller with the 2 stroke China girl to have the same top speed.
    That is the main reason that you see goped style engines on friction drive bikes instead of China girl engines.
  3. boyntonstu

    boyntonstu Member


    Is it difficult to eliminate the 4:1 reduction?

    BTW A 4" roller is not too difficult to imagine.
  4. wheelbender6

    wheelbender6 Well-Known Member

    You can remove the drive sprocket and push the cross shaft out the clutch side. Then you would need to attach a drive roller to your engine crankset.
    Friction drive kits (like Staton-Inc, ThatsDax) will bolt right up to a Honda GX31, Tanaka, Subaru and many other engines.
    Modding a China girl for friction drive is a lot of work and probably saves no money in the long run.