Build up a 48cc to a 60cc?

Discussion in '2-Stroke Engines' started by mikesbike, Aug 17, 2010.

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  1. mikesbike

    mikesbike Guest

    Can a 48cc motor be converted to a 60cc by just changing the top end components? Cylinder, piston, head, etc.

  2. motorpsycho

    motorpsycho Active Member

    I think the stroke may be different, possibly a different crankshaft, or a shorter/longer connecting rod.
    in my opinion, the cost and all the trouble doing it would not justify the effort.
    48 cc.'s and 66 c.c. make about the same power and you probably wouldn't even notice any difference. have a 48 c.c. that will walk away from my friends 80 c.c. any day of the week. same style bikes, same size sprockets, same basic set up between the 2 bikes except i have an exp. chamber, and he weighs about 50 lbs more than me.
    even if we switch bikes, my bike will still walk away from his.
  3. AussieSteve

    AussieSteve Active Member

    At least in the case of the ZBox engines, the stroke is the same on both 48cc and 66cc.
    From the ZBox site:-

    48cc - 40mm bore x 38mm stroke.
    66cc - 47mm bore x 38mm stroke.

    I've always been under the impression that the bottom-ends were the same and that the only difference was in the bore.

    N.B. motorpsycho, a longer/shorter rod won't change the stroke.

    According to ZBox again, there's a considerable power difference - 1.2kW for a 48cc and 1.7kW for a 66cc.
    In my opinion it could well be worth the effort.
    Last edited: Aug 17, 2010
  4. GearNut

    GearNut Active Member

    From what I have learned reading the forums, there are different bore sizes, rod lengths and piston heights as measured from the centerline of the wrist pin to the piston crown.
    The variances are due to the different manufacturers that make these kits.
  5. geebt48cc

    geebt48cc Member

    Uno, from what I know, I've got to agree with AussieSteve. I even just might try something like that?!~

    PS-Motorpyscho, I agree with your point of the after affects of the 48cc w/expansion chamber. Zooooom-Zoooooom
  6. AussieSteve

    AussieSteve Active Member

    Gearnut has a point. There is some variance between manufacturers. Still, I reckon that top-ends from the same manufacturer will probably swap without problems.
    A head, barrel and piston is pretty cheap, to test the theory.

    Please keep us posted if you do it.