Reinvigorating a detuned Chinese 48cc engine

Discussion in '2-Stroke Engines' started by Devil's Advocate, Aug 29, 2015.

  1. Devil's Advocate

    Devil's Advocate New Member

    I have a 48/49cc (whichever it is) Chinese engine on a mountain bike, and it has been detuned to 200w which I think is about 0.3 horsepower, to meet with road rules and qualify as a bicycle. I'm 6 ft 2 and 230lbs, and the engine struggles when it comes to the slightest of hills, so i'd like to get a bit more power out of the engine.

    I believe the way they have restricted the power is with a restrictor on the exhaust, and possibly a smaller hole in the intake manifold gasket. I would like to increase the power of this engine as it is at least 1 full HP down on an unrestricted 48cc engine. I was recommended to fit an expansion chamber, which I intend to do, although the tuning side sounds potentially tricky. I was wondering if there are any other obvious mods I can do to this engine to free it up and get it working like a regular 48cc motor?

  2. crassius

    crassius Well-Known Member

    could be many things, including a spacer on top of slide to keep it from going all the way up

    I'd start comparing parts to pics on this board to find what is different
  3. jaguar

    jaguar Well-Known Member

    remove the restrictors
    take metal off the head to increase compression
    put an intake extender on it