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?