I have a SkyHawk GT5A 66cc engine that has at least 300km on it. After replacing the stock carb with a CNS high performance carb and boost bothe I took it out for a 10k ride, all was well. The next day I go to start up the engine. It had a much harder time starting and when started it barely revved high enough to get into gear even at full throttle let alone idle and the engine was shaking more erratically than it used to, I thought, probably something with the carb, so I check for any blockage and drained it. No problems. I checked the choke and throttle, both perfect. I checked all my connections to the carb and all was good. So I tighten all the mounting bolts and such, no issues there either, so i checked for exhaust blockage, no blockage other than the exhaust is a little lighter. but I'm still stumped, could it be internal damage? If I block the fuel source it will rev almost as much as it should but let the fuel flow again it loses almost all power, could it be a head or gasket issue? I don't know I've tried everything but I honestly don't know what could have caused it from perfect functionality to barely running.