You could check the timing, it wouldn't hurt. But the main jet has a series of small holes that go up the length of the jet, if the higher ones are clogged but the whole jet isn't completely, then that could also be your reason that the engine might not be getting enough fuel to hit power band. At least I think the jet should have those holes, my bike doesn't, but like I said, I'm not a Maico pro by any means.