I recently purchased a 49cc from PowerKing off ebay and had the same problem. I called PowerKing and they had me turn motor on its side and put my full weight on clutch lever. (By the way, I did this before mounting the motor) It worked! Was stiff for a few more tries but then loosened right up and is free as a bird now. I think maybe they just seize up from setting on the shelf. GOOD LUCK! P.S. check for air leaks around the intake, as that was another problem I had with the PoweKing. To fix, I removed the intake and put on Black RTV and replaced intake. Works like a charm now.