So I have this 66cc motor on my bike that I just installed, I have like 50 miles on it and the other day my bike started rattling when I have my clutch pulled in and increases when I rev it. However when I drop the clutch and put the engine under load it doesn't make the nosie until I get to high rpms. I have already checked all the bolts on the outside and opened up the clutch to make sure the screw wasn't coming loose. Does anyone have any ideas or suggestions? I would just hate for me to keep running it and completely kill the motor.