I have been given a motorised bike to fix and got it running perfectly, then I come back 4 days later of not riding it and the bike was really hard to start and then stopped working. So I tested the spark on the top of the cylinder head and had no luck. I brought a new magneto, a new cdi and a new spark plug, but it still won't spark. When I ride the bike I hold the clutch in, petal, let go of the clutch, I know that the pistons are moving and that the bike has compression. Inside the magneto case there is rust on the magnet that spins and I'm not sure if it is effecting the ignition. Could someone please help me!!!