I have a 66cc 2 stroke bike that won't start. It has spark, it has compression, and gas is getting to the engine. The only thing I can think of is timing. Does the CDI control timing or the magneto? How do I test? It was worked fine for a long time. I shut it off and went to start it a few minutes later and nothing happened. That happened a few months ago and I have been trying to fix it since then. Any suggestions?