2004 arctic cat atv 50 2 stroke

can a coil still work but wont let the atv start

I have no specific knowledge about that vehicle but if you are getting a spark at the time of maximum compression, the coil is working properly. You can have a spark at the wrong time and it wont start because the timing is off. If that is the case the timing chain could be off or it needs the timing set.

One cycle in a typical gasoline engine:

* Intake: Valves open and draw fuel/air mixture into cylinder.
* Compression: Piston comes up and compresses fuel/air mixture.
* Ignition: Distributor triggers coil and creates spark, exploding fuel and pushing piston down.
* Exhaust: Burnt gases expelled from cylinder.

All of the things above must happen at the right time or the engine won't run.