I have a polaris 330 that has 165 psi compression, has good spark, and getting fuel. When i try to start it it backfires out of the carb. Like it is out of ignition time and it is firing on the intake stroke and not on the compression stroke. Anyone else have this problem? Is the cdi box bad even though it sparks? Any insight would be appreciated. Also it is the original cdi box.

 

Don't know that model but have had the odd Suzuki that sheared the key on the flywheel and the flywheel "turned" on the crank, far enough to put ignition timing well out. Had valve timing do the same thing on water cooled engines with no oil in them. Camshaft seizes and sprockets move round on camshaft. Once cool engine unseizes but valve timing is out. Air cooled engines without oil seize on piston rather than cam. Honda 250 cam chain tensioners break, also putting valve timing out.