Unhook the black/white stripe wire coming from the CDI box (it may be paired with a Black yellow wire, if so, unhook both). If it then has spark, the problem is in the kill circuit. Make sure the CDI box is grounded to the engine through the black wire. The problem could also be a bad CDI box or pickup/trigger coil. A continuity check could be done on the primary coil wires. It would be good for you to have a multimeter (can get a usable one at a discount store for $10) and a service manual (eBay).
If you have to pull the flywheel, it will be better to remove the engine because of the Venture's electric start- especially if you have not done it before. The fan housing, starter and motor mount have to be removed to get the flywheel off because of the ring gear. With a manual start motor, it is easier to leave the motor in.
