Fuel/air and spark....check for all three. Make sure you start with a dry, sparking plug, then push the primer for 2 seconds. pull the choke 1/2 to 3/4 up and pedal that sucka! 10 mph or more. Pop the clutch and work the throttle slightly. If after a few seconds you don't at least get a few pops, pull the plug and have a look. If it's really wet, you may have to re-jet to a smaller jet. Also if it's really wet, try the same proceedure as outlined above with no choke, wide open throttle.