Hey there..did you ever get this problem solved and if so what was the solution? I have the exact same problem, vent line dripping, etc. I hooked a booster up to the quad and it starts immediately. I'm not sure if its the battery, coil, spark plug wire...? Thanks for any feedback

 

A possibility that has not been mentioned, are the crankshaft seals leaking. On two stroke seals must hold vacumn and pressure. If they are leaking when bike is brought up to temp it will make it hard to start. When cooled down they are sealing. Also when jump starting you are cranking faster and possibly overcoming part of the leaking problem. TORK.

 

Another possible cause not mentioned is the fuel filter.