ptartp,

I just hold a finger over the exhaust exit for a second while spinning the motor over to prime it. I usually never do this anyways, unless it sits for over a week. I am using a Saito though so your engine may have different needs.

One other thing to note, check the interference between the carb and the motor mount screws. I had to replace one hex-head screw for the motor mount with a countersunk phillips head machine screw, so the carb wouldn't hit. Again, it might be different with your engine.