Some tricks I used to use when starting big bore finicky 2 strokes:
1) Try tipping the bike over on its side, until fuel dribbles out the carb over flow.
2) Stick the bike in gear and rock it back and forth a couple of times. This will get a fuel/air charge into the cylinder.
For either method, make sure you ratchet the kick start lever all the way up before you kick it. You can often "feel your way" to catch one more tooth on the ratchet system. This can help immensly.
Street bikes for the street. Dirt bikes for the dirt. Let's keep it that way.