How big is your track? I have to say it's hard to believe it has as much top end as a sirio but I still have to finish break in.
You're right about the engine being hard to start. You have to lean the high end needle quite a bit to make it start.
I've gone through about 15 minutes on the starter box full throttle four stroking. I know this thing is going to have massive low end power but that's not as important to me.