I have a stage 2 clone from these guys
http://nr-racing.com/Clones.htm
Motor has been a perfect idle and pulls strong since the first start, was on my son's yerf but was a little too much for him so I pulled it off and replaced it with an electric start 6.5 motor
Ended up putting it on my trail bike with a comet TAV 30, to say the least it's a wild ride
Here is a vid of it running, I have since then replaced the header with a much better one
http://youtu.be/kG3sEdGg6u4