Is the exhaust just putting out a little smoke or is it fuming? A little bit at first is probably not anything to worry about.
Break in is sort of an extended process. Ride it light for about 10 miles or so then start riding like you normally would. I used a 20:1 mix with fossil oil for the first two gallons, 25:1 with the same oil for the 2nd 2 gallons and then 30:1 with good synthetic oil from there. The fossil oil allows the rings to wear in properly.
I personally think that anything over 25 mph on a motorized bike is a sure indicator of suicidal tendencies! These things simply aren't safe at much over that!
If it can't be broken I'll find a way!
I'm not lost, I'm exploring!