Re: 42 miles of He.....
I think these motors were governed at the factory for a reason. They can barely take the power they pump out stock, never mind all these porting jobs & whatnot.
The thing about the SkyHawk verses the other engines isn't in the engine itself. I've worked on 4 or 5 of these motors that kids have around here (all from different sources), and the best built one I've found yet was a no-name one on eBay I bought from BGF. The kit itself sucked (they wanted me to drill through the frame, and the exhaust was a P.O.S. and the cap fell off after 5 or so miles) but the motor seems to pack more of a punch than the others. Bigger ports, square clutch pucks (if you do the math it translates into more surface area), and it's real easy to tune. I think the SkyHawk comes with the nicer kit, the motor is just the same cheezy motor as the rest.
The motors are meant for 2 kinds of people. Either someone that really wants a project, perhaps for their kids or just something cool to built on the cheap OR someone who needs a way to commute & can't get a real vehicle cuz they're broke as **** (like me). Riding a crap 4-stroking motor is a heck of a lot better than peddling a 20 mile round-trip commute to work.