Good luck getting any 2010 or later Skyhawk motors for anything resembling a fair price if you can find a new one at all, last I heard they have all been sitting in customs for months with no release date in sight.
Go through the order process at gasbike/kings for yourself and you'll see.
I take it you want to make powerful racer, don't be bike stupid with your base. A $100 wally world bike will tear itself apart before you even have the motor broke in.
I really should be documenting all the schwinn and huffy bikes someone else build I have had through my shop with the most common problem, the back wheel gives out.
Sure, pretty frames but they are weak and they break too, but the wheels are garbage. Go ahead and invest in a new good rear hub or even bearings and axle if you want but if you crunch the numbers you will find the difference between a $100 bike and a $160 bike is a penitence when you get to replacing the tires and wheels, you just spend won't hours stranded and fixing **** and you still have the weak frame problem.
Really dude, **** bikes barely hold up to people pedaled 1/4HP, you try throwing 3+HP on one and you aren't just asking for heartache, you are guaranteed it.
Just my 2¢ after more than 2 dozen new builds on solid bikes and a dozen repairs, or in the case of the brand new Huffy sitting here with a ruined back wheel before the tire nubs were even worn off being completely stripped and put on a solid Macargi bike.