That's a great price. Is this a new, in the box, kit?
Skyhawk & Starfire are Grubee brand names. I have several of these 48 & 55 cc engines. I wouldn't say they are any better than other brands, but will say they are as good as any out there.
You can expect to run 26 to 32 mph top end. (depends on rear sprocket size)
check this out-----> http://www.motoredbikes.com/viewtopic.php?t=1010
I am replacing the engine on one of my bikes i had 2 80cc bikes but i had a piston shatter in one of my engines so i took parts from the other to fix the broken engine and now the piston is poping up above the head i think because i have a piston from another engine it think its a spitfire engine piston and the engine jug and lower half i have it on is a daxs so i have to try buying a piston from thatsdax.com and see if that fixes that engine. I figured so that i have a bike for the summer i mine as well pick up that engine until i either fix my 80cc or buy the 4 stroke kit that i want to get, just cant afford rite now. I loved my 80cc bikes i wish they were still working hopefully i can fix the one i have with just a new piston. kings motored bikes said he would sell me a replacement 80cc engine for 145 shipped so i may just end up buying another 80cc making that the 4th 80cc engine i bought lol