You know, they really should have big warnings on these kits: Every piece of mounting hardware and cylinder stud in this kit is made from recycled soda cans. Our workers frequently leave metal shavings and other bits of trash inside motors, thoroughly disassemble and rework upon receipt.
But besides that. What you'll want to do is dismount your motor completly, put it on your work bench (Or kitchen table, lacking a work bench) unbolt the cylinder head, and try and slip the cylinder off the piston. If it won't go, spray the piston down with some WD40 and let it sit overnight.
If the cylinder DOES come off the piston, your problem is somewhere else in the system.
While you're waiting: Read every single thing you can about these motors, they're not toys and they're about as far from maintainence free as you can physically get. If you've not got the stomach for a challenge, or some major retooling work, send it back, get your money back, and spend it on something else, because these bikes aren't for the faint or heart or the mechanically disinclined.
