motor won't start

that happened to me on my first build due to crappy directions in regards to the wiring.. all 3 black wired get put together, then the off colored ones get grouped as well. If they aren't done right you're going to get the situation you're describing. If the wires are right, then it could be a bad seal. I got a 66cc motor last year that had a blown jug seal right out of the box, and had the same symptoms as well.. turning over but no spark, (bad wiring) or turning over with spark but no compression (bad seal)

if your ground wire is not in the right place it will not start.. on my first bike i tried grounding it on my front mount, and got no spark.. i took the wire off and the motor ran fine.
so i just started my bike with the ground wire un hocked to see if that was the problem. it was.

with the motor running, i held the wire on points with no paint, and hit the button till i found one that grounds right and kills the motor.

for me, my water bottle mounts worked great. and are under my front motor mount and out of sight...

hope its something easy like that and your riding again soon.

Gasket is in the correct place.
Cylinder stud/ head nut torque: 6mm studs@ 50-60 inch pounds, 8mm studs@ 150-200 inch pounds.
You need to determine what size of studs your engine has. For reference, the carb, exhaust, and motor mount studs are 6mm. If your cylinder studs are the same size then you have 6mm cylinder studs. If they are larger then you have 8mm studs.
Be very, very sure that the studs are all the way into the engine case before torquing the cylinder head nuts or you risk pulling the threads out of the case if they are not fully threaded down properly. I tighten them all the way down into the case then back off 1/2 to 1 turn. You want the teeny bit if room under them for thermal expansion/ contraction purposes.

that extra white wire isn't a ground. it's a 3amp power output to run small lights from. Black to Black to Black (kill switch wire) blue to blue to whatever color the other killswitch wire is. I generally tuck in the white wire and heat shrink tube that one shut so I can always cut the wrap off later and use it if necessary. As for the motor jug bolts.. I always switch mine out with the higher grade ones via sick bike parts, as I have stripped countless threads on the cheap aluminum ones or low grade steel the kit supplies. Generally I swap out ALL of the bolts (particularly the chain tensioner ones) as well as re-gasket the kit before I install as those are the most common trouble spots in getting these things to work..

I had the simliar problem I got fed up and bought a new engine and today i pulled my bike out to try and get it starded before my new engine gets here . My rommie came out and schooled me on sum electrical stuff, the coils wire black/blue to the cdi case and white from the coil I had to disarm kill switch cuz my new cdi dint have the connections for the kill switch but my roomie told me the black wire needed to be switched w/white wire goin to the cdi and so i did and it started rite up . So now I'm gonna have 2 engines to play with and sum more knowledge and you cant beat that with a stick right.