All built but no combustion!

something you might want to try. first use an ohm meter on the wires from the mag coil. you might have a bad connector if so remove( cut off) the connectors on the blue wire and the black wire. replace them completely. soldering new connectors along with crimping them. don't hook up the kill switch for now. make double sure the bare copper wire on the magneto is still soldered to the coils frame (you might need to look real close as sometimes the solder job is poor or broken.

with the meter set to ohms put you meter on the blue wire and a frame ground you should have around 300 ohms or more.check the white wire to ground on the frame should be around 2.5 ohms do these with the cdi disconnected.
make sure the spark plug wire is tight in the plug boot and the cdi,both screw in with right hand threads.
spark plug gap about 0.025" use a clean/ dry new spark plug
once you have the blue to blue and black to black connected from the cdi to the mag coil lay the spark plug on the cylinder head so you can see the spark plug electrode. You will also need to have the spark plug hooked up the the spark plug wire for this quick test.
roll the bike forwards while looking at the spark plug with the clutch let out so the engine will turn over you should see a spark and might even hear it if your hearing is good.
if you get a spark hook up the kill switch one wire to either the white wire or the blue wire. if your kill switch is a 2 wire then the loose wire can go to either the bikes frame or hook it to the black wire that also hooks up to the cdi. roll the bike again if you have spark still then put the spark plug in and give it a try.
I didn't tell you how to test the cdi as I do not remember the ohm readings for it. I think fairracing has it posted I just don't remember where right now
You can get a cheap ohm meter at walmart for around $15.00 might be a little more but if you can afford it go for a good meter as once you have one you will use it on a regular basis if you plan on playing with these bikes.
I had a connector that was crimped on wrong insulation was not removed and couldn't tell it by looking at it. Also the bare copper wire on the mag coil on some have had a very poor soldering job it looked good but was not. Hope you can find the problem and I hope its just a bad connection that will be easy to fix. The worse case is the cdi is shot. If you have a friend who has a good cdi and you have done the testing on the mag coil its easy to swap out a cdi to try on this bike. Only 2 wires and the plug wire to change out for just a test I don't even mount the cdi I just let it hang for testing.
Other problems could be the mag rotor has a sheared key. You might also take off the mag rotor mark which side is out first then take the rotor off flip it over and see if it will fire I've found out one one of my engines it makes a difference I still haven't tried it on some of the other engines. To keep the wood ruff key in place while reinstalling it use a touch of super glue to keep the key in place the magnetism of the rotor will try to pull the key out of the key way and can be a real pain in the rear.