Bike Wont Start, HELP!! PLEASE

what kind of engine do you have?

Have you tried pulling off the magneto case and checking for any loose wires? That is where I would start, um if you can try another CDI that might help but other than that thats all I got.

When you say you rebuilt the bike, do you mean that your rebuilt the bike, and then put a new engine kit on it?

I just got my first engine kit running last night after having multiple problems. Yes, they are very frustrating. But I figure you buy one of these cheap kits, so that you know what you want when you plop down some serious cash to do a really nice build.

Check that you have good connections on your wires. Don't use the cheap wire connectors that came with it. Make sure the blue wire goes to the blue wire, the black wire to black wire, and undo the kill switch until you get it running.

When you go to start it, make sure you're going down a hill.

Pedalling that thing back up the hill repeatedly the past two evenings has been a serious work out for my thighs!

Whats with the screen name? Yuck.

I used to mow lawns for a living. A tip for making the pull starts last longer: Use Silicone spray to lubricate the wrap spring and cord. If you know how to replace the pull cord, it is best to source some better quality pull cord right away and change it before it breaks.
If you don't have silicone spray or expect lots of dust/sand, use wax on the rope. Polishing the hole where the rope goes in while the rope is off, helps to prevent fraying.

If it breaks you can fall, hit your hand on something, drop the bike, or the wrap spring can unwind inside the cover on some types. (awful)