Help! Why isn't this thing working!?!?

Hi guys,

I bought a used motorized bicycle and it's been nothing but trouble. From what I was told it is a "80cc" RAW 2-stroke engine kit (though I know apparently the actual CC's are less). I never had one of these things before so at first it kept dying on me, but once I got the hang of it (or so I thought), it seemed to work OK. Then it started dying on me (one and off) again.

I removed the spark plug (thinking maybe it was going bad) but couldn't find a replacement; then I put it back in and it hasn't been working since. It seems like the engine is turning but it wont fire up. On top of that somehow my electrical (which the guy before me had wired precariously) had come apart so I put it back together based on the wiring diagram circulating online (black to black, blue to blue, with green spliced into black and red/yellow spliced into blue).

So now I really can't tell what's going on. Did I somehow mis-wire something (I checked and it seems to be OK), is the spark plug not inserted correctly (how can I be sure if it is?) or is the engine flooded? Essentially, when I try to start it, I can't tell what the problem may be of those three things. Also, the fuel line seems to not be letting fuel through sometimes (as if there were a vacuum).

Can anybody suggest a systematic way for me to be sure which of those things work/don't work so that I can isolate the problem?

Thanks a lot, any input would be greatly appreciated!

-Tom

OK guys, thanks for the tips. I made an investigative breakthrough that I think may solve the problem.

I had told you in the first post that the wires had come undone and I rewired them correctly (according to the RAW manual), which was black to black, blue to blue, ground (green) spliced to black and the red-yellow cable spliced to blue. (I used follow the wiring schematic found here:
Wiring 2 Stroke RAW Engine Kit)

Anyway, I just found out that when purchasing the bicycle somebody had taken a photo of it and, having enlarged that photo, discovered that the guy I bought it from had green spliced into the blue wire. It worked that way (I bought it after test-driving it for a while), so I'm assuming he put the wiring together correctly but reversed the colors.

I have two questions:

Is it a safe assumption that he did in fact just wire it correctly but reverse the colors?

After the cables came undone and I wired it "correctly" (according to the schematic), is it possible that I actually damaged/blew out the CDI (the black electrical box)?

If I may have blown that, is it possible to buy those somewhere locally in Los Angeles and how much are they? Is it worth it to replace it or could mis-wiring be too costly to repair?

Sorry for all the questions; I'm at my wits end with this thing. Thanks biknut and Venice for the reply.

-Tom