I've got the exact same problem! My sons quad is completely stock though. After bashing my head into a wall trying to figure this little machine out, I'm leaning toward the flywheel key. I have a brother-in-law that has to replace his in an old Blaster fairly often. Could the flywheel key cause the no start? I'm getting fuel and spark....and a slight hit once in a while, but no start. If the flywheel key is sheered, would there be any spark at all?
Oh, I also have some oil on my spark plug..is this normal?

 

I have since replaced everything back to stock condition with the exception of the restrictors leaving the main at a 75. Still nothing. I am going to try looking at the timing this weekend.

 

I DID IT!!!
I bought a replacement base gasket and some new gas. When I removed the head AGAIN....I noticed alot of carbon build up in the ports so I removed the cylinder and noticed the base gasket was leaking. I also took some gas from the tank and poured a tiny amount onto a napkin and tried to alow the spark plug to ignite it (nothing) So I went to the gas station ($3 later) tried the same exact experiment and perfecto.. the spark ignited the fuel immediately. I put everything back together and would you believe this....The bike started first pull!!
Thanks everyone for your input I don't think I would have gotten it running without your help. LASTLY...The bike sold last night minus the CT kit so I just bought the Jetmoto 110.

 

What do you want for the ct kit?

 

hi could you have a faulty plug lead when you move it it sparks when you put it back in it doesnt just a thought

 

I have a 50,does the same thing, any help yet?does it have reeds?

 

It's been 5 years, they prolly got a 450 now...