possibly CDI problems

[collins_123456789]

i have a 138cc pit bike and a few months back i put an innor rotor kit in it and when i first put it in i had a few problems getting it going and had to change the CDI unit twice and just play around with it for a while to get it going. last time i rode it i had it going flat out up a straight and then i stopped revving it to slow down and then when i went to get up it again it just died, when i got home i played around with it and i noticed the spark plug was loose so i tightened it and tried to start it but it wouldn't start. it is defnitly getting fuel and it has spark, i was talking to the shop where i bought it and he said evan though it has spark, it might still be the CDI unit,
does anyone know what else could be wrong?

 

[pbk]

sounds like your valves might need doing, how old is your bike

 

[red_demon24]

yeah def check the valves.
my bike did similar thing checked the valves and they where too tight loosend em up a bit with a set of feeler gages and now it runs good better than it ever did lol

 

[collins_123456789]

yeah i checked the valves and my dad did something to the because i think they were tight or something and now it has heeps more compression but it still won't fire.