hey guys it turns over fine,has spark,and carb is perfectly clean.i was out riding it perfect and it turn off on me and thats the last it ran.what can it be?timing?can that lil computer thing cause it to not run

 

Pull plug,spray with starter fluid, reinstall and see if it will start. That should tell you if it's fuel or ignition. And since you have the plug out, check compression. Any gunk in fuel tank?. Is the fuel shutoff valve working properly?. Carb float OK?.

 

pop the hose off of the carb and see if you have fuel flow, it may be a plugged petcock valve, plugged fuel filter, etc.... it you've got spark-that's half the battle. when you say clean, you see daylight through all of the orifices on the jets, right?! when machine turns over, does it act like it is trying to fire or just turns over. let us know.

 

It back fires after couple of turns,but won't turn on

 

I would check compression if that reads low mostly you need to adjust the valves. your question about the cdi box the machine will never have spark if the cdi is bad or if it does very intermitent.

 

thank you i forgot what that was called,so check compression is my next big step.what numbers should i see on the gauge?

 

Normally most yamaha call for 120 and up. but evan if you have 105 or sumthin allittle higher it should run.

 

okay thanks will have to borrow a comp. gauge

 

went out and bought a compression gauge set,did a test and im getting about 101-102.is that enough to run?what sucks the most my extended warranty ended few months back

 

well i checked it