If it turns over (starter is working) and you placed the spark plugs next to metal and see an arc (spark working) then you are not getting any fuel.

I dont know how many times I will have to say this, but valve clearanced will not all of a sudden make a bike stop running. It may run like crap but it will still run. Also, you are not going to all of a sudden lose all of your compression unless there was a catostophic engine failure.

Start with your fuel. Make sure that fuel is freely pouring out of the petcock and that the tank is suffiently vented.

 

Spark could be very weak as well, even if it looks like it is there.

On my F2, the engine would crank slow, then start most times after a few seconds. I thought it was normal as that is how my bike always started. (bought used) After a while I found it easier to push start the bike as it would fire right up. I went to ride this fall after three days of no riding and the starter wouldn't even crank. Picked up new battery and the thing cranks super now and fires up in a split second.

The moral of the story was that while the battery still had juice, the voltage needed to produce a good hot spark while the bike was cranking just wasn't there. The battery would test at 12.8 sitting, but when load was placed on the battery, it would drop like a rock. -Check the voltage at battery while cranking.

 

If there is a weak spark, try taking the plug wire apart. Check the resistances of the wires. You can unscrew the head of the wire (up inside were the head of the spark plug goes and you should find 3 parts. a spring, a rubber insulator and a resistor. Make sure all the resistors are giving off the same reading and re assemble. On mine, the rubber insulator was stuck not allowing the resistor to actually make proper contact with the wire and the plug.

 

I've read on here where guys couldn't get their bikes runnin and when they put in new plugs... the bike started right up. You could have weak spark due to worn spark plugs and also because of a weak battery. How long have the plugs been in how old is the battery? I've taken my batteries to a auto shop to run the battery through a diagnostic. They need to know the cold cranking amps (CCA) which is 120. I had a problem just like what MikeInCtown had where the battery would read fine voltage wise but fail when under a load.

 

I also like the idea of weak spark. I have seen that problem before. Have the battery load tested.

 

and if your plugs or wires look bad i cant hurt to change them.

 

i'm not the original poster, but i did get my bike running. it turned out to be a weak battery and the voltage was dropping when i would crank it.