Any time you have a no-start situation, it is best to "get the facts". You need facts, not speculation or guesses in order to accurately get to the bottom of your issue.
Your engine needs proper charge (fuel, oil, air) being supplied in order to run, along with sufficient compression, and ignition. Of course, it all has to happen at the right time as well. You'll need to check for spark, compression and fuel. It sounds like you have already checked spark, but even though you are getting fuel - are you sure there's no water in there, and no trash in the carburetor? Have you hooked up a good compression gauge and gotten a reading?
You mentioned "bent valve" in your previous post... Our 2-stroke Super 9 engines do not have valves like you would find in your car, but they do have reed valves (which break and fray, they don't bend and stay stuck in a bent position like metal 4-stroke valves might). I suppose you could check that if you are so inclined. Be careful about the gaskets... might want to have extras on hand before you take it apart if you suspect a broken reed.
If fuel and spark are okay, you may want to remove your exhaust, and look up into the port. From here, you can actually see the piston. You can't see all of it, of course, since you're only looking through the exhaust port, but you can see enough to tell if there are scratches or unacceptable wear on the piston. You can also see the boost port, and secondary transfers though the exhaust port. I'd get a compression check while you're at it. One with a real number attached - not the "It blew my thumb off", or "it didn't" method.
I consider it rare to have an ignition timing issue on a scooters, as the ignition timings are fixed and the flywheel keys really don't shear in normal service. That said, I think that if you have spark, you really shouldn't have to worry about the ignition timing - but I'd like to mention that just this week I had an air cooled Super 9 come into the shop that had a bad CDI... It still had spark, but it was firing at the wrong time, causing a no-start situation. On occasion it would even backfire really bad when trying to start.
On the note of CDI issues, you will want to make sure that you have a well charged battery. With your liquid cooled Super 9, you have to have a bit of power to run the DC powered CDI. It will not run well without a fully charged battery.
If you take this, and the other advice people have given you into good consideration, I think you'll be able to give us some good feedback. You should certainly be able to get to the bottom of the issue.
~Josh
