If the carb bowl fills, then it should start. unless bad gas, plug or carb.
Check if the plug sparks.
Check battery, alot of times the battery has enough to turn it over but not start.
Or try push start. My method is different from rest. search for theirs if you don't like mine.
with clutch disengaged and in 1st gear.
pull out choke if you like, twist the throttle a little.
push bike like the devil
hop on, push the starter button for a rev or 2
and let out the clutch.
pushing the starter button kicks in the decompression so it's easier to start. letting out the clutch turns off the starter. which takes the load off the battery. now you should have enough juice to run.
keep in touch