if the float is stuck low in either carb float bowl there is an overflow tube that goes down just above the top of the crankcase on the right side of the bike.
If the tube is in place and not crushed it lets the fuel leak out where it wont hit the exhaust and combust into flames
If that tube is pinched off I guess its possible the carb could fill to the top with gas, but I think it would also fill the cylinder with fuel, ruining your oil by dilution.
you said you took the front float bowl off, it could have been the rear float that was stuck
those clamps on the bottom of the air box can be a PITA sometimes to get back on - you tighten the screw.. almost snug... and it pops off.
I think over time and heat the airbox deforms and no longer wants to sit in place
try cleaning the top of the carb, the inside of the airbox, the clamp.. with alcohol and wipe it all down dry so its plastic to metal contact, with no oily gas acting like lube. The engine breather hose goes into the airbox, venting the oil fumes from the crankcase, so the inside of the airbox normally gets oily.
Reading your post again, did you see gas leaking out of the bike anywhere?
with a carb'ed engine its normal for it to smell like gas when the engine is hot. The gas in the float bowls literally boils out when the bike is parked hot, and you smell the fuel vapor coming off the engine.
That does not happen with fuel injected vehicles, so most people are not use to gas engine smelling like gas anymore.
one more thing - if this is the first time you rode this year, your gas has probably turned goopy unless you used a fuel stabilizer in the tank when you parked the bike for the winter.
if you did not stabilize the fuel when you parked it last fall, I would drain the tank, fill it with fresh gas, and use something like Seafoam to clean out any gunk in your carbs. As long as the bike will run Seafoam will do the job.
If you cant get the bike to start again it may have sucked some goop in from the tank. In that case you will need to get some seafoam into the float bowls, and let it soak overnight.
Last edited by KCW; 08-08-2019 at 02:19 PM.