250-500cc Gas spilling out of vent hoses

Hey guys. Was down in the desert this weekend. I didnt get to ride because when I turned the gas on, after a second or two, gas started pouring out of my vent hoses. I have an 09 300 with a Keihin PWK carb. But I assume the general function of the stock carb is the same. Float bowl? If so, what would cause it to stick? I haven't had a chance to pull it apart yet, but figured I would ask if anyone else has ever experienced this.
Also my fuel petcock is dripping. Slowly when in the off position, and pretty steady when I turn it on. This confuses me. Is there a gasket kit for these, or am I best to just pull it apart and go to the hardware store and try and match it up?

more than likely a piece of dirt is stuck in the float valve,I 've had it happen,usually just keep tapping on the side of the carb with a something will stop it.If not pull the carb off and clean it.

I did try that when i was down there with no luck. Ill clean it out proper. Any ideas about the leaky fuel petcock?

try tighting the 2 screws on the petcock itself,it just a rubber seal behind there

Did that too.... Guess i will have to drain tank and pull it apart and try to find replacement gasket/o ring.

If the float neddle is sticking in the seat put a qtip in a cordlees drill with some mothers polish on it and polish the seat that has solved that problem for me a few times...!

That is pretty slick right there. On further inspection of the gas...there is some fine red dirt in it....wtf. Not sure how it got in the tank. Only way would be the vent tube. Anyone ever have that? It was really dusty where we were, but taking gas straight from tank and letting it settle 3 times produced a small amount of red dirt at bottom of container each time. And its 110 octane. Not cheap gas, fresh from pump. Gonna have to empty/ filter gas and will for sure be adding an in line fuel filter to the bike too.

There s a small o ring on the petcock where it meets the tank, not uncommon for them to fail ( thanks ethenol!).

You can get it any dealer.

I like running a fuel filter.. It's a Visu-Filter.. Got mine from Scott Rocher but also available at Dennis Kirk: Part # 180204

Actually quite amazing what can collect in it.. Also a good visual check if you forgot to add oil (my gas turns red)..

Thanks guys. Looks like I will be doing some wrenching. I have another trip to the desert planned next week, so I need to dust/dirt proof my bike. Better than my friend with an orange 300 though. He shattered his piston. I said, shattered? His response...in his words..."in at least a hundred pieces and I'm still pulling pieces of metal out of the cases" So yeah. Could be much worse!. I will let you know if there is anything odd i find. It looks like my petcock is leaking from the part that spins, not where it meets the tank. Will let you know what i find

Jet rich for the desert

So I filtered the gas in my tank through a coffee filter and there was definitely a lot of dirt in there. Banged on the carb with a wrench to knock the float bowl free. It worked! No leaking from the overflow tubes. Took apart the lever on the petcock and cleaned out all the dust/dirt in there and voila....smooth turning and no leaking. Amazing how that super fine dust works itself into everything! Off to go get an in line filter and hopefully get a ride in soon.
Thanks all!

In a keihin pwk w a 38 pilot and jd red needle.

dont use a paper filter as i have heard that it soaks up the 2stroke oil.filter fuel before mixing in oil&dont empty last cup of fuel out of gerry cans when re-fueling

next time you could clamp the fuel line leading to the carb with narrow nose pliers and then quick crush the pipe further down with ordinary pliers forcing the fuel passed the seat under a small amount of pressure hopefully enough to move the debris.