Gas leaking from carbs into airbox

[Nessism]

Wondering, just what "safety" there is in a vacuum operated petcock. If they were such a wonderful idea (and they are, when they work) you'd still be seeing them on new bikes.

My understanding is that modern bikes DO have vacuum petcocks. At least my 2004 EX500 had one. \\/

Vacuum petcocks are a safety feature because when a float sticks open the float bowl overflows and dumps gas on the ground. Gas on the ground is a fire hazard not to mention the fumes are harmful as well.

[Giblet]

My understanding is that modern bikes DO have vacuum petcocks. At least my 2004 EX500 had one. \\/

Vacuum petcocks are a safety feature because when a float sticks open the float bowl overflows and dumps gas on the ground. Gas on the ground is a fire hazard not to mention the fumes are harmful as well.

The STATED reason I've seen most here for replacing the vacuum operated petcocks is reliability. Gas ends up in the crankcase or ground when they fail which seems to be a common problem no matter the make of the bike. Maybe this is a good idea for a poll. Any how, Google "vacuum operated petcocks" and see what comes up. My apologies for not researching my topic properly. Apparenly some new bikes DO have vacuum operated petcocks, and, they seem to all have reliability issues. Vacuum operated petcocks may be a convenience but I would definitely not classify them as a safety feature. Fix your problem once, or fix it again & again . . . .

[Alixn]

Okay! Me again and I've got some pics. I (finally!) received a petcock from Flat Out and installed it on the fuel tank. I opened up the "old" petcock and took some pics, hoping that someone can tell me if it was due changing or not, if one can tell from these pics at all.

[tconroy]

You changed it ,that's all that matters.If you have gas in the airbox it's from your o-rings in the needle valve seats.THey are cheap and easy to replace.

[Killer2600]

I can't tell from those pics, if the diaphram has a hole in it or if the rubber ring or seat is messed up then yes you did need to change it. Basically if it leaks it needed rebuild or replacement.

[Alixn]

Ok! You're right, it's changed and that's what matters.

I have other questions, this time relating to needle valves. As Robertbarr suggested, I took a look at my needle valves. One is scored so is definitely being replaced. One looks new and the other two... well that's were I have questions. They are not scored, yet they show a ring, possibly at the position where they mate with their seat.

1) What could the ring be indicating?
2) Do they need to be replaced?

One thing I need to remind here is that I do not know which carbs are leaking. I'm taking for granted that the scored one is shot and can't possibly provide a good seal. Oh btw, I also have 2 seat o-rings that are cracked: one on the scored valve, and the other on one of the "ringed" valves.

I know the obvious and easy (and expensive) solution is replacing all four needle valves and seats with OEM parts. But how can I pinpoint the problem without going to a local shop?

[tconroy]

The needle valves and seats are not that expensive and getting new ones along with o-rings will solve your problems.That's all there is to it. Replace them and you will be fine.

[Alixn]

Hey

Got everything changed. It almost seems like the engine is running smoother ?!? Probably just an illusion. Anyway, thank you all for your helpful comments.

[tconroy]

No,it is running smoother!!!