Topic: Petcock pissing in garage

[SG103]

The petcock on my CB750F will piss on my motor overnight after I put the bike in the garage and shut off fuel. Anyone else have this issue? When I go into the garage in the morning there is a strong smell of gas.

Arnold

[Smudgemo]

I recently put a NOS 750 petcock on my 550F and it definitely does not close off the fuel supply.  About half the time the carbs leak fuel when I roll it out of the garage, and sometimes it drips in the garage.  I guess I've got two fixes to address.  Replace or rebuild the petcock, and figure out which carb(s) are not sealing properly.  The carb issue is a pain, but not unexpected.  The petcock not properly working really annoys me, though.

[strynboen]

some years have a plastic cone valve..and they can easy vear aut and internal leaking through the tap..and fill the carbs or leak.(.74-76 modells)..i think.. and is not to  easy to fix.
later plate type vith 4 holes is easy to go on..just a nev rubber plate.(rep set).and it vorks fine

[flybox1]

Rebuild it.  Worn internals.

[Gene]

A quick fix - tho not permanent by any means - is to create a short piece of fuel line and run a "U" from one petcock outlet to the other. You can do that while you're waiting for your replacement petcock, parts, or for storage.

I know this doesn't help, but again, a short-term storage fix.

[johnbkobb]

Where are the carbs leaking from? bowl seal, overflow tube?

[carnivorous chicken]

750F petcocks are riveted, not bolted together (at least the ones I've seen, from 75-78). And there is more than one size -- the medium size being hard to find, although I bet someone here has a line on them. The overflow at the carb may be exacerbated by a petcock that doesn't turn off, but it's its own problem.

[jgger]

Try shutting the gas off and letting it run for a bit before you shut down the motor and park it on the center stand. Running the fuel down in the carb bowls can rule out heat expansion of the fuel if the floats are set just a tad high.

[flybox1]

Not his carbs....his petcock

The petcock on my CB750F will piss on my motor

[carnivorous chicken]

Not his carbs....his petcock

The petcock on my CB750F will piss on my motor

Ahh.. I made that mistake too, but it was from the second post.

One thing to try: on the CB750F there is an o-ring where the petcock mounts. I had a leaking petcock but it was just that o-ring, and before I replaced it it was a little hard to tell where the leak was from. unless you're sure it's coming out of the petcock body, might try that first.

[flybox1]

Not his carbs....his petcock

The petcock on my CB750F will piss on my motor

Ahh.. I made that mistake too, but it was from the second post.

One thing to try: on the CB750F there is an o-ring where the petcock mounts. I had a leaking petcock but it was just that o-ring, and before I replaced it it was a little hard to tell where the leak was from. unless you're sure it's coming out of the petcock body, might try that first.

Yes, and you are correct that they are riveted.  Had to check mine again last night.
If that o-ring(K7/8s, too) between the pet and the tank is chewed up or disintegrated, it will easily leak around this collar. 
Viton/Buna are the best options here.

[strynboen]

you can drill the rivets and drill and tap the holes to a 3mm schrev/...

[carnivorous chicken]

you can drill the rivets and drill and tap the holes to a 3mm schrev/...

Also true. The round rubber bit inside with the holes (I know, technical term...) is replaceable on some, but I think the medium sized one is tough to find. I can't remember the measurements on the tap on these petcocks so I'm bring vague -- anyone else here help? the larger and smaller sized ones are available as repops for about $20, but I've had trouble sourcing the in between one.

[lrutt]

You can drill the rivets then tap the hold for a small screw. I've done that many times. Of course after you've replaced the holey donut inside.

[carnivorous chicken]

You can drill the rivets then tap the hold for a small screw. I've done that many times. Of course after you've replaced the holey donut inside.

That's the technical term I was looking for.

[SG103]

Thanks to all who have replied. If I line up the start of the notch on the handle with the "R" in RES, it doesn't leak at all, so not quite pushed to the end, and the fuel IS shut off. I will go with that for now. I notice as soon as I walk in the garage if it's leaking, gas smell.
Arnold