Petcock rebuild

[jlmoulto]

Mine started weeping gas after I took it off to clean the screen. Would the petcock rebuild kits do the trick or should I bite the bullet and get a new petcock?

[earlfor]

Re: Petcock rebuild

I estimate that 90% of the time, when a petcock starts leaking, the problem is a single "O" ring has bitten the dust. In your petcock, open the back, you will find a diaphram, underneath, a spring, under that, a small plunger that fits into the fuel passageway. On the end of the small plunger, there is an "O' ring. Most of the time, and even when a rebuild kit still results in fuel seepage, it is that "O" ring that is incorrectly sized. If you take your plunger and petcock assembly to the dealer and match up a well fitting "O" ring to the passageway. I thinnk your problem will be solved.

Some rebuild kits are notorious for crap "O" rings.

Earl

Mine started weeping gas after I took it off to clean the screen. Would the petcock rebuild kits do the trick or should I bite the bullet and get a new petcock?

[frosty5011]

Re: Petcock rebuild

Mine started weeping gas after I took it off to clean the screen. Would the petcock rebuild kits do the trick or should I bite the bullet and get a new petcock?

Is the leak in the petcock itself, or from the larger oval shaped gasket between the petcock and the tank? You didn't say if you had disassembled the petcock itself.

[jlmoulto]

A bit hard to say where it is leaking as the entire petcock is wet. I unscrewed it from the tank so it probably is the main gasket between the tank and the petcock. I did loosen a couple of the other screws on the petcock as well until I realized I was moving the wrong ones (oops!) so I guess I may have damaged that seal as well. Are the rebuild kits good, generally?

[my98xplorer]

I bought a petcock rebuild kit for $9.99 on Ebay and it worked great! No more leaking gas everynight and no more starving the bike for fuel. Everything is great and it beats spending $100 for a new one!

[Anonymous]

earlfor, would that fix apply to a petcock that won't shut off but otherwise has no (external) leaks? Mine (79 850) leaks into the carbs after every winter's draining and was rebuilt 2 years ago.

[earlfor]

I would think your problem would be either the plunger "O" ring or a weak spring. since the petcock works in vacuum activation, I doubt it is a holed diaphram. Most likely, a new "O' ring will fix it. If it doesnt, youre only out about 25 cents. :-)

Earl

earlfor, would that fix apply to a petcock that won't shut off but otherwise has no (external) leaks? Mine (79 850) leaks into the carbs after every winter's draining and was rebuilt 2 years ago.

[Anonymous]

earlfor, thanks. I'll change out the o-ring and check the spring tension.

[Anonymous]

earlfor, seems to have worked OK, no leaks after 1/2 hour of running. Changed the o-ring and stretched the spring a bit. Hell of a fix for 19 cents!! Thanks much :P

[Anonymous]

I have found a way to make the little troublesome petcock not so troublesome (and much more peace of mind too).

I purchased a fuel shutoff selenoid valve from a local auto parts store. It is normally closed when unenergized. I cut the fuel line between the petcock and carb inlet and placed it there. using a relay I wired it to the key switch so when the key is turned on, the selenoid is energized and opens, allowing fuel into the carbs.

A cheaper fix ($40) then buying a new petcock ($80), and if your petcock doesn't leak through now, it won't have the chance with the selenoid valve as a backup.

[Anonymous]

The petcock was unscrewed from the tank: what size replacement petcock could be installed in its place? (i.e., thread size). Thanks.



Bustedfeet.

[Anonymous]

How can you tell what size O-ring if necessary for the fuel valve without taking it apart? And where do you get a new one?

I would think your problem would be either the plunger "O" ring or a weak spring. since the petcock works in vacuum activation, I doubt it is a holed diaphram. Most likely, a new "O' ring will fix it. If it doesnt, youre only out about 25 cents. :-)

[Anonymous]

vanzetti, you can't. Gotta take it apart, and go to your local NAPA or other parts store with the o-ring and match it up.