fuelcock/petcock replacement

[rphillips]

Unbelievable how things have changed. These new complete petcocks are priced lower than the rebuild kits. I've found the same with some bike master cylinders, Just hard to imagine complete new part cheaper than the few little parts in the kits...Good luck pep, hope you never even get to try the 2nd & 3rd that you've ordered. Awaiting updates.

[bwringer]

Last night I ordered three vacuum petcocks from three different vendors ranging in price from 17 to 27 dollars. As they arrive I will put them on the tank, now removed from the bike, and put in a couple of gallons. I am looking for a completely bone dry fuel nipple after several days of sitting both in the On and Reserve positions. If none of these produce that, I will order some more.
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I like your style, Don. Sometimes you just have to do the science if you want dry nipples. We anxiously await your findings.


And yes, that list at CRC2 is not so much "identical to OEM" petcocks as "petcocks that will bolt to a tank and should do the job". The directions of the gas and vacuum ports on the back often differ as well. Sometimes you just re-route the fuel and vacuum hoses, and sometimes you can remove the back and rotate it to a better position.


Stepping back a bit, a vacuum operated petcock is fundamentally a very, very simple device. I can't see why it would take advanced technology to manufacture these things. Many of us here, me included, have installed very inexpensive and perfectly adequate and functional Chinese master cylinders with no problems.


One detail I'll mention for onlookers: the bolt holes in a GS tank go through into the tank, so the bolt heads must have sealing washers. These are very often "perished", as the British say, rarely noticed or replaced, and have wrongfully condemned many an innocent petcock. The correct metal and rubber Suzuki sealing washers (part # 09168-06023 ) are fairly cheap at about $1.50 each, but I've successfully used 1/4" black nylon washers from a hardware store for many years. Or McMaster-Carr, of course: https://www.mcmaster.com/93786A125

[Gorminrider]

Tip. Fill the tank right up. I bought a cheapo that worked fine with 1/2 a tank but couldn't hold back a full one. Weak spring. That said, the latest cheapo ones seem to be getting good reviews.

[dpep]

Tip. Fill the tank right up. I bought a cheapo that worked fine with 1/2 a tank but couldn't hold back a full one. Weak spring. That said, the latest cheapo ones seem to be getting good reviews.

Good point. I think that may have been what happened with the cheapo that is on there now. I only put a gallon in it to test for leak and saw no drips after a few days so assumed it was good. pouring gas back in forth between the tank and 5 gallon gas can is going to be a royal PITA but it seems that is where this issue has gotten to.
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[Gorminrider]

dpep, it may be possible to experiment with springs.
MY cheapo (Grimly and I each bought one) had a smaller diameter spring than the OEM but I was able to find another for it that seems to work...springs can be added too.

I'm still not sure exactly on this but after a discussion on another forum-(different bike) it may be that simple stretching the spring may help...this would seem to work because distortion of springs is "linear" to forece so extending the spring"moves" the force required along that liner scale versus the length of the confined space the spring occupies...Very similar to preloading suspension..in fact inserting a spacer like one does with forks might have a similar and safer result ...the Trouble with these is that it also means more force needed to OPEN the valve..

naturally you'll want to Measure the Original FIRST, if you care to experiment..

So, the long and short of it would be, stretching the spring resists fuel pressure more but also requires more vacuum to open the valve....
This might be a helpful link? https://www.cgtk.co.uk/metalwork/calculators/spring

[Grimly]

Problem with extra force on the spring is it can't go too far, lest weak running results.
It should work, but needs figures.

[Gorminrider]

Yes.^^^it'd be good to be beyond experiment and get a better success fixing em... One wonders if the original creeps over the 35 years like old car springs. They don't include new ones in the rebuild kits. And the original lengths of the spring is unknown versus clutch springs...I admit I'm a little Obsessed but just dumping the originals in the metals bin seems a crime.

Add days later: To be plainer, if the spring pushes too hard, the vacuum won't open it properly. Symptom would be "blipping throttle works when bike feels like it's running out of gas", or any long stretch of operation where engine vacuum is low.

[alke46]

Larry, your Pringle is manually operated, correct? My issue is that I would forget to turn off a manual petcock more than half the time and regularly have gasoline in my cylinders, crankcase, and on my garage floor. Too many years with vacuum operated ones for me to unlearn. I would certainly buy oem if they were available.

Since I can buy 3 or 4 of the ebay cheapos for the price of one oem I think that is what I will do. Then just test them on the tank hoping that one of the four won't leak gas in the vacuum off positions. The one i have on there now is a cheapo that does not pass the test.
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Sorry for posting this so late, but when I installed the Pingle it has a reserve function that certainly needed to be tested.

I knew I was getting close to going to reserve so I left home knowing where a gas station was that was 40 miles from my house.
After just past 4 miles, the engine started sputtering so I switched to reserve and upon nearing the gas station, the engine died.

I was able to pull in the clutch and coast right up to the pump.

This shows the accuracy of the reserve amount -- well maybe not scientifically, but close enough for me.IMG_20200728_110119239_HDR by Larry Alkire, on Flickr

[Gorminrider]

Don't forget that some of the vacuum taps can be easily modded to be simple taps...

THIS from an earlier analysis here.

By removing the little stop tab so the lever can be straight up I have OFF. By removing the diaphragm o-ring I have ON (without needing vacuum) and still have a functioning RESERVE when in the RESERVE position. PRIME is no longer needed since vacuum is not connected. The filter screen is connected. I also added an inline filter to keep the fine rust dust from the carbs. I did leave the diaphragm spring out but you can do what you want. "

BUT doesnt work on all my petcocks... some have a hole right through the nylon plugs but it does work where there is one hole that flows into hollow nylon valve plug...(the "tab" mentioned is on the chromed cover plateiremoving it allows the tap handle to rotate 360 which in turn rotates the (nylon?) plug that directs gas...)

[oldGSfan]

Just my opinion but I would say you got lucky. In my past experiences I usually get what I pay for.
When I replaced mine on the gs1000e, I went with the pingle. Sure, more money but like I said, you get what you pay for.

That's fine, I also got unlucky with a $115 OEM one for my GS1100E that doesn't work properly, so chancing it for under $20 and having it work out for me is an OK deal. I'm not recommending, just sharing. It could be that the prime circuit on the OEM one got some grit in it or something. I need to check. Tank was super clean but you never know.

[shamer]

Good point. I think that may have been what happened with the cheapo that is on there now. I only put a gallon in it to test for leak and saw no drips after a few days so assumed it was good. pouring gas back in forth between the tank and 5 gallon gas can is going to be a royal PITA but it seems that is where this issue has gotten to.
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Well - a definitive verdict yet? Or still in the testing phase?

I'm a previous forum member going back to 2006 who only seems to to come back every few years and has to re-register each time... I have a GS850GL that I previously fixed this issue on and am now having to re-do it again about 15 years later. Looking at rebuild kits, aftermarket, etc. so I'd love to know the results of testing these eBay/Amazon replacements. I'd gladly order the K&Ls from Z1 if they're better, though!

This is a problem that seems you're never truly rid of! I will be cleaning the carbs this month to see where the issue is with float & valves, too, as this problem is like the Sith... there's always 2, a master and an apprentice. Probably gunk or bad o-ring at this point...

ew8zK1mw-sm.jpg

[rphillips]

Now having to re-do it again about 15 yrs. later. I wish they would last forever, but 15 yrs. don't seem too bad....Well we're talking GS's, guess we would expect more than 15 yrs. Oh yeah, Welcome back.

[dpep]

I am just finishing up on the last test item. It will be a few days before I can write it up and show the pics. But in general I can say they all performed satisfactorily. I would take my chances with one of these assembled Chinese petcocks over the rebuild kit route.. But I would also test it out on the the tank first. How I learned to best do that will be part of my write up.
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[93Bandit]

I am just finishing up on the last test item. It will be a few days before I can write it up and show the pics. But in general I can say they all performed satisfactorily. I would take my chances with one of these assembled Chinese petcocks over the rebuild kit route.. But I would also test it out on the the tank first. How I learned to best do that will be part of my write up.
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Interesting. I look forward to the write-up. I've been busy/lazy so I haven't rebuilt my OEM petcock yet, and it's getting worse. Every time I move the bike in my garage (without starting it) it pukes fuel from the carb overflow tubes.

Maybe I'll order a Chinese assembled unit and put the OEM and rebuild kit on the shelf for a rainy day. Sure would be quicker to to slap a new one on vs rebuilding the OEM one.

[93Bandit]

I am just finishing up on the last test item. It will be a few days before I can write it up and show the pics. But in general I can say they all performed satisfactorily. I would take my chances with one of these assembled Chinese petcocks over the rebuild kit route.. But I would also test it out on the the tank first. How I learned to best do that will be part of my write up.
...

Interesting. I look forward to the write-up. I've been busy/lazy so I haven't rebuilt my OEM petcock yet, and it's getting worse. Every time I move the bike in my garage (without starting it) it pukes fuel from the carb overflow tubes.

Maybe I'll order a Chinese assembled unit and put the OEM and rebuild kit on the shelf for a rainy day. Sure would be quicker to to slap a new one on vs rebuilding the OEM one.