fuelcock/petcock replacement

[dpep]

Once all of the petcocks arrived and were out of their boxes the first thing that struck me was how identical they were in appearance. Even the boxes and sealed plastic bags they arrived in were identical. This was the same petcock being sold by three different vendors. I was careful to keep each of them in or very near their boxes which I had marked. Otherwise I would not have been able to tell them apart.



The included gasket was just a tad oversized but could be fitted into the grooves. The gaskets for all three were off in exactly the same place by exactly the same amount which adds to the evidence they all came from the same place.



Though I am too lazy to research it I suspect there may be only one Chinese company churning these things out. If there is more than one they all work with the same specs and tooling. The only observable differences were in the resistance to moving the lever. One was initially a little easier to move but after hitting them all with some penetrating oil and working the lever back and forth a few times that difference became minimal.

The most expensive of the three included a hokey pair of vinyl gloves in the box. It was the one that was initially easier to turn but it was also the only one that had a noticeable machine flaw. There was a thin tab of metal partially covering one of the bolt holes. It was easily flicked out with a screw driver, but it dispelled any curiosity as to whether the higher price bought any additional quality control.



Results

They all worked. During the three test sessions not a drop of gasoline hit my catch bucket. If I were to again need to replace a petcock I would definitely take one of these finished assemblies over the rebuild route. They are cheap enough you could buy two and test as I did. The odds that both would be bad have to be tiny. More likely you would just have a spare for possible future use.

And you can buy cheap. The only thing you MAY get by paying more is faster delivery time. The cheapest of these three performed as well as the most expensive. But it was sent USPS and took three or four more days to arrive than the other two which were Amazon delivered.


For me a bonus from this testing exercise was learning about this new (to me) style trick siphon hose. All you do is jiggle it down in the liquid for a few seconds and it starts flowing. No pumps, no drills, no gasoline in the mouth. Now that is progress.



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[dpep]

Vacuum petcock test


I ordered through Amazon Prime (no shipping charge) three vacuum petcocks for my '81 GS850G. Each was from a different vendor and had a different price. I ordered them all from Amazon so shipping cost could be omitted from the comparison. The price you see in the pictures is as listed on the site before taxes (7% in Florida). I could have used ebay or most any motorcycle parts vendor and gotten the exact same item.

First I will familiarize you with the state of the art testing facility utilized in making these comparisons.




Siphon hose, drain hose, 10mm socket & wrench, portable light



For each petcock I siphoned all of the gas in a nearly full five gallon can into the gas tank. I then put a bucket under the petcock. I put it in the ON position for 12 hours after which I put in the RESERVE position for another 12 hours.

After that I connected a hose from the petcock back into the five gallon can and switched to PRIME to flow the gas back into the can. When the tank is almost empty it helps to tilt and shake it to get as much of the gas as possible through the petcock and out of the tank. That will help keep and remaining fuel from leaking out of the top when you turn the tank upside down to swap to the next petcock.



...Continued

[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.

[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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[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.

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...

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[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.

[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...)

[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]

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.

[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]

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

[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.
...

[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.