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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.
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.
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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 FlickrDon't forget that some of the vacuum taps can be easily modded to be simple taps...
THIS from an earlier analysis here.
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...)
THIS from an earlier analysis here.
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...)
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.
G
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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...
dpep
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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
Forum Mentor
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
Forum Mentor
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.
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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
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
dpep
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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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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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93Bandit
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Thank you for the excellent testing, Sir! That looks like the check ball style siphon, those things are great!
I only have one question about the valves: will a vacuum source affect how these valves seal? I wonder if they only sealed because you didn't apply vacuum to them yet?
I only have one question about the valves: will a vacuum source affect how these valves seal? I wonder if they only sealed because you didn't apply vacuum to them yet?
Good-thought! it occurs to me a vacuum test comparison could be done with a large syringe and a hose to suit...the amount of vacuum needed for flow is gauged by the pull required...
as to "single-factory", personally, I rely upon it across Amazon, ebay, ali-express..if it looks the same- it is the same (usually the same picture is used) so beyond price and shipping I would recommend perusal of feedback- I pay a little more for the best feedback as a ratio per seller's number of sales...
Vacuum shouldn't have anything to do with the valve sealing back, vacuum pulls the valve open against the spring pressure & the lack of vacuum only releases the spring so it can reseal the valve. Takes very little vacuum to open valve, put on a piece of hose on the vacuum nipple & gently suck on it with your mouth, you can actually feel the valve open & close. No gas in mouth unless there is a hole in diaphragm. Amazing how little vacuum it takes.
^^^but that is the rub- too weak a spring(too easy to open) means fuel pressure can do the same thing. Fuel pressure in a gravity feed varies while some some petcocks are built for fuel pumps where pressure is consistent. One may work for the other but my experience suggests they may not
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93Bandit
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I understand the operation. My concern is if it does infact reseal properly after Vacuum has been applied and then removed. Simply put, will these valves start leaking after a dynamic test? The static test performed is very valuable information and has convinced me to try one. I just wonder about the results of a dynamic test?
After my failed attempt at converting the valve from my '81 550T, add me to the list of "just ordered a $20 petcock from AMZN, let's see how it works"
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One thing I discovered when mounting on the bike is there a potential routing issue for the fuel line. The fuel nozzle on the oem points to the front into open space. On these the nozzle points to the inside of the bike and on the 850 the opening is less than an inch from the side of the airbox. I first tried routing the line by the most direct route turning it toward the front. Because of the tight space however that created a crimp in the bend.
I ended up routing the line from the carbs over the top of the airbox and down to the petcock nozzle which was still a tight fit but straight enough that there was no crimping.
It is not a deal breaker. Just keep in mind that you may have to do a little work around. I also thought about using some thick walled marine hose that I had in the garage for the line. It is stiff to work with, but it is not going to crimp.
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I ended up routing the line from the carbs over the top of the airbox and down to the petcock nozzle which was still a tight fit but straight enough that there was no crimping.
It is not a deal breaker. Just keep in mind that you may have to do a little work around. I also thought about using some thick walled marine hose that I had in the garage for the line. It is stiff to work with, but it is not going to crimp.
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