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Gas leak even after petcock rebuild - suggestions?

  • Thread starter Thread starter rcp
  • Start date Start date
R

rcp

Guest
I'm rebuilding an '81 GS1000G that I bought in boxes. I'm getting pretty close to the first test ride, having surmounted missing axle spacers, lack of shocks, missing exhaust, snapped-off bolt extractors and numberous other obstacles.

Last night, I removed, rebuilt and replaced the petcock as it was leaking a little in the ON position and a lot in the RES position. I replaced all the rubber gaskets, and the diaphragm with new bits from a kit. The spring seemed fine, and none of the passage ways seemed blocked.

When I tested it out by blowing though the gas passages, in the PRI, RES and ON positions, it was fine with vaccum applied (good flow). However with vaccum removed, the PRI and ON positions could be blown through, (albeit with resistance) with a bit more air pressure. I disassembled it again and looked at it. I believe I've got the plastic bit in correctly (flat side towards petcock lever, concave side towards vacuum source) and the diaphram lined up properly (hole in diaphram lined up with hole on lever side). I couldn't find anything that needed improving, so closed it up and tested it, with the same result. I guessed that maybe it didn't need to hold much pressure and so I bolted it up to test it with some gas in the tank.

Sigh. It leaks.

Any suggestions on what I might have missed? Do the seals need to swell? Or do I just need to pull it off and go through it again, and give it another, uh, blow job, until it seems right?

- Richard
 
I added a second petcock to my bike. The stock petcock was letting gas seap into the crankcase 24/7, no matter what position the petcock was in.
The vacuum line that runs to from the stock petcock to the carb will need to be plugged. Then add a second petcock behind the stocker. A 90 degree petcock is what I used. Now I can be sure the motor is not getting sabotaged by fuel in the oil because I can be sure that the petcock is not leaking.
The stock vacuum operated petcock is junk. It can leak gas into the motor and you won't necessarily know about it right away. The gas acts as a solvent, not as a lubricant, and it messes stuff up.
 
Pingle. Do a search on this site in the Technical section. You will learn all you need to know. I posted where to buy them cheap too. Suzuki Petcocks are CR4P.
patrick
 
pull it off and go through it again. sounds like you may have some dirt in the vacume shut off. or a bad gasket.
 
whodatpat said:
Pingle. Do a search on this site in the Technical section. You will learn all you need to know. I posted where to buy them cheap too. Suzuki Petcocks are CR4P.
patrick
Click to expand...

Definately. Go with the Pingle. Looks good, works great, once you get in the habit of using it. Absolutely positively works correctly. No more fuel starvation or worries about stuck float needles. No more rebuilding or hassles with vacuum lines or diaphragms. Keep It Simple....
 
Suzuki Petcocks are CR4P.
Click to expand...

I disagree. One of my bikes has a Pingel and it is a piece of garbage. Poor design and bad quality. Lots of money for such a simplistic and primative design. Stick with Suzuki, something went wrong with the rebuild.
 
I read this in the forum a while ago and pasted it into my notes, i cant remember who orginaly posted it , hope they dont mind me reposting it.

I had a badly leaking petcock on my 1978 GS1000E and decided to do a rebuild. The valve was dripping fuel all down the side of the machine and must have been doing it for quite a while judging by the stains. The previous owner's neglect was sickening.

After ordering the standard rebuild kit from a source on eBay, I cleaned up my unit, threw in the new diaphragm, o-rings and such and put everything back together. Threw it back on the tank and started filling the thing with gasoline, only to discover that fuel was flowing out of the valve with the engine off. I took the thing apart and reassmbled it several times and was quite at a loss as to why it should not function as designed.

Of course, I referred to the tech info section here on the GSR and found this to be a common problem and a continual source of frustration for many otherwise happy GS owners. Most, if not all of the leaky petcock problems were solved with a new Pringel valve and I thought about that as an option for a while.

Being an Engineer, I resolved to find the answer to this problem, that was my quest. After some measuring and experimentation, I discovered that the o-ring at the tip of the plunger that actually blocks the fuel flow was too small!!! This was the o-ring that came in the rebuild kit.

I went to the local hardware store and got the next size up in o-rings which increased the O.D. a bit as well as the I.D. the thing sealed perfectly! It sits in the groove of the plunger a bit loosely as compared to the o-ring that came in the kit but, this was much better from a functionality stand point. Please bare in mind that the difference in size was almost imperceptible, perhaps .5mm or less. I also stretched the spring about a 1/2"-1" to get more tension on the vacuum side of the diaphragm in order to get a real good seal. I tested the whole assembled unit for proper flow at about 5-10psi and was very pleased with the result.

I believe that the stock petcock on a GS1000 is the safest and most convenient form of fuel flow control and was very happy to discover that I would not have to replace it with an expensive after-market unit. It is a simply designed, very serviceable device and there is no reason that it should not function perfectly if the correct replacement parts are used.
I believe that the o-rings in the rebuild kits are the wrong size and this leads to great confusion and frustration.
 
Petcock problem produces possible prescription

Petcock problem produces possible prescription

deano said:
I read this in the forum a while ago: [snip]
I believe that the o-rings in the rebuild kits are the wrong size and this leads to great confusion and frustration.
Click to expand...

That's a reasonable explanation. I should be able to rescue the original o-ring from the trash and compare them, although that's not a definitive test, as it leaked too. I see about locating the just-a-hair-larger one at the hardware store.

I looked at the Pingle petcocks, but their price is comparable to what I just paid for a whole NOS exhaust system! It would be far more cost efficient to just add an inexpensive inline fuel cut-off switch after the leaking petcock.

Thank for all your suggestions. I'll update you on my results.

- Richard
 
I paid $52 for my Pingle. It's well made and works well IMHO, and I'm pretty familiar with valves of varying sorts. I'm referring to the simple cutoff valve version, I have no experience with their vacuum version, I don't want a vacuum operated valve.

I'm having difficulty understanding how the stock Suzuki valve could be considered better than the Pingle. My stock valve was pathetic. While everyone is certainly entitled to their opinion, I think when it comes to the Pingle vs. stock valves, the Pingle has been the clear choice for most people on this forum. Some people certainly may have had bad experiences, my experience with the Pingle is favorable though.
 
My experience is the opposite. Of the two dozen + GS's I have worked on
(some with original petcocks, some with rebuilt petcocks), every one of them has leaked, even freshly rebuilt ones. I have never seen a leaking Pingle valve. I have had a Pingle on both of my bikes for years. They have never leaked. A Pingle is a lot less expensive than a new Stock petcock every other day.

Earl



Jethro said:
Suzuki Petcocks are CR4P.
Click to expand...

I disagree. One of my bikes has a Pingel and it is a piece of garbage. Poor design and bad quality. Lots of money for such a simplistic and primative design. Stick with Suzuki, something went wrong with the rebuild.
Click to expand...
 
Ditto on the Pingle. Works beautifully, no nonsense. High flow rate to boot.

Jeff
 
Haven't used the pingle, but my new OEM petcock has been great. It was the first thing I did on the bike.
 
I still have the original petcock on my 78 Gs1000. I have cleaned it once ot twice, no rebuild kit necessary.
 
I guess there are always exceptions. :-) Apparently, I have the only GS1150EF ever built that does not vibrate and you have the only OEM petcock ever built that does not leak. :-) :-)

Earl


saaz said:
I still have the original petcock on my 78 Gs1000. I have cleaned it once ot twice, no rebuil
d kit necessary.
Click to expand...
 
Hey Earl, Let's swap. I'll swap both of my non-leaking, GS 1150 petcocks, one rebuilt the other not been rebuilt, for a non vibrating 1150 engine. I'll even throw in the ones from my GS 1100 & my wifeeee's GS 550, neither of them leak either. My personal prefrence is definitely OEM. Guess I'm just too lazy to be turning the fuel off & on all the time, like we had to do back in the early 70's,
 
Hmmm, sounds like a deal I cant turn down. :-) It funny, I was out for a ride Wednesday afternoon and happened to note that at 95-100 mph, my mirrors are absolutely motionless. Exactly the same as they are when the bike is sitting on the centerstand in the garage not running. :-)

Earl


rphillips said:
Hey Earl, Let's swap. I'll swap both of my non-leaking, GS 1150 petcocks, one rebuilt the other not been rebuilt, for a non vibrating 1150 engine. I'll even throw in the ones from my GS 1100 & my wifeeee's GS 550, neither of them leak either. My personal prefrence is definitely OEM. Guess I'm just too lazy to be turning the fuel off & on all the time, like we had to do back in the early 70's,
Click to expand...
 
earlfor said:
I guess there are always exceptions. :-) Apparently, I have the only GS1150EF ever built that does not vibrate and you have the only OEM petcock ever built that does not leak. :-) :-)

Earl


saaz said:
I still have the original petcock on my 78 Gs1000. I have cleaned it once ot twice, no rebuil
d kit necessary.
Click to expand...
Click to expand...

Looks like the only fuel petcock complaints come from those who unfortunately have leaky ones. Makes sense I guess. Anyway my 79 petcock has never been rebuilt and also doesn't leak. My previous one didn't leak either. If mine starts to leak next week I guess I'll have blame Earl. :lol:
 
My bike is not too bad vibe wise when cruising. Accelerate past 6500 hard and the mirrors get a bit buzzy just when you probably need them most....but I am usually looking ahead so it does not matter :)
 
Thats for sure. If I'm in 5th and accelerating hard from 6500, there is damn little that will be coming up on me from behind. :-)

Earl



saaz said:
My bike is not too bad vibe wise when cruising. Accelerate past 6500 hard and the mirrors get a bit buzzy just when you probably need them most....but I am usually looking ahead so it does not matter :)
Click to expand...
 
There is a rod with about a half loop of spring built into it that puts pressure on the diaphram in the prime position to allow fuel to flow. Try varying the length of that rod to cure your problem.
 
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