New petcock diaphram waste of time

[Fat Don]

I had issues with my petcock rebuild kit as well. I could have bought a pingle but for me the whole point of this bike is to fix things myself and not buy new parts to fix an old bike if it could be helped at all. After talking to Gustov and polishing up the tapered hole the post and o-ring sit in it still dribbled. I ended up sanding down the spacer that is sandwiched between the two diaphram layers. I sanded it down about 1/3 original thickness with a right angle grinder. That allowed the post o-ring to seat itself completely and no more leaks.

[rthor]

Due to lack of time I haven't got around to taking on the project yet. I'll be giving it another go on the weekend.
Don, I was looking at the diaphram and I can't see how I would be able the take out the middle spacer. Any suggestions?

[Fat Don]

Don, I was looking at the diaphram and I can't see how I would be able the take out the middle spacer. Any suggestions?

with my petcock the diaphram has a plastic spacer that fits in between the two "sheets" of the diaphram. to take it out just hold the spacer on the edges and push the post through a hole in the spacer. you cant see this hole but it's there. your rebuild kit should have come with a new diaphram and that diaphram needs to be used with that spacer if you had one in the original set-up. by the way, there is a good write up on a petcock rebuild with assembly pictures on BassCliffs web page, do a search for petcock rebuild and you should see it.

[feelergaugephil]

can always go with a pingel petcock.

Manual. On/off. Just remember to turn it off.

I have gone back to a sgp (oem) on the petcock, but any trouble, and pingel it is....

+100.............

[SqDancerLynn1]

Lots of problems with the old petcocks & trying to rebuild them which is why A replacement is sugested. Pingle also makes a vacuum operated petcock if you want to spend the $$$$

[rthor]

Don,
My dumb...
I thought the spacer you were talking about was the middle metal spacer on the diaphram itself. Now I see what you are talking about...you are referring to the plastic spacer that is placed between the diphram rubbers. I'll take a few mm off that and give it a try (on the week-end).
I'll let you know how it worked out.
Thanks for the tech support.

[Skateguy50]

Ah, the good old days...

Remember to turn on the gas
Remember to turn on the lights
Remember to put up the kickstand
No gas gauge
No neutral light
No gear indicators
Use your arm to signal

My-o-my, how did we manage to ride at all....

Minus the hand signals that sounds just like my wife's rebel, she has to turn the gas on / off, no rpms, no gear indicator, and well most the time the speed doesnt read... I should fix that cable.

[81GS]

I just bought a rebuild kit from Z-1 and rebuilt my pepcock this last weekend. Works fine now. No problems and the bike runs smoother now. Just followed the rebuild instructions found on this site.

Bob

[Matchless]

As said by earlier posters your new diaphram will not seal properly if the small o-ring does not seal properly or that seating part of the petcock is worn. Also look at slightly stretching the spring for the diaphram as it may have lost some of its tension over the years.
Sometimes a slightly thicker o-ring from an engineering supplier can also solve the problem.

Just a last comment the holes in the one corner of the diaphram must line up with the spacer and the membrane and the body of the petcock - but you probably know that.

[rthor]

Ok, things to go over on the second attempt...

-check for blemishes/imperfections in the valve body
-polish the surface of the valve body with a tapered mandrel
-take a couple of mm off the plastic spacer
-stretch spring slightly
-try slightly larger o-ring

Thanks for all the suggestions guys. I wouldn't have likely considered any of these things. Your experience on this subject is most appreciated. I'll post the results sometime this weekend.

[reddirtrider]

All dirt bikes (that I know of) use a manual setup like the Pingle. I admit quite a few street riders are not used to them, but they work very well but only if you remember to turn them off.

If you can remeber to take the key out of the ignition (somthing that isn't required on dirt bikes, you can surely to reach down and turn off the gas.

Just a thought.

[gubzsuzuki]

I just rebuilt mine the other day and it works great. It seems like it is a hit or miss kind of thing reading this thread. Guess I got lucky. Good luck in whatever you decide/ pingel or rebuild.

[Nessism]

One thing to keep in mind is that there are three different types of OE petcock. Pre 1980 with the large lever, the no lever 1980 petcock, and the 1981 and onward small lever petcock. The 1980 and later style use an O-ring on the diaphragm nipple to seal off fuel flow. The O-ring can dry out or the inside of the petcock body can corrode which will upset the seal. I've also seen some later type petcocks where the tapered plastic barrel gets scored up and binds in the petcock body. My opinion is that rebuilding the petcock is reasonable as long as the basic parts are in good shape - replacing the O-ring and/or diaphragm should fix it up. Switching to an expensive Pringle seems silly to me and completely unnecessary.

[Griffin]

One of the first things on my "to do" list when reviving an old bike is the petcock, whether it seems to be working ok or not. I've rebuilt petcocks and I've replaced them. Obviously, replacing with a new one works every time. I've had mixed results with rebuilding, it's worked wonderfully twice, was a disaster once.

The one time it didn't work was on a Yamaha XS 1100. This bike has two petcocks, and they are only available from Yamaha dealers for about $90 each Faced with this, and one petcock seemed fine, I tried a rebuild kit for the one that leaked.

The kit was the same brand as the others I'd used before (one Kawasaki, one Yamaha). This particular one seemed to fit ok, but after I installed and tested it, it leaked. Upon disassembly and inspection, I discovered that the rubber parts were swollen and deformed, evidently from reacting to the gasoline. I tossed the pieces, bit the bullet, and bought a new petcock from Yamaha.

I think that this is relevant to the aftermarket gasket thread going on right now on this forum. Evidently (at least on the XS 1100 kit), the supplier changed rubber formulas, and it wasn't chemically compatible with gasoline (kind of important on a fuel petcock!), whereas the earlier ones I had purchased were.

I guess the moral of the story with rebuild kits is you spends your money, you takes your chances.

[trippivot]

I'm sure I'm not the only one to have experienced this problem, but try as I might, that new petcock diaphram was not going to seal. With the new part in place and all tightened down, gas would keep trickling out the spigott. I eventually gave up on it and put the old one back.
Has anyone out there had success with replacing the diapram? Is there something I have to do to make it work, or should I just accept the fact that I need to buy a new OEM petcock complete?

you need to polish the metal due to porosity red 3M or green 3M works great.
rough surfaces won't seal to new rubber unless you smooth them over.