Petcock question...

[Force10]

Sooo... I have a question.
I have a vacuum operated petcock for my 82 gs850 that, when Steve pulled it apart, had no o-ring. I found a 2mm i.d. x 4mm o.d. o-ring that *appears* to function. It is made of Buna-n, not the best but *should* work for now ...
My question is, though the diaphram looks decent, when I do a bench vacuum test (put it up to my mouth and apply vacuum...) it doesn't seem to hold a vacuum. Is this typical, or will it cause gasoline to be drawn into the #2 carb?

[Nessism]

It needs to hold vacuum or the petcock won't work properly, but it will only dump fuel down the vacuum line if the diaphragm has a hole through.

[Kapoor]

I did the same bench test not too long ago and to my knowledge when i sucked in I could tell that it was shut. So it does sound like you either have a hole in the diaphragm or like my petcock there's 30 years of junk built up around where the slider slides under the diaphragm. I took mine apart inspected the diaphragm and scraped away all of the junk and it's good as new again!

[Adler]

I wonder if a simple redneck fix for something like this would work... Like, for example, tape on the diaphram? maybe a rubber cement glue?

[tejasmud]

I wonder if a simple redneck fix for something like this would work... Like, for example, tape on the diaphram? maybe a rubber cement glue?

It only will work on a 1979 GS550L petcock.

[GS ace]

Bad Diaphragm

A leaky petcock diaphragm can easily let fuel seep into the crankcase. It happened to my 1100E.

[nickr234]

I wonder if a simple redneck fix for something like this would work... Like, for example, tape on the diaphram? maybe a rubber cement glue?

the only "redneck" fix i would even consider trying is cardboard, but rebuild kit arn't they best thing in the world either.... i would say spend the 80 bucks or so and get a OEM replacment or you can check for an aftermarket one for about 50 bucks

[wera racer]

I can't remember exactly how I did it because it was a couple years ago and it's not the legs that go first, but I converted my stock petcock to not use the vacuum line by filling one of the internal ports with the gas tank sealer stuff you can get at an auto parts store. It effectively made the "prime" setting or whatever it's called "off." So now I have on/off/reserve and no "prime." Works great. Don't forget to plug the number 3 carb vacuum when you remove the hose to the petcock.

[Force10]

Well after trying to run the petcock with the new O-ring, it didn't work. I'm not too surprised, but I figured it was worth a try.

So a new petcock will be installed. Soon hopefully, I want to get this thing driving!!!

[nickr234]

winter is comin

Well after trying to run the petcock with the new O-ring, it didn't work. I'm not too surprised, but I figured it was worth a try.

So a new petcock will be installed. Soon hopefully, I want to get this thing driving!!!

winter is comming here in South Dakota... and i need my vavles shimmed and i am rejetting it right now... i can't w8 either

[tkent02]

Z1 will ship it immediately, two days later you will have it.

[Force10]

winter is comming here in South Dakota... and i need my vavles shimmed and i am rejetting it right now... i can't w8 either

I grew up near Scottsbluff, NE so I know what those winters can be like!
Good luck on the bike!