#2 cylinder always rich and fouled

[Rijko]

I have seen several rebuild kits that have an o-ring on the diaphragm that's a little bit smaller than the original.
And the diaphragm rod almost half a millimeter shorter than original.
So the o-ring never seats nicely, and gas flow does not shut off completely.
An o-ring slightly larger solved that for me.

But a buddy recently solved that by placing 2 small rings in the recess behind the spring, and it held up to now.
( stretching the spring was not sufficient )
Might be worth a try ?

[Bammer07]

Newbie question. I too have a rich fouled cylinder #2 plug (as well as some other issues). Replacement petcocks obviously must be vacuum style, but are there other criteria they need to meet in order to be compatible?

[Rich82GS750TZ]

Hi Bammer07, welcome. It would be appreciated if you’d make an introductory post in the GS Owners forum.

To answer your questions:
Nothing obvious about the petcocks. Some folks replace original vacuum types with a simple but expensive fuel tap made by Pingel. They are typically simple On/Off design, probably requiring an adaptor plate that match the threaded hole spacing on the bottom of your particular tank. Because they are simple ON/OFF, you must remember to turn it On before you start the bike. More importantly, you ABSOLUTELY MUST remember to turn it OFF after you park the bike. Failure to do so will more than likely result in an empty fuel tank, and engine full of gas mixed with the oil, and a huge mess. Also, if you use this type of non-vacuum petcock, you must plug the vacuum port on the carb body. (Front of # 2 on CVs, or back of # 3 for VMs).

The replacement OEM-style petcocks at georgefixs that I linked above are year/model specific.
And I think but am not positive, that they only sell for GS models ‘80 and newer. Different years and models have varying threaded hole spacing to line up with the holes on the bottom of your particular year/model tank. Be certain of the year/model and hole spacing before you buy any petcock.