Yet another petcock question

[Steve]

That is the best written explanation of the design I have ever seen. Thanks, Steve.

You are welcome.

Anything else you need explained?

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[Big T]

Don't know if this helps, as the vacuum port on my '83 GS1100E is on carb #2, and I'm pretty certain, your carbs are different than mine, but I grabbed a photo anyway.
I was thinking it should be located on yours, somewhat the same way, and might point you in the right direction.
Not using it on my bike, (see Pingel), and it is under the little yellow cap, near the center of the photo.
(Guess I could've taken the cap off for the photo )

VM carbs are completely different. The vacuum port is brass, on the side of carb #3

[tom203]

You are welcome.

Anything else you need explained?

.

Just tell them to get a new petcock and stop monkeying with a tired old one.

[Baatfam]

VM carbs are completely different. The vacuum port is brass, on the side of carb #3

Well not completely different....mine is also brass...under that yellow cap...

[BoardBandit]

Well after taking the petcock apart again and examining it given Steve's explanation, it appears the "tab" on the plastic block has been ground off and any "flat, curved spring" is missing. Thank you all again. Most helpful explanation.

[headsbikesmopars]

The 8 valve engines must be different than the 16 valve engines . All of my 16 valve GS's have the Vacuum nipple on #2 carb .

[Steve]

The 8 valve engines must be different than the 16 valve engines . All of my 16 valve GS's have the Vacuum nipple on #2 carb .

It's not 8-valve vs. 16-valve engines. It's VM-series carbs vs. BS-series carbs, which appeared on most bikes* in the 1980 model year.

All of the 16-valve engines happen to have BS-series carbs.

*Trivia detail: the two-cylinder bikes before 1980 also had BS-series carbs.

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[bwringer]

Just tell them to get a new petcock and stop monkeying with a tired old one.

Yeah, pretty much. Disassembling a petcock is an utterly useless action unless you just want to see how it works.

Many have tried to save an old petcock, all have failed. Untold volumes of gasoline and time have been spilled and wasted on this hopeless endeavor.

Replace with OEM or OEM equivalent and forget about petcock troubles for another 30 years.

Or look at it this way: it's a crucial valve controlling an incredibly flammable fluid a few inches from your crotch. Is this really the place to skimp?