'79 GS550E Petcock: Stock or Replacement?

[stumpe480]

I've been working on a '79 GS550E that was not running and thrown in as a bonus while purchasing another bike. It's been a fun project! The forums have been helpful but I can't find exactly what i'm looking for when it comes to the Petcock.

On my bike I only see RES and ON positions but the manual suggests a PRI position, I also do not see a priming screw. I just worked on the carbs so priming is necessary and I think it may be the only thing keeping the bike from turning over right now. It does appear to be a vacuum petcock. Could it be that this is not the stock petcock and a previous owner mistakenly replaced it or am I missing something?

I'm attaching a pic from prior to the start of the project. If anyone has a picture of a known stock petcock from a '79 please let me know.

[stumpe480]

Add'l Picture

Here's a shot of the petcock on its own, disassembled for cleaning.

[ChicagoBob]

It's an aftermarket replacement. The originals don't usually last 30 years, but I have one on my '78 550 that works fine:

[stumpe480]

Exactly what I was assuming. Thanks for the picture, very helpful. Like you say, originals have a tough time lasting 30 years. Now to find a proper replacement...