Petcock Question--What is this hole?

I wanted an optional larger gas tank for my '78 KZ1000 LTD to use for longer rides. So I found one on EBay for cheap that bolts right on. It didn't come with a petcock, but had the bolt-on style holes.

I later bought the petcock seperately from the same seller of the tank (I assume this petcock is the original one from this tank). It is the vacuum style petcock--which I prefer, as long as it doesn't leak.

There are three hose nipples on it. There is one near the top, which I assume is the vacuum connection. Then there are two at the bottom--one pointing straight down, and the other horizontal. I assume these are the dual fuel outlets.

Directly below the horizontal nipple, there is a threaded hole (M6 threads) pointing straight down, which connects with the passage that exits through the horizontal nipple--meaning that if I hook this thing up, fuel is going to leak from this hole.

My question is, what is this hole for? I assume I can just get a very short M6 bolt and plug it up, but what is its purpose? Anyone know what I am talking about?

Post edited by: Skyman, at: 2007/03/01 17:53

Representative 78 vacuum petcock?

If it's what I think you are talking about, there is a drain on the bottom of the petcock that a bolt goes into. The $12.29 #27 bolt in the picture. . .
and don't forget, the non-available anymore washer.

2 thought come to mind...a sludge-drain,OR...some type of bleeder screw??(to prime the system)...maybe??:huh:

KaZooCruiser wrote:

Representative 78 vacuum petcock?

If it's what I think you are talking about, there is a drain on the bottom of the petcock that a bolt goes into. The $12.29 #27 bolt in the picture. . .
and don't forget, the non-available anymore washer.

Yep, I think that's it. I'm going to run right out and get me one of those fancy $12.29 plugs right now!

Maybe I can find the washer on Ebay! :whistle: