Modified Vacuum Petcock Blues.

[natemoen]

Those are some super clean petcocks Jamie! Hopefully tod doesn't manage to break them somehow...

[Jamie]

Jamie, those are pretty much if not exactly the same petcocks as used on the Special models. They are not, however, vacuum petcocks.

The Standards use a petcock that has a similar vacuum operated daphram to the one in the octy. In esence, they have tow octy valves, one on each side. Those are the vacuum petcocks.

HERE is the thread I put together on rebuilding the petcocks and the Octy. HTH.

Don,
Sorry, mis-spoke, you are correct. That damn Octy, just mentioning it and thinking vacuum. Geez, actually, mine works great, I'm sure it wont' now that I said something.

[patk12345]

So, here is a picture of the petcocks on my bike. You'll notice a small scuff on the word "FUEL" which happened when I was doing the dremel mod to create an "OFF" position.





This next photo is the tube I was talking about, it comes off the right side of the petcock, and was melted shut. Any ideas as to what this is doing?

[patk12345]

Sorry, can't get these pics to show up. I'll try again.

[patk12345]

This will have to do for now...
So, here is a picture of the petcocks on my bike. You'll notice a small scuff on the word "FUEL" which happened when I was doing the dremel mod to create an "OFF" position.

https://picasaweb.google.com/lh/phot...eat=directlink

This next photo is the tube I was talking about, it comes off the right side of the petcock, and was melted shut. Any ideas as to what this is doing?

https://picasaweb.google.com/lh/phot...eat=directlink

[jwhughes3]

patk12345 - I use picasaweb too

Sorry, can't get these pics to show up. I'll try again.

In Picasaweb - on right side click on "Link to this photo"

Below that will display:

Link (and a box with hypertext) [ignore this box]

Embed image (and a box) [pay attention to this box but not yet!]

Select size (and a box) [FIRST select the size you want - 400 or 640 is best]
Hide album link
Image only (no link) [SECOND - click here and the "Hide album link goes grey"]

NOW go back to the "Embed Image" box and highlight the link text that appears there.

In your post, press the "Insert Image" icon that looks like a postcard.
When the box appears to enter the URL of you image, the http:// is already highlighted - you can then right click the mouse and PASTE.

Now try and PREVIEW you post and you should see the pic inside.

John

[jwhughes3]

The melted tube

Is the vacuum tube that should be hooked to a vacuum source (like the nipples on the manifold to carb boots - you can hook to these because this vacuum is not open and will not affect the running like an open vacuum leak would.

Without that tube going to vacuum, you standard petcocks will not auto shut off - they might not have been doing that anyway or the prior owner didn't know what that nipple was for so he just blocked it off.


John

[Ken Talbot]

Without that tube being connected to a vacuum nipple, your fuel diaphragm willnot open, which means it should only flow fuel in the prime position. If it flows in either on or reserve, something has been altered inside, which can cause you all kinds of grief.

[jwhughes3]

sorry - ken is right - i am backwards

with the vacuum - which only makes sense if you think about it -

how can you have vacuum without the engine running?

John

[cywelchjr]

So is the tank a special teardrop tank or the standard kinda square tank with the knee indents? Those are certainly standard petcocks which it seems have been modified to flow all the time, and those have likely been plugged because the diaphragm is leaking and if those are taken off gas comes out of them . I've seen them do that before. You could probably fix those and have the vacuum function back, or just leave them alone and remember to shut them off when the turn off the bike, your choice. The kits can be had from georgefix on ebay, just make sure to get STANDARD petcock kits, not specials, cause their not the same. Then again there is a tech tip in the tech tips section on how to solder up one of the grooves in the back of the handle of the petcock and end up with a modified petcock that is no longer a vacuum unit and then you don't have to bother, and then prime would be off, on would be on, res would be reserve, and the extra off would be another off .

[patk12345]

@John
Thanks for the advice. I'm not great with HTML as it is, but that was ridiculous. I wasted half an hour trying to get two pictures up. You think Google would have a smoother set up.

[patk12345]

@Cy
It is the squared standard style tank. I haven't messed around with the petcocks too much. In the past I always pumped out the gas before pulling it of for any work. I need to put it on the bench, put a bucket underneath it and figure it out for sure. The previous owner had the entire bike rebuilt by a custom in Kansas long before I got it, so there are little things like this all over the bike. Without this forum I would've had put the poor thing down long ago.