petcock replacement

Mabye im the only crazy one here who likes vacum petcock but mabye that is also since mine is still working just fine. Anyways there seems to be some trouble finding rebuild kits and or just new petcocks and adapter plates. No one has mention z1enterprises.com yet that where i get a lot of my stuff and they seem to have everything there.
 
Mabye im the only crazy one here who likes vacum petcock but mabye that is also since mine is still working just fine. Anyways there seems to be some trouble finding rebuild kits and or just new petcocks and adapter plates. No one has mention z1enterprises.com yet that where i get a lot of my stuff and they seem to have everything there.


I don't mind mine as long as it's working, and mine has been working just fine for the 2 years since I have owned it. Kind of a good idea actually, you can unhook the fuel line fron the carb (as long as the bike is not running) without worring about spilling gas everywhere, and you don't have to worry about a stuck float valve spilling gas all over the engine, or worse flooding the heads. But! if it starts leaking (as my buddy's did last year) . . . you will curse the day the contraption and the guy who invented it, was born.
 
Believe it or not I found this thread using the "search" function (which usually never leads me in the right direction!). This answered most of my questions about the XS400 petcocks. I'm switching over to the manual style/non-vacuum XS650 one from MikesXS. Just for anyone who may be curious, I'll post pics and give a short review. I'd rather go the XS650 petcock route just based on simplicity and looks. Not a huge fan of the chrome universal unit.
 
I have the mikes XS one. Just be warned, it fits, but you can't turn it to the reserve position without a spacer, or modifying the handle
 
I have them on both my 80 and 82 tanks and reserve works. It just don't turn all the way up but fuel will still flow.
 
I was wondering if it would work in that 3/4 position. Didn't want to test it. I just ground off a mm on the back and it goes all the way up now
 
Yep, no need to mod them. Flow is the same. With such a small petcock the "off" spot is very small. The only time I have ever needed to use that setting is when I drain the tanks for winter.
 
Hi

Sorry old post revival.

1980 XS400 SG5 (special or custom in the UK) Rebuilt petcock but still leaking. I added a stronger spring behind the diaphragm but it still leaks when in the on position.

I was going to convert to manual as I have seen on an XS750 site but I'm a bit concerned about the amount of metal that needs to be removed in proximity to the outer casing. Too close for my liking.

That leaves me with the petcock from Mikes XS as described here, with the 46mm centres. However there is no filter fitted over the main and reserve feed tubes. Has anyone tried fitting the ones that Mikes XS supply or is it possible to utilise the ones fitted to the original XS 400 petcock??

Cheers

Fent
 
The mikesxs ones come with screens that fit over the tubes. You can also buy replacement ones for them also.
 

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That's perfect Chris thanks for that.
The mikesxs ones come with screens that fit over the tubes. You can also buy replacement ones for them also.
I have also rebuilt xs400 petcock with all new parts including a new diaphragm and have found the gas to run in all 3 positions and that gas comes out of the drain hole when it's been parked up after a ride out. Any ideas what the problem is please thanks in advance
 
Could be the o-ring on the diaphragm. I have found a lot of the rebuild kits don't use well made or fitting parts. Ditch it and use a manual one!! I have five bikes and all have manual. Never looking back again.
 
I have posted that doubling up on orings, specifically a small one to push the bigger one out, will solve that problem. When I rebuilt mine last, I found out that Yamaha like anyone one else used what was on the market, and the quality control was so bad, that the fix then was a soft spongy oring, that would compensate. Now the current release of that oring, it isn't as thick as the oringinal. Which is why the doubled up oring solution worked for me. The poor quality control that I found out about on a Maxim website, had actually thoroughly documented the problem. I found that thread.
http://www.xs400.com/threads/how-to-rebuild-your-leaky-or-starving-petcock.8033/page-2

http://www.maxim-x.com/petcock.html If you check out this website, the diagram of the oring, all I am suggesting (by looking at this page) is that smaller (4mm viton) oring, can push the bigger oring, up, and out, where it will mate with the conical barrier. regardless of the flawed machining which is figured early in that webpage. I Figure that was 2013, so I am into our 3rd biking season.
 
I need help with my petcock. I bought a replacement on eBay and the holes don't match up with the holes on the tank.

My question is how do those plates off parts and more work? What does it take to make it all work?
 
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