Weak flow from petcocks

[bgrubb7]

'81 H. Been in barn for 15 years.

Took the petcocks apart and cleaned. The seals were a little hard, but no cracks and appeared salvageable. I soaked them in PB Blaster for half a day, which brought them back to life. Blew compressed air through all the passages, and all is clear. Reassembled the Petcocks. I can suck in on the vacuum port and diaphragm seems to be working and holding open when on vacuum.

Petcocks back on tank and gas in tank. No Leaks! But poor flow. Gas trickles out. Actually more of a drip. Gas should be pouring out, right? Same whether on Prime, or whether they are ON, and vacuum is applied. Took back apart thinking that I put them back together wrong, but everything looks OK. Passages are still clear after disassembling.

How easy should the valve be to turn (between Prime, On, Res.) Mine is quite tight. I never bent the spring to begin with, so I don't think that to much spring is the issue. Maybe the PB caused the seals to swell too much, but I would think that they've had ample time to dry out and go back to normal. Obviously I don't have a new set to compare to.

Any recommendations? Everyone seems to be out of stock on the rebuild kits. I'll just buy new aftermarket ones & adapter plates before I pay 60+ on fleabay for the rebuild kits. Hoping to salvage what I have.

[CatatonicBug]

Mine are a tad stiff, and I replaced the seals in mine last fall. I can turn them one-handed while riding though, if that gives any indication of stiffness.

Bikebandit has the seals in stock for $11.46 each though. Part number 8471-01. The fuel should just DUMP out of the hose when opened. Prime bypasses the vacuum, so there is obviously something stopping the flow. Have you removed the filter screens on the towers, and cleaned them out? Try assembling it so that it is in the Prime position without having to turn the knob, then test. That way you know the seal is in there the way it's supposed to be.

[dbeardslee]

Did you have both petcocks apart at the same time? There are left and right parts, so if any got switched from one side to the other it might account for what you describe. Also, if you didn't get the rubber gasket with the multiple holes back in the right orientation that might do it. I went around and around with rebuild kits and leaks, and finally just s-canned the vacuum petcocks and installed aftermarket petcocks from Partsnmore. Haven't had a problem with petcocks since then.

[bgrubb7]

Nope, one at a time. I took the second one apart, while I reassembled the first so I made sure to get it back together properly. I'll check it for the third time, and try reassembling in the prime position.

Everything was cleaned, including the filter screens. When the seals are out, there is no obstruction, so it has to be a matter of seals not in right, or the diaphragm not opening all the way.

I've already decided not to mess with the rebuild kits. I'll go the aftermarket route if I can't get these to work. Z-1 has some manual petcocks for 12.99, but their adapter plates are $25 a piece

While Parts n More has $6 adapter plates, but their petcocks are $29. Anyone know where I can get cheap petcocks and plates at the same place?

Also, there was a link around here where someone filled the back of the knob with solder, and bypassing the vacuum function essentially making it an on-off valve? I'm not finding it, or maybe I'm stumbling right over it.

[bgrubb7]

Also, there was a link around here where someone filled the back of the knob with solder, and bypassing the vacuum function essentially making it an on-off valve? I'm not finding it, or maybe I'm stumbling right over it.

Never mind I found it.

http://www.xs11.com/forum/showthread...petcock+solder

[jjwaller]

Can't find the thread.
Do either of the Mikes-XS manual petcocks
fit the E standard tank?
http://www.mikesxs.net/products-34.html#products
There are 3, One set is left and right, and a third one.
He doesn't list dimensions.

[bikerphil]

Yep, I did that solder mod. After the solder was filed down, I tapped it out and JB welded it back in place. I've been running it that way for some time with no problems. Prime position is now off position.

[Incubus]

The Mikesxs petcocks fit a standard tank. I have them on Succubus, my '79 Standard. The original petcocks I keep hanging on the shop wall to teach me humility.

Patrick

[bgrubb7]

Yep, I did that solder mod. After the solder was filed down, I tapped it out and JB welded it back in place. I've been running it that way for some time with no problems. Prime position is now off position.

Did you take the diaphragm out or leave it in?

[bikerphil]

Did you take the diaphragm out or leave it in?

I left the diaphragm in to serve as a gasket, but moved the spring to the other side to force the diaphragm in the open position, instead of the closed. I also plugged off the vacuum port on the petcock.

[jjwaller]

The Mikesxs petcocks fit a standard tank. I have them on Succubus, my '79 Standard. The original petcocks I keep hanging on the shop wall to teach me humility.

Patrick

Yes, but is that the left right pair, or the stand alone one
(of course you need 2)?

[bgrubb7]

I left the diaphragm in to serve as a gasket, but moved the spring to the other side to force the diaphragm in the open position, instead of the closed. I also plugged off the vacuum port on the petcock.

I really like this idea ans might just do it in the future. For now, I did end up getting mine to work. There was still alot of crud inside the filter screens that kept settling down into the fuel passages. I didn't take the screens off the first time because I was afraid I'd break them. I managed to get them off this time, and instantly saw the problem. They did leak a bit at first, but I bent the washer in the front a bit to put a little more pressure on the main seal, and bent the diaphragm spring out a bit to put a little more pressure on theo-ring, and now everything works. There is still a very slow drip, but I have good float valves, so the carbs aren't overflowing.