Petcock Leaking after Rebuild

I recently rebuilt my petcock with parts from chacal, and it is leaking pretty bad. I changed the wave washer, washer that goes around the selector, selector valve washer, and the diaphragm. The petcock is leaking from that vent in the plastic spacer. That spacer did not get changed, but a new spring and shim have been added. So is that spacer just bad? All my surfaces are very clean. What should I look to next? Fuel is literally spitting out of that vent.

 

Mine didn't seat on the diaphragm side the first time I installed it. Very important that the diaphragm be in the proper position with no wrinkles or folds. Nothing to do but remove the diaphragm cover and carefully reinstall. Maybe a light coat of silicon grease would help keep it in place.

 

What do you mean when you say it didnt seat? Are you talking about the little head that goes in the orifice with the oring on it? I have taken it apart and back together numerous times. I have made sure the diaphragm was very flat before tightening. It doesnt seem to be leaking from the fuel outlet when there is no vacuum, as it should. But when I install it and run vacuum through it gas spits out of the vent. I dont mean just a few drops, it literally squirts out of that vent.

 

Yes, I did mean the plunger with the small o-ring. I'm beginning to think these things are cursed, 'cause mine started leaking again. I've pulled it and reworked it according to bigfitz52's instructions,,but I'm still having problems. When you say coming out of the "vent" are you talking about the small vent on the plate that holds the diaphragm or the fuel outlet? If it is coming out of the small vent then the diaphragm is bad. Take a look at this link--- http://www.xjbikes.com/Forums/viewtopic/t=25058.html

 

My petcock started leaking and needed to be rebuilt but I just got a new one from Chacal instead of messing with it.
He sells one that has the fuel outlet at a 45 degree outward angle that gives room for a nice in line filter.

Maz

 

If there is fuel leaking from the plastic spacer that means there is a leak in the diaphram or it is not installed correctly. There is a indexing pin in the spacer with a matching hole in the diaphram, they must be lined up. Over tightening the screws can cut the diaphram making it leak. Either way the chances are good you need another one.

 

There is not a problem with the diaphragm and it is installed correctly. It is new from chacal. But the diaphragm does not seal fuel off from that vent. The vent is positioned on the inside of where the diaphragm would be, which means fuel would flow past the plastic piece before the diaphragm. If you look at that plastic piece it has a sort of molded in gasket. This gasket is what is supposed to keep fuel from leaking past and to that vent. I think my plastic spacer is not creating a good seal, whether that be because that molded gasket is too worn, or the petcock mating surface is deformed.

But the diaphragm does not seal fuel off from that air vent.

 

same problem with my xj700n. So tonight I removed the petcock again, bought a polishing wheel for my Dremel and some wet sand paper and really cleaned and polished the seat and all flat surfaces. Even removed and cleaned the check valve disk in the vacuum nipple. Put it all back together, using a very light coat of silicone grease on all flat surfaces, and it works perfectly. Moral of the story, follow bigfitz52's instructions to the letter if you want it to work the first time.

 

I did follow the instructions. My surfaces were shiny and clean.

So I took it back apart yesterday, and I had a few problems with the rebuild kit. When I took the rubber parts back out (selector valve washer, seal around selector lever, and tank o-ring) they had all sort of expanded in size. So now they are all too big.

I do not want to spend anymore money on this old petcock. So I just converted it to a on off valve. I did this by removing the plastic spacer, and installing the diaphragm with the spring, shim, and cover on top of that. This insures the plunger creates a good seal, and gas can no longer come through that orifice. So the only way gas will flow is if it is in PRI.

So pretty much now PRI is on and the other 2 are off. I will just buy a new vacuum petcock when everything else is running the way I want.

 

Interesting solution. Just have to watch and make sure you don't run out of gas now that there is no reserve function. Like my first Cushman, look in the tank and if there's gas, then you're good to go. By the way, I had the same problem with some of the o-rings swelling, but fortunately I retained the original ones that were still in good shape and was able to re-use one of those. Have no idea what caused the swelling.

 

There is a seller on ebay selling brand new non vacuum On OFF RES aftermarket petc0cks. They are the same cost as the rebuild kit and after reading about all this hassle I'm going to try one.

 

Are you sure that they are direct fit petcocks or due you have to manufacture some kind of spacer to accomodate the new petcock?

Either way put the ebay details up, so we can all see it please

 

Alcohol (ethanol) in fuel will cause rubber to swell............fuel lines and float valve needle tips, too.

 

I browsed through this thread and didn't see if you said explicitly that you used silicone grease during reassembly. Petroleum-based greases can and will cause the swelling you described. But since chacal responded without mentioning that, I'll presume you bought some from him -- and he's assuming you used it.

 

On the subject....
Mine has developed an issue gas in the vacuum hose
Am I looking at a damaged diaphram?

 

Here is the link.
http://www.ebay.com/itm/NEW-AFTERMARKET ... 0d&vxp=mtr

All good feedback minus the couple people who bought the wrong one.
No one says it didn't work. You would need to search for your model though, as it looks like that one is 750 only.

 

Thanks my friend, I've contacted him

 

I did not use any grease during assembly. i also had to reuse my old parts. It does kind of suck not having any reserve function. But like I said this is just temporary so I can focus on other areas of the bike that need more attention right now. Like this damn lean condition I think I have.

But that manual valve will definitly be in the future for me. While the vacuum idea is nice, I am not going to spend another 50 bucks for this thing to still not work.