TOPIC:

Anyone know of a aftermarket petcock that will fit my 81 kz1000j without modification of the hole in the tank? The vacuum petcock on my bike doesn't stop the fuel from leaking into the carbs. The last thing I want to happen is for the engine to fill up with gas. I bought this bike from the original owner and I noticed in his paperwork that he had bought a replacement factory petcock years ago. These petcocks must not be very good even though they cost $100.

Those petcocks are great, it's the gas that's changed. I've had the one on my 1977 KZ650 since new. I've had to replace the rubber pieces in 1992 and haven't touched it since. The rubber diaphragm gets eaten up by the alcohol in modern gas. Get a rebuild kit for it and fix it.

The funny thing is, I bought a k&l repair kit for this petcock. I didn't work. It won't shut the fuel off. Also, the round gasket with the 4 holes in it just behind the petcock lever swelled up and became so tight, I had to loosen the screws just to turn the lever.

Repairing or replacing a vacuum petcock would be normal maintenance >> not unusual & not necessarily an indication of the quality.
I would contact K&L about the failed kit, but in the meantime check to see if the oem parts are still available. If so, a new Kawasaki diaphragm assy & tap gasket are usually pretty cheap. probably less than $30 for both.

Manual fuel valve. If you want to switch to a manual unit, measure the bolt-hole space center-to-center, then check EB to see if anything is available. OEM Yamaha Raptor Grizzly fuel valves are reasonably priced & made in Japan. I think they're 34mm c-to-c. I wouldn't get a cheapo aftermarket fuel valve >> crummy chinese china junk.

K&L petcock parts are very hit or miss. If you can get OEM parts you are MUCH better off.

Pingel petcocks are a top shelf aftermarket fuel valve.
I have one on my bike with no problems since 1980
Dave

The vacuum petcock will need to be cleaned and have the soft parts replaced every couple of years, especially if you have to run E10. It is very important to insure that the internal sealing surfaces are in great shape. I use aluminum polish on the face of the lever and on the seat where the small oring actually seals fuel flow, every time I replace the rubber bits. If the seat is pitted, the petcock will likely leak no matter what else you do.
As martin_csr noted, what we have today is a far cry from the fuels we had when these bikes were new. There are many new additives, including the ever-popular ethanol.
If you convert to a manual valve, Dave is right, Pingle is as nice as they come, but they are not cheap.

I had/have the same problem with mine. I went through 2 rebuild kits (cant remember the brand). There is a very good tutorial on restoring these taps. I think its from an XS 650 site. I dont have a link but its a pretty well known tutorial , maybe someone else can point you in the right direction. It didnt solve the problem for me though and I ended up fitting an on/off tap in line twixt tap and carb. That worked.

Fuel has been getting worse for some years now, I have been using regular unleaded in all my bikes , with a dollop of some sort of additive every now and again. Here in Holland the regular unleaded has recently been replaced with E10 which Ive been warned off from, so, Ive now switched to super unleaded. No noticable difference in my daily ride but I havent tried it in the Z yet.

Higher octane fuel will work fine in a Z. I use Shell 91 or Chevron 94 whenever possible. I avoid fuel with ethanol except in my KLR650, which is a 2008 model designed to use up to 10%.

Here all normal fuel has ethanol, so there's no avoiding it. However, it has not caused any problems with my original 1977 KZ650 petcock. This is a manual petcock, not one that is operated automatically when the engine is started, so it has no diaphragm to go bad. I have always used 93 octane as this was recommended by the Kawasaki dealer that sold me the bike when it was new in 1977. Ed

I have had the same problem, regardless of using OEM parts the petcock didn't close when the vacuum let go. Not until I took it all apart and vapor blasted all parts, including removing the brass nipple on the lid, removing the small "kex" that acts as a check valve on the vacuum hose and blasting its seat, I got it back to perfect working order.
It is easy as pie, but it needs to be perfectly cleaned to work alright.
Brgds Anders