82 kz650 CSR petcock on a 78 kz650 B2

I have an 82 kz650 CSR petcock laying around, and am needing to rebuild my 78 kz650 B2 petcock.

I've done some pricing and found a kit for the 82 petcock for $13, and the kit for my 78 petcock is eluding me. I've seen one in the past for the 78 for over $35.

So now I have the bright idea of rebuilding the 82 petcock and installing it onto my 78 kz650 B2. Will this petcock work ??

Measure the bolt hole spacing. The 78 should be 44mm & the 82 is probably 34mm (the 81 is 34). Assuming the 78 is the vacuum type, I don't know if the rubber parts are interchangeable, but you could compare part numbers at Partzilla.

Beware of cheap kits. Get made in Japan --- an oem or K&L diaphragm should be in the $20 range. A complete K&L rebuild kit will be approx. $35 or so. This is one of those cases in which oem is preferable & maybe even cheaper.

Sorry for not responding before now, been sick. Anyways, I checked the mounting bolt hole spacing, and there the same on the 78 and 82. So will the 82 petcock function properly with the 78 carbs ??

Yea martin_csr, you've been correct before, and you might be again, with your warnings about the cheaper parts made for our bikes. I've already purchased the kit for the 82 petcock, so if that petcock will function properly on my 78, I just as well give it a shot......OR.....

What I would really like to do, is gut the 78's petcock, and then run a simple on / off fuel valve after the petcock. Do you know if this will work with the 78's carbs ??

The vacuum petcocks function basically the same --- they don't care what year or model the 650 is.

Using an in-line fuel shut-off valve shouldn't be a problem.
Instead of gutting the stock petcock, I would install a manual fuel valve in its place.

Are there Kawasaki manual fuel valves that will bolt to the 78's tank ?? I'm guessing I would have to find one from a different year / model Kawasaki ?? Any suggestions what year / model bike to look at ??

Yes. The petcock used on 1977 KZ650 models (part number 51023-057) is manual and will fit the 1978 KZ650 fuel tank. It has "RES"; "OFF"; and "ON" positions. Here's what it looks like. Ed

Great !! Thanks 650ed !!

I have one more question. Do I just block off / cap the vent nipple on the carbs ??

Not the vent nipples. Put a rubber cap on the vacuum nipple on the #2 carb. Ed

There might be an aftermarket manual fuel valve that will fit or one from a different Japanese make. I know Yamaha has one with the 34mm bolt hole spacing & there are aftermarket fuel valves identical to it --- the Yamaha part is pretty cheap, around $25 or so.

Another option is to get an adapter plate & Pingel fuel valve. The Pingel has a round screen, so to fit the oblong opening, you have to ream the hole approx. 2-4 mm.

Great info guys !! I'll do some checking around, and let you know what I come up with.

Is there a source available, that gives the mounting bolt hole spacing on the different petcocks ??

Not that I've ever seen --- something like that would be handy, wouldn't it.