Saving a '81 KZ750-E

There are tons of new petcocks on ebay that fit your bike for less than $30 shipped.  44mm spacing.  Worth a try, compared to drilling the tank.

I drained my tank and removed the stock petcock.  The bolt spacing is indeed 44 mm as Nessism stated.  I called Pingel, and Steve says they have the adapter plate to bolt to the tank and allow their petcock to thread into the adapter.  I would like to ditch the vacuum feed feature.  Is the KZ650 a vacuum feed as well?  I remember earlier in my build I was a bit reluctant to spend the money for a Pingel as they are not cheap.  Well, they are even higher now.  Around $175 for the valve, and another $45 for the adapter plate.  I know their stuff is very good quality.  Sometimes it's worth the money to get top grade parts.

I would never drill the tank!  After what I went through to get this tank rust free, and then leak free, it will remain as is.

Yes I had to use a die grinder to open up the slot, where the petcock  goes. I just opened it it up enough for the Pingel tube to fit in. Also I did this before I cleaned the tank. I know this doesn't help you Skidmark, as you are so far along with this bike, and I would also not want to be making mods at this point. for me I wanted to lose the vacuum line. I never liked that system anyways.
I also had done some searching for alternatives to the Pingel, but it was smack dab in the middle of COVID, when it was full on stupid trying to get anything, and the Pingrl made the most sense to me.
I mainly wanted to bring up the possibility of the vacuum line leaking into the #2 carb, hopefully to stop another tear down if it wasn't necessary.

You will need to file, grind or drill the hole larger in the bottom of the tank to let the Pingle petcock fit.

The Suzuki vacuum petcock with 44mm spacing is a dirrect fit, and I've been using it for many years with no issues.

Petcock - Vacuum - 44mm - Suzuki | Kawasaki and Suzuki Motorcycle Parts | Z1 Enterprises

I want to eliminate the vacuum on the petcock.  My new Pingel petcock showed up today.  Now on to the carb sync.

Before I start to open the petcock opening to fit the Pingel unit, I am drying and airing out the fuel tank.  I rechecked to float levels (again), and I started to ponder...  I used new intake boots on the cylinder head.  I did not use any kind of sealant since they have an o-ring.  Should I use a light coat of Kawi-bond on the head surface before they are installed? I am also thinking I should use loctite on the manifold screws as well.  As long as the intake system is off the motor it would be a good time.  What's the consensus?  I want to make sure all bases are covered to get this intake system tuned in.

wrote:

Before I start to open the petcock opening to fit the Pingel unit, I am drying and airing out the fuel tank.  I rechecked to float levels (again), and I started to ponder...  I used new intake boots on the cylinder head.  I did not use any kind of sealant since they have an o-ring.  Should I use a light coat of Kawi-bond on the head surface before they are installed? I am also thinking I should use loctite on the manifold screws as well.  As long as the intake system is off the motor it would be a good time.  What's the consensus?  I want to make sure all bases are covered to get this intake system tuned in.

I wouldn't loctite the screws, the "O" rings hold tension on them and I have never hear of them coming loose (seen lot's broken off in the head though)

Negative on sealer or loctite.  Not needed.

 

I followed all the instructions from Pingel, and I am happy to report that it is sealed up on the first install.  However, I now have a fuel leak at the low fuel indicator sender.  Time to remove it and use a cover plate.  It appears I am also leaking fuel at the "T" between carb 3 & 4 were the fuel line attaches.  These were all leak free before.  I don't know if the o-rings need to swell to seal, or if they shrank from having the tank dry.  I just drained the tank again so I can remove the low fuel sender.  While draining the tank I noticed the flow would slow down until I rocked the tank, then the it would go to full flow again.  It appears my tank is not venting.  I put a replacement fill cap on the tank from Z1 Enterprises that looks exactly like the stock one.  Anyone had to create a vent hole in one of these to keep a Pingel flowing?

The fuel Tee and transfer tubes use 2.0 x 5.0mm O-rings.  Buna N O-rings will swell with gas contact, but yours shouldn't have shrunk enough to leak after only a short time like this.  

After removing the fuel cap and disassembling it, I determined this to be a good spot for a vent hole.  After re-installation the Pingel petcock flows at full force.  So beware some of these repops may not be everything the OEM one was.  My original fuel cap was so far corroded I threw it away once I got the new one.  Should have waited, I guess.  It works now.  Time to get the tank back on and see if the carb "T" is still seeping.

I took the fuel "T" out from between #2 and #3 carbs to put new o-rings on.  O-rings were not the problem.  I have a cracked fuel "T".  This part is no longer available.  Anyone have a spare they would be willing to sell?