King size gas tank problem

This thread needs more pictures

The original construction method on the Z1 tank appears to be the bung is gas welded to the tank shell from the inside before the the bottom and top shell are welded together. That is how the filler cap opening was also done. The spot welded base plate is there just for reinforcement or possibly to make it easier to gas weld the thicker bung to the thinner tank sheetmetal. I think the base plate was spot welded to the tank shell before the bung was welded in. :blink:

Hey Dave, by all means start a thread with loads of pics. Good luck with your bung problem and I don't think you're going that way but JB Weld is gasproof.Don't ask how I came to know this...I'd also be interested in your painter's thoughts on RD stripe kit application and clearing to finish.

Thanks for the info Paintworkz. I am going to try one of those flex cameras down the cap to look at the inside of the bung this week to get a better idea of the internal weld method. The threads on the bung seem to thread onto the base plate as there is a good groove visible around where the bung enters it. I would agree that this adds rigidity to the tank bottom and as this tank has the inner seams it would have allowed manufacturing to access the area for brazing before completing the assembly.
Hi Jack The painter I used is the recommended painter for RD who is in Brantford. My LTD was done by him and he has been clear coating this stuff for a while; in fact, he says he will guarantee the job as long as you own it! I have had no issues with my LTD to date and there is enough clear to buff out any accidents. I'll pm you with the details.

check out these adapter plates.

www.pingelonline.com/powerflo.htm

JB Weld is no good with gas. been there.

Bummer 'bout yer bung man!
Fwiw, I'm a firm believer in JB-Weld. My step daughter backed over something in her old '74 Nova years ago and punched a small holle in her tank. I emptied it, drilled a screw hole through it, sanded the area clean, then slathered JD Weld on a sheet metal screw and a fender washer and screwed it in. She drove that car another six years before she sold it. That was from 1985-91. And the guy that bought it in '91 is still driving it today.
I have no doubts that if you glued your petcock on with it, it will last at least until it's time for your next petcock rebuild.

Kawboy,

Let us know what you see inside with the camera. I thought the factory gas welded the bung in from the inside, but brazed them on the outside only if they leaked.

If i was in this situation i'd drill the bung to where there are is no more threads left which is about 22mm,then find a pipe that will fit the petcock then tap the base with new threads then seal it with teflon paste when installing it

Finally a positive outcome to the dilemma! Used the camera down inside the filler cap and saw the top of the bung inside the tank. Looked as though a piece of 1/4" rope was laid around the top of the pipe as it sits about 3/16" above the bottom of the tank. We tried a pipe internal easy-out to try and break it free which scared the crap out of me so that idea was scrapped; didn't want to distort the tank wall. Finally resorted to hand hack-sawing a piece of the pipe out which took some time and allowed some large pliers to grip and pinch the pipe. Most of the pipe came out leaving some behind which had to be nibbled away with needle-nosed vise grips and the balance being punched down into the tank. Some small amount of sealant was left behind which I should be able to get out with a tap but am trying to determine if it is a pipe thread which tapers. Will have a friend make up a new bung to thread in with some hardening sealant which should do the trick. I am really trying to fire this bike up on Labour Day weekend as I don't want the rings sitting any longer!
I hope this lets others see what happened here to deal with these types of problems before paint. I was lucky, no paint scratches to speak of.Will still follow with some pics.
David

By the way, the stuff that looked like rope seemed to be really poor looking metal as it was very grey looking and somewhat porous but hard as all get out!
David

I think the stuff that looked like rope and the seemed to be gray pot metal was a gas weld bead......maybe.

Finally some pics of the finished tank having solved the bung dilemma! Could not salvage the inner thread so a tap was used ( 7/8"x18 ) I believe. Had an adapter made by a very astute machinist with corresponding thread, some shoulder for installing with a socket and the outer 22mmx1.0 thread to install the petcock nut. Coated the inner thread with JBWELD after cleaning with alcohol and added JBWELD to adapter then threaded it into the tank making sure there was squeeze out which was carefully tooled. Made sure the area around the opening had the paint carefully ground off to assist with adhesion which was quite disturbing to watch I might add but turned out awesome. Applied some flat black paint tonight to make it disappear, applied tank badges and finally was able to install my restored gas cap/gauge. I hope after all this my petcock doesn't leak!
Installed my tach last weekend after trying some airbrushing with nephew who has way more patience than me when it comes to masking. Had a bunch of new glass cut for this purpose and while the white lettering differs from both slightly, I like the newish look.
On to the carbs, hope to run it soon!
David