Saving a '81 KZ750-E

Nessism wrote: I've experienced a similar snafu with a tank before. To bring the edges in I traced out the hem flange pattern on some wood, used a flat blade screwdriver to pound the board and create the groove, nested the tank on the boards, then used a mini sledge to pound the board on one side, while supporting the other side against a wall, until the tank was back in shape.

That is a clever idea! I do have some 2 x 6's left over that are close to the tank length. Anyone have a similar tank that can get a width measurement off of, seam edge to seam edge? That would give me a target number to work with.

Using the wood to apply pressure to the seams worked out. Turns out the tank was splayed out well over an inch. I had already reduced it by beating the inside bulge down, so not sure how far it was out.before i used the trick with the wood, it was 1.060" over the target. I now have it within .030". It still doesn't sit flat on a table but that will have to do.


The buckle in the stiffening rib is almost gone. This is a before and after comparison.


It fit on the bike fine now. I'm going to chalk up this hurdle as overcome(and a huge learning experience!).

Nice work! It would have sucked if you couldn't fix it after all that work. Looks perfect on the bike now.

Great work Skidmark, learning by doing. We all sometimes only learned the hard way but we learnd our lesson.

First pass on the exterior bead blast. Just a couple small areas to hit again.

I am trying to eliminate flash rust when cleaning and rinsing out the tank. My goal is to end up with a dry, rust free interior. Using the POR15 Cleaner/Degreaser, the instructions call for a water rinse, then dry with a heat gun. This causes flash rust. They recommend coating the interior with their Tank Sealer product, which they say is formulated to bond over light flash rust, so having it is okay. I do not want to run any sealer. Is isopropol alcohol the thing to rinse with, or is there another method to eliminate the moisture in the tank without having flash rust occur? I used WD40, but that will seep out the openings and mess with the paint process. I am doing another cleaning to get all the WD40 out of the tank, and hopefully the last of the black tar/old fuel spots.

A new pin hole leak, right where the buckle in the rib was. That's two leaks now that require weld repair.

Yesterday I found some small areas left of the old fuel - blackish, tar looking deposits. I did another wash today using the POR15 Cleaner/Degreaser but instead of mixing at 4:1 with water, I mixed it at 2:1. I drained, rinsed, and dried the tank. The bore scope shows the last deposits of that stuff are finally gone. I now have a stripped, dry tank ready for weld repair. After the welding is completed I will need to go after the rust with another phosphoric acid wash. This is where I want to end up rust free, and not use a sealer. I'm just not sure how to water rinse and dry the tank without getting the flash rust.

Do not weld the pin hole, it could be enlarge. Use a gas torch or big soldering iron, some flux and tin to seal the hole.

Should I use the same technique around the perimeter of the rear mount bracket as well? I was panning on having it TIG welded 100% around. the other leak is inbetween the tank wall and that spot welded bracket.

The Problem on the rear mount bracket is to clean the surface to bare metal if you go the solder way. If any rust, paint or grease is left over it won´t let the tin penetrade the the metal parts fully. I would give it a try, because tin is easy to remove as an Tig welded hole in the tank.

I've never messed with it but there is body solder sold in large sticks. In the past when doing tank work and plugging leaks I used silver solder. Unfortunately, the metal in the tank is weak at this point after all the rust. A prime candidate for a liner...