Save the Tank No Save The Tank

The fuel tank off the parts 1982 GPz750 I just scrapped is largely straight and dent free. The inside is rusty.

I'm considering getting the tank professionally treated at a local gas tank renu place where they guarantee their treatment and coating not to leak or release for 10 years.

I can't find a decent tank that has sold on eBay in the USA to gauge value.

If I treat the tank and then have it repainted OE color with the stripes I will have a complete set of 1982 GPz750 body. Fairing, tank, fender, covers, tail. All nice. What would be the value of this package? Thoughts welcome.

I just now remembered the bike also came with a race (center collector) Kerker head pipe. I need to get that bead blasted and painted soon.

Gas tank renu web site

I asked a question of this group regarding my tank.  It had a little rust in it, but not much.  I was essentially told that unless it leaks, don't use a sealer in it.  I was advised to just clean the rust out, which I did, and then use the tank.  I'm glad Iistened the advice.   I saved time and money.  If the inside of your tank isn't that bad, you might want to clean it out yourself.

Agree.  Derust yourself.  Be sure to remove the petcock, sending unit, and any other sensors inside the tank.  Fabricate plugs to prevent leakage, but allow the tank to vent while derusting, or at least, release any pressure that may build up.

This seems like good stuff. More mild than many other derusting methods, and cheap.

1 liter of water
100 grams of citric acid (available on Amazon)
One of the following: 40 grams sodium carbonate (washing soda), or 63 grams sodium bicarbonate (baking soda), or 30 grams sodium hydroxide (lye)

Scale volume of solution as needed.

This stuff derusts better than Evaporust, while being safe and mild with the base material. It lasts much longer than Evaporust also.

Never use harsh chemicals like hydrochloric/muriatic acid to derust. Yes, that stuff is fast, but it's crazy harsh and should be avoided.

What's a complete set of 1982 GPz750 red cosmetics worth, with a the mean-ass Kerker that makes oil changes a serious pain in the ass? $1500? $900? $2000? $800?

If all those mentioned are sold as a set, including the Kerker, and they are in decent shape (not needing a repaint, etc.) you might ask in the neighborhood of $1200 to $1500 or so. You might consider selling the Kerker separately, in which case the bodywork might bring $1000 to $1200. The fairing will sell much quicker if you include the mounting hardware and the gasket between the windscreen and the fairing body. The tank is fairly unique, right sidecovers are common but left sidecovers are getting rare and pricey. Front fenders are also somewhat unique and are different than the 1981/82 GPz1100 front fender (although many say, incorrectly, they are the same. The tail piece is very common and shared with many models. Then again, there has to be someone out there who wants all these. Hope this helps.

To find out if a tank has soft spots that will turn into pinholes which will ruin your new paint job is a very long job. 
I soaked my tank with 7% cleaning vinegar  (evaporust did not exist at that point and time) until all rust was gone. 
I then made a plug for every orifice in the tank and glass beaded it at work. Glass beads are very mild and won’t blow through thin metal unless it was already past paper thin. 
If you find pinholes, you can solder or braise them shut and then you will have to get the tank lined.
If the tank seems perfectly fine after glass beading it, then do a basic primer coat, fill the tank with fuel and let it sit for a week. If no wet spots appear in the primer, then you are probably safe to paint the tank. 
My zr550 tank developed pinholes after chemically stripping the inside.  I soldered the holes shut, lined it with Red-kote and had it painted. It’s been fine for 10~years so far. 
Your results may vary…..
 

What makes the tank unique? It looks exactly the same as the tanks I have here for the KZ750L3 and the KZ700. There is no difference other than color?

chopper1963 wrote:

What makes the tank unique? It looks exactly the same as the tanks I have here for the KZ750L3 and the KZ700. There is no difference other than color?

Yep, those are the only two models that the 1982 GPz tank compares to. Those two models are also increasingly rare.