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Success spreading a YZ80 gas tank

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For those of you who haven't been keeping up, we've opened a discussion on what gas tanks will fit the XT/TT frames. Today, I took a YZ80 tank and removed the petcock, stuck a rubber tipped blower in the hole, screwed the cap on and widened the tunnel to 5" at the edges with 100 lbs. of air pressure.  It expanded so easily! Dents should hv popped out if I'd put a strap around it to keep it from bending hopelessly out of shape.

This was after a week of filling the tank repeatedly with apple cider vinegar, letting it sit for a couple of days, straining the rust flakes out of the vinegar through a tee shirt stretched over an oil pan, then putting the vinegar back in for a couple more days, then repeat a couple more times. Lastly, I put some square nuts in there and danced all night to knock off whatever rust remained. Now the tank looks shiny new inside and is ready for the Kreem tank relining kit.  It's just great when something works and you don't screw it up trying, isn't it?   Post script:  The Kreem treatment was successful.  Now I have a smaller gas tank that fits the fat backbone of an XT500.  

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I did much the same with a badly dented TS tank. Both sides and the top had been bashed in.

Rather than use a large volume of compressed air. I filled the tank with water right to the top after sealing the outlet and making a rubber bung for the fill point with a shrader valve from a tubless car rim in it. Then connected my pushbike pump and carefully built of the pressure in a controlled manner. I had a small ratchet strap wrapped round the tank to stop it splaying.

The main volume of the dents came out easily, and I then gave the edges of the residual dents a light dress with a flat bar in old skool panel beating style to bring them back to the proper shape and take the tension out of where the metal had been bent inward.

With only a small volume of air used to compress the tank it makes it safer in the event of any blow out / leak.

If I was younger I would have filled the tank with gravel, put it in a rucksack, then headed out to a rave and danced all night to get the rust out! If only DeLorean had made fuel tanks...

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1 hour ago, rmxdan said:

I did much the same with a badly dented TS tank. Both sides and the top had been bashed in.

Rather than use a large volume of compressed air. I filled the tank with water right to the top after sealing the outlet and making a rubber bung for the fill point with a shrader valve from a tubless car rim in it. Then connected my pushbike pump and carefully built of the pressure in a controlled manner. I had a small ratchet strap wrapped round the tank to stop it splaying.

The main volume of the dents came out easily, and I then gave the edges of the residual dents a light dress with a flat bar in old skool panel beating style to bring them back to the proper shape and take the tension out of where the metal had been bent inward.

With only a small volume of air used to compress the tank it makes it safer in the event of any blow out / leak.

If I was younger I would have filled the tank with gravel, put it in a rucksack, then headed out to a rave and danced all night to get the rust out! If only DeLorean had made fuel tanks...

My original intent was to pop out a dent in the tank but it opened up so easily that I forgot all about that til later.  Now I'll add the strap and use your method on the dent.  A tubeless tire valve stem is a great idea.   I'll use a cut off valve in my air line to avoid problems.  

Edited by Jimmy Pascol
Clarification.
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I just did a stock tank on the week end. didn't have much luck getting the dents out . I destroyed an aluminum 78 XT tank with air a few years back. It splayed open immediately.  I like the water and air idea. I may also consider drilling small holes in the underside of the tunnel to get some wood or metal dowels in behind the dents to push them out on the next tank. I started on this last Saturday stripped it polished it tried with little luck to pull some dents. then gave up and painted over them ... It's a race bike it'll need fixed again later .      

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Decals by Diablo Cycle. Same kit as a 79 XT500 but in the colors I requested.  Black/Yellow instead of White/Red 

 

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Edited by BruceD_500

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Contact some new and used car lots for a referral to a paintless dent removal outfit.  They go around to car lots and repair door dings, etc. without cutting or welding.  They have tools to massage the dents out from the inside.  

Edited by Jimmy Pascol
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For anybody who hasn't been keeping up, it's time to do a final fitting of the YZ80 tank on my XT500.  First, the underside needs some violent modification to eliminate some humps.  I'll use Brent J's wooden tool but really shoulda done it earlier.  Also, the rear of the tank is still too narrow for the frame; but I made a spreader out of 3/4" square tubing with a LH tread nut welded in one end and a RH threaded nut welded into the other.  A few turns on the square tubing should do the trick to get that final 3/4" width needed to clear the triangulated frame reinforcement at the backbone under the rear of the tank. Let's hope I don't crack a weld but I've learned a lot so far.  Next, will somebody get started on a CR125 tank and let us know how much modification it takes to make it fit an XT500?  It's small and hs bn said to come close to fitting.  

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Edited by Jimmy Pascol
Enhancement of narrative.

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