Tanked
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- tz375
- Moto GP
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- Joined: Mon Nov 03, 2008 10:47 am
- Location: Illinois
Tanked
Anyone here had any experience repairing tanks with rust holes?
I picked up a tank recently, thanks John (Bighole), and the paint was blistered from rust. When I scraped off teh paint I saw some rather nasty low spots in the metal where the rust was eating its way through.
I fact in a couple of small spots, the tank is rusted through. Most of it is sound, but where the seat rubbed against the back of the tank is the worst area with several small holes.
I have filled the holes with braze and an oxy torch, but I this is not exactly my area of expertise and I'd hate for a fuel tank to leak fuel all over a hot motor when I'm riding it. That would be decidedly sub-optimal.
So does anyone have any advise as to the best way to repair a gas tank?
I picked up a tank recently, thanks John (Bighole), and the paint was blistered from rust. When I scraped off teh paint I saw some rather nasty low spots in the metal where the rust was eating its way through.
I fact in a couple of small spots, the tank is rusted through. Most of it is sound, but where the seat rubbed against the back of the tank is the worst area with several small holes.
I have filled the holes with braze and an oxy torch, but I this is not exactly my area of expertise and I'd hate for a fuel tank to leak fuel all over a hot motor when I'm riding it. That would be decidedly sub-optimal.
So does anyone have any advise as to the best way to repair a gas tank?
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- To the on ramp
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- Location: Hudson Valley, NY
I'm no expert. Although I'm in the process of refurbishing a couple of tanks right now.
Any way you could post a couple of pics for the experts to weigh in on? I know there are some tried methods such as tank lining. But I'm gathering that yours may need a bit more help in spots.
Any way you could post a couple of pics for the experts to weigh in on? I know there are some tried methods such as tank lining. But I'm gathering that yours may need a bit more help in spots.
So many Projects - So little time
- Coyote
- Moto GP
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The POR15 gas tank repair 'kit' comes with a section of cloth for repairing open holes. I haven't had to use it, but it is applied with the tank liner.
If it were me, I would have the tank glass bead blasted so you can see what you are really faced with before throwing money at it. Bead lasting might reveal that it's too far gone to fart with. Good luck!
If it were me, I would have the tank glass bead blasted so you can see what you are really faced with before throwing money at it. Bead lasting might reveal that it's too far gone to fart with. Good luck!
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- Yeah Man, the Interstate
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Coyote wrote: If it were me, I would have the tank glass bead blasted so you can see what you are really faced with before throwing money at it. Bead lasting might reveal that it's too far gone to fart with. Good luck!
+1
Rust likes to hide and 'never sleeps!'
Bead blasting is the only way to be sure. Ask Fang, he had a nice paintjob only to go to crap due to hidden weak rusty spots.
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- AMA Superbike
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Yep, I agree. Find out what you really have with either bead-blasting or careful use od Muriatic acid. A good welder/body man could easily replace missing metal, and then a tank liner (POR-15 of course!) would "seal the deal".
Lane
Lane
If you stroke it more than twice; you're playing with it.
Too many bikes, too much time, ENOUGH SPACE, FINALLY! Never enough money.........
Too many bikes, too much time, ENOUGH SPACE, FINALLY! Never enough money.........
- tz375
- Moto GP
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- Location: Illinois
Thanks for the input guys. i hadn't thought about using muriatic acid. I have a large bottle of that here somewhere.
So far i have stripped off most of the paint and wire brushed the rust spots. At the rear where the front of the seat rests against the tank there are through holes and on the side, it hasn't broken through but the holes are quite deep in places.
Then I panel beat out most of the dents - some were easy are some were next to impossible, but we're getting there.
Next I tried bronze welding with a small tip and low pressure on the oxy torch and it looks like it might work. There's some shrinkage, so i have to be careful I don't end up with a tank full of lumps and dents.
But there's still too much rust on the inside for my liking, so I'll try to get it blasted tomorrow and see how it looks.
So far i have stripped off most of the paint and wire brushed the rust spots. At the rear where the front of the seat rests against the tank there are through holes and on the side, it hasn't broken through but the holes are quite deep in places.
Then I panel beat out most of the dents - some were easy are some were next to impossible, but we're getting there.
Next I tried bronze welding with a small tip and low pressure on the oxy torch and it looks like it might work. There's some shrinkage, so i have to be careful I don't end up with a tank full of lumps and dents.
But there's still too much rust on the inside for my liking, so I'll try to get it blasted tomorrow and see how it looks.
- Coyote
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- tz375
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Super rare? yes. It's the only one I have and it cost me nothing, nada, zilch, - apart from a small amount of time.
On this tank it might be possible to blast the insides - there is now a rather larger hole where the filler cap used to be. Into that hole will go the mounting ring from a 2007 GSXR750 (smashed tank).
I really don't want to spend heaps of money on repairing this tank, but I hate throwing things away that can be saved with a little work.
When I peered inside with a flashlight I could see that where I have bronze welded those low spots, they broke through and there's bronze on the inside too.
Peplacing the tank would probably be the sensible option but there's no guarantee that a replacement won't also have rust problems. I should have mentioned that this is the third tank so far and they have all had problems. Maybe if I spent more on a good tank I could save time and money.
On this tank it might be possible to blast the insides - there is now a rather larger hole where the filler cap used to be. Into that hole will go the mounting ring from a 2007 GSXR750 (smashed tank).
I really don't want to spend heaps of money on repairing this tank, but I hate throwing things away that can be saved with a little work.
When I peered inside with a flashlight I could see that where I have bronze welded those low spots, they broke through and there's bronze on the inside too.
Peplacing the tank would probably be the sensible option but there's no guarantee that a replacement won't also have rust problems. I should have mentioned that this is the third tank so far and they have all had problems. Maybe if I spent more on a good tank I could save time and money.

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- Road race school
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- To the on ramp
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Richard,
Sorry, you got the best tank I had left in my pile!
You could line the tank and then fill and finish the exterior with bondoglass or the like. As long as the liner is solid you shouldn't have a problem and since you weren't trying to save the original paint you have nothing but options.
Thanks for shopping!
John
Sorry, you got the best tank I had left in my pile!

You could line the tank and then fill and finish the exterior with bondoglass or the like. As long as the liner is solid you shouldn't have a problem and since you weren't trying to save the original paint you have nothing but options.
Thanks for shopping!
John
My bike is a "bighole" I keep throwing money into, so I had to get another!
09 Aprilia RSV1000
73 gt750
77 gt750 cafe
73 gt550
74 RE5
09 Aprilia RSV1000
73 gt750
77 gt750 cafe
73 gt550
74 RE5
- tz375
- Moto GP
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- Joined: Mon Nov 03, 2008 10:47 am
- Location: Illinois
Thanks for all the offers guys. It's a GT750 A with a 72-75 tank because I prefer the shape of the earlier tank.
I'm going to push on. It's all a great learning experience. I have repaired aluminum tanks before, but I can usually cut the bottom out to get to teh damage and that's not too hard.
I once had a TZ tank that a PO was trying to modify to fit something else, so I got it in three bits - A bent top shell, bent tunnel and a distorted bottom and it came out OK in the end.
This time I didn't want to cut it open anymore than I had to. I'll keep going and see where it takes me, but I see POR15 in my future!
I posted progress to date at:
http://www.pinkpossum.com/GT750/phattrakka2/Tanked.htm
I still have no idea if the bronze welding is the right way to go or if I should be using something else at a lower temperature to minimize distortion and shrinkage.
I'm going to push on. It's all a great learning experience. I have repaired aluminum tanks before, but I can usually cut the bottom out to get to teh damage and that's not too hard.
I once had a TZ tank that a PO was trying to modify to fit something else, so I got it in three bits - A bent top shell, bent tunnel and a distorted bottom and it came out OK in the end.
This time I didn't want to cut it open anymore than I had to. I'll keep going and see where it takes me, but I see POR15 in my future!
I posted progress to date at:
http://www.pinkpossum.com/GT750/phattrakka2/Tanked.htm
I still have no idea if the bronze welding is the right way to go or if I should be using something else at a lower temperature to minimize distortion and shrinkage.
- Suzukidave
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- Suzukidave
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