Welding help with fixing this tank

[RD350]

Gentlemen:

Greetings! I need to fix this gas tank. Please see attached pictures. Got it cleant and sand blasted.
New is not available anymore, so its out of the question. Getting a used one is next to impossible.
So is this repairable? Can any experts help me here? I am willing to ship the gas tank from here in Canada to your location. Appreciate your help.

regards,

Daryl



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[Robby321]

What bike is it off? That tank looks pretty well gone to me..

 

[ttpete]

What bike is that for?

If you have it blasted inside, the only thing I can think of is to tape over the biggest holes and treat the inside with Caswell epoxy sealer from Caswell Plating Co. The metal is going to be so thin in the bottom from corrosion that you'll just burn it up trying to weld it.

If you use 2 coats of sealer, it will strengthen the metal because it sets up hard.

 

[gofastwclass]

Looks to me like a custom tank may be in your future. By the time someone finishes chasing all the holes and thin bits of metal in your current tank they could (and probably would have) fabricated a new tank.

On the positive side of the coin, at least you have a good template.

 

[EdT]

How much of that tank is cosmetically important and how mush is hidden when installed? Are there holes on the top side of the tank around the filler neck or are those just external pits? In any case, it probably can be fixed, but it'll be pretty expensive IMHO. If there are any decent used ones around, that would probably be cheaper. If they're all like the one you have, it's a different story. The epoxy sealer mentioned above could work, but it doesn't look like the metal on the bottom is very sound so that too is a bit of a **** shoot.

 

[RD350]

Thank you all for your input/advise. This gas tank is of a 1981 Yamaha RD350LC that I am trying to restore......

 

[countryroad82]

Were it me I would find a better tank. That thing is pretty far gone to wind up fabricating the whole thing from patch panels and welding wire.

 

[ttpete]

Thank you all for your input/advise. This gas tank is of a 1981 Yamaha RD350LC that I am trying to restore......

There's a place in the UK called Yambits that everyone there uses for older Yamaha parts. Their page features an RD350LC.

https://yambits.co.uk/

 

[Robby321]

What bike is it off? That tank looks pretty well gone to me..

OK, I looked now screen name. Should have caught the "RD 350"! Should be way more parts out there F/S. just gotta find it. Watch Ebay, etc. and use the search engine.

Damn, heres what I found quick..

https://www.google.com/search?client=firefox-b-1-d&q=Yahama+RD350+1981+gas+tank

 

[joeswamp]

I'd say that's a template for a newly fabricated tank ... if the bike was really old, rare, or exotic.

But your bike is none of those. I'd be searching motorcycle junkyards or eBay. I almost bought an RD350 once, those things are so much fun.

Incidentally, how did the tank get that rusty? That's a pretty bad one, looks like it's been exposed to saltwater.

 

[txvwnut]

Get on eBay there’s a few tanks on there for your year range RD. They ain’t cheap but they’re right around or less than what you’d pay to have that one repaired.

 

[shawnspeed]

Find a new one... that ones a safety hazard when fixed...ebay is your friend..

 

[SlappyWhite]

That tank is too far gone to repair. You have rot holes top and bottom and the metal between the holes is likely very thin. Find a better tank.

Could be used as a template or mold to make your own... but that is not easy of course.

 

[gorilla]

If I had to repair that tank I'd use soft solder. I'd tin the areas that needed a patch, tin the patch piece and sweat them in place. The smaller pits could just be filled with solder. This would be done with a big electric soldering iron not a torch and 50/50 solder and liquid acid flux. I would then have the tank lined with one of the tank sealer products. This would be a frustrating job but I feel it's doable. Painting the tank after this might have a few challenges.

 

[RD350]

Thank you Gorilla for your guidance, this is much appreciated.
I will give it a short.
These tanks are not even available on Ebay as they are for the liquid cooled RD350LC not the RD350 air cooled motorcycle. Thanks once again to all for your input, much appreciated.

 

[rsanter]

If you had to repair that one I think welding is out of the question, the welding will do more damage to an already bad tank.
What I would try is if the inside is clean/blasted. I would use automotive panelbond like used to adhere new panels on cars. Coat it on to fill the holes and a smear over the surface.
Sand smooth but don’t remove all from the surface. Kind of treat it like bondo and leave a thin coating over the whole thing.

Then take it in and have the inside lined with a fuel tank sealer, this will be the part that actually holds the fuel.

Prime, prep, and paint, then put it back in service.

Only other thing I could think of is to cut the bottom out and basically make a tank that goes into the tank and then use what you have as a cover of sort

Bob

 

[tarmy]

For race cars they have bladders you can install...not sure if that could work here...just an idea.

Also, those are the holes you can see...and that are present now...unless that tank is lined...it sure looks like it may develop more failures in the future...

Good luck OP...pics when done...

 

[Robby321]

If you had to repair that one I think welding is out of the question, the welding will do more damage to an already bad tank.
What I would try is if the inside is clean/blasted. I would use automotive panelbond like used to adhere new panels on cars. Coat it on to fill the holes and a smear over the surface.
Sand smooth but don’t remove all from the surface. Kind of treat it like bondo and leave a thin coating over the whole thing.

Then take it in and have the inside lined with a fuel tank sealer, this will be the part that actually holds the fuel.

Prime, prep, and paint, then put it back in service.

Only other thing I could think of is to cut the bottom out and basically make a tank that goes into the tank and then use what you have as a cover of sort

Bob

Agree 100% as been there done that....

 

[MP&C]

This shows how the tank halves (inner and outer) are welded together...

The next best thing for someone welding one themselves would be to form the same flanges, trim each to the same length, and TIG weld the bottom edges together..

The widespread damage shown in your pictures look like it would be a better option to make a new tank, using what you have as a pattern. Form each of the inner and outer half separately, then weld together..

 

[PugetDude]

Might be cheaper to buy an entire donor bike.
Labor to build a custom tank is going to be expensive
There are several RD-350's online under $750...

An RD-350 was the last motorcycle I ever rode. Light and REALLY quick.
Good Luck! Post pics of your solution.

 

[cooljoe57]

Thank you Gorilla for your guidance, this is much appreciated.
I will give it a short.
These tanks are not even available on Ebay as they are for the liquid cooled RD350LC not the RD350 air cooled motorcycle. Thanks once again to all for your input, much appreciated.

Quick search turned up a few of them on Ebay. Not exactly cheap, but ready to use and safe.

https://www.ebay.com/i/333097699194?chn=ps
https://www.ebay.com/i/333107341695...7&rk=1&rkt=9&sd=333097699194&itm=333107341695
https://www.ebay.com/i/132975036252...7&rk=3&rkt=9&sd=333097699194&itm=132975036252

 

[ttpete]

The last two are reproductions from India. I've seen some for Triumphs and Nortons, and those were pretty good. $400 isn't a bad price and seems to be average for these.