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Hi folks, while cleaning up the underside of my project CB200 tank I found a few solder and bondo/putty patches from the previous owner. A wire wheel popped off one of the patches so I’m assuming the others are weak bonds as well.
Friend is a professional pipe fitter with decades of brazing experience and can patch them easily and safely.

Are there other avenues I should consider before putting an acetylene torch to the tank?

thanks
313102
 

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Hi folks, while cleaning up the underside of my project CB200 tank I found a few solder and bondo/putty patches from the previous owner. A wire wheel popped off one of the patches so I’m assuming the others are weak bonds as well.
Friend is a professional pipe fitter with decades of brazing experience and can patch them easily and safely.

Are there other avenues I should consider before putting an acetylene torch to the tank?

thanks View attachment 313102
I would make sure there are no fuel vapors left in the tank by washing thoroughly. Make sure to leave fuel cap OFF and let your welder have at it. Good luck!
 

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It would be wise to have an expert take care of any holes. Looks to have rusted from the inside. You may want to try to find any soft spots at low points in tank where water can collect, and have your friend repair any more damaged spots that may be found.
A good preventive measure to reduce or stop future leaks would be seal inside of tank with one of the products available to deal with rust and leaks. I have had good luck with "Kreem", but I expect some may say other products are better. Anything that puts a coating inside the tank will help. Good luck, HondaJohn
 

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Brazing is too high of temperature for that repair. The metal is thinned out to the point of needing a patch.
I use 6% silver bearing solder and liquid Tec Flux along with a sheet metal patch for that kind of repair. I do have a regular oxy/ace set up and a jewellers oxy/ace set up but find a regular propane torch gives enough heat for the job.

I tin both pieces then simply lay the patch on and heat it up. You can do this with regular solder and flux as well.
 

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All good advice ! I tap the hole inwards till good metal is reached and use a normal solder , it's surprising strong and bonds well , then can be filed flush , if it's a huge hole then have your welder patch it . Regards Will
 

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Hi folks, while cleaning up the underside of my project CB200 tank I found a few solder and bondo/putty patches from the previous owner. A wire wheel popped off one of the patches so I’m assuming the others are weak bonds as well.
Friend is a professional pipe fitter with decades of brazing experience and can patch them easily and safely.

Are there other avenues I should consider before putting an acetylene torch to the tank?

thanks View attachment 313102
All good advice ! I tap the hole inwards till good metal is reached and use a normal solder , it's surprising strong and bonds well , then can be filed flush , if it's a huge hole then have your welder patch it . Regards Will
Sounds like good advice, to fill depression with solder and smooth it. I haven't have good luck with using gas proof fiber glass to make patches. Afterwards I coat the inside of the tank with sealer to make sure tank doesn't leak. For larger holes you might have to use a torch and braze a patch and then use solder.
 

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Hi folks, while cleaning up the underside of my project CB200 tank I found a few solder and bondo/putty patches from the previous owner. A wire wheel popped off one of the patches so I’m assuming the others are weak bonds as well.
Friend is a professional pipe fitter with decades of brazing experience and can patch them easily and safely.

Are there other avenues I should consider before putting an acetylene torch to the tank?

thanks View attachment 313102
I had a similar small rust hole in a lower tank corner. I was in not in a position to do a metal repair of any kind and ended up using JB Weld. This worked great. The same tank was "kreamed" later so it's hard to say if this would have lasted but I'm sure JB Weld is as gasoline resistant as Bondo, but more stable over time. Bondo is basically polyester resin with fillers. Nothing wrong with polyester resin as we know that some Italian Makers made fuel tanks out of fiberglass, using polyester resin of course.

emdude
 

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With my first cd175 when I rode it home I filled with petrol and it went everywhere! The seat had rubbed through the rear of the tank , I bought some gum chewed it and filled it with that, it lasted till I got home . When I got back I propped the tank up still with a good amount of fuel , emery'd the area and spread araldite over it , it was still working when I got rid of the bike , wonder if it's still on?😃
 

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I have repaired several tanks and carburetors with JB Weld. Never had a failure. All of them are still going strong. However, I do have a guy that can cut a tank (fender or any sheet metal part) apart, cut out the rust, weld in patches, work out all dents, and weld them back together and you would never know it was done.
TOOLS
 

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I've had good success roughing up and cleaning the surface with acetone then pouring a thin layer of JBWeld thinned with acetone. Dry time is several low humidity days at room temp for a 1mm coating (or set the tank inside a cardboard box with a 100w droplight bulb for a day) then subsequent layers can be added if needed. I'd bet the addition of steel mesh (like water faucet diffuser discs) would further strengthen the repair.

My experience was with a side pinhole where fuel had blistered a PO's Bondo patch.
 
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