Kawi2strokes.com Forum

For those that have acid washed the gas tank what did you use to seal the openings and how much acid wash did you use in each treatment?

I know Evapo rust is the most recommended but all I could find was Prep and etch , a little testing on a some rusty hardware showed good results...

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1975 S3 project bike
1974 H1 project bike
1972 Yamaha R5
1974 Yamaha RD350

Jack,

I have used a couple of products to etch the tank. I haven't used it but Evaporust is probably very good. I used one of those plumbers test plugs from the hardware store to seal the filler hole. I can't remember the exact size but you can measure the opening and go to the hardware store and find the right one. It looks like this and can be tightened with a wrench.

I used a rubber stopper that fit the hole where the petcock goes. It worked great. This will work better if you shake the tank now and then and leave it in different positions - up, down, left, right, etc. For thick rust you will need something to scrub the inside. The best I have come up with is about 4 feet of steel chain. I used light weight stuff that goes on a swing set. With this in there, when you shake the tank it scrubs the corrosion and allows the etch to penetrate quicker. Since the chain is all one piece, all you have to do to remove it is to hook one link and pull it out. I have used screws in the past and that is plain stupid. Live and learn.

Tank Before:

Tank After:


As others have stated, once the metal is etched it will rust very quickly. Drain, flush with water, drain, then flush with alcohol to drive the moisture out. I filled mine with gasoline and put the stoppers back in. That was about 6 months ago and I hope it is still clean when I need to use it.

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Rotortech
Indianapolis
1974 S3

Kevin, good post thank you The expanding plug is a good idea I will try that .

I have 2 gallons of acid figuring I'll put it in an slosh it around for an hour or so then drain.

My tank has mega heavy rust on the inside out side looks darn good, I put 20 3/4 nuts inside and broke down the heavy scale, its so bad that there is a possibility that the acid might eat right thru the tank ..

Thanks

_________________
1975 S3 project bike
1974 H1 project bike
1972 Yamaha R5
1974 Yamaha RD350

Jack,

You just have to let the acid do the work. It really doesn't attack the parent metal (much) but will eat the rust quickly. If you end up with pin holes it is because they were rusted through already. Then you just have to coat the inside of the tank.

I used one or two gallons - I forget. The tank was not full. I kept shaking it and repositioning it over a 2 day period. Take your time and let the acid do the work.

Good luck on that one.

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Rotortech
Indianapolis
1974 S3

Will do same two days, thanks

_________________
1975 S3 project bike
1974 H1 project bike
1972 Yamaha R5
1974 Yamaha RD350

I would throw Some mixed fuel in it for storage. My Honda scrambler flashed a little where the fuel wasn't up to the top after basically the same treatment. I used vinegar for the heavy lifting, KREEM brand acid for the rinse. I was then supposed to do the epoxy liner routine but i couldn't bear to pour it in the tank!

Good suggestion on the fuel/oil mix.
Actually, the best way to store the tank is to fill it with oil to the very top. If I have to clean mine up again, then I will do that.

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Rotortech
Indianapolis
1974 S3