Topic: Tank Empty for Painting, How to Keep Rust At Bay?

[Popwood]

Emptied and removed the tank today in preparation for a paint job. The interior has rusty spots, sort of like a moderate case of acne inside. Suggestions on keeping it from getting any worse over the next few weeks while in rehab? And what is the technique for removing these spots/abrading the rust? Think I've read here there's a common material you put in the tank and give it a good shaking?

[brewsky]

Put a handfull of nuts in and shake like crazy, preferably ones with the star washers attached.
OR you can do electrolysis to get rid of the rust, then the nuts.
Do a search for electrolysis and you will find several hits.
Also I believe Harbor Freight sells a rust removal product that has good reviews.
To prevent re-rusting, spray with WD40.

[OldSchool_IsCool]

fogging oil and roll/rotate the tank to coat the interior all over.  2-cycle oil is another good alternative.

[fmctm1sw]

lots of posts and opinions on tanks.  I'm preferential to toilet bowl cleaner and immediate sealing with POR-15 or the like... 

[78whiteorbs]

Take it from me do not paint your tank before cleaning sealing your tank . Cleaning a freshly painted tank is scary, one slip up with the chems and all you hard earned money and time are flawed/

[Popwood]

+1 on taking care of the inside before working on new paint. I'll be looking into the POR15 treatment or some such. With the tank off and completely empty I'm really surprised at how light weight it is. And this leads me to heightened concern about the how those small, but numerous rust spots can easily eat through such thin metal.

[fmctm1sw]

And this leads me to heightened concern about the how those small, but numerous rust spots can easily eat through such thin metal.

Toilet bowl cleaner will find those weak spots... trust me....  If you use it, dilute it with water.  I noticed a 47-50mm freeze plug from autozone fit perfectly into the mouth of my 350F tank.  Dont know what your tank is off of but it worked real well for me.  No leaks...

[Popwood]

After searching I see there have been many POR 15 and Kreme jobs done, often with a lot of stress and frustration. Also see an interesting post from greenejeans after he stripped the Kreme from his tank:

 After that, I put an old bicycle chain in there with some simple green and shook it for what seemed an eternity - that took care of most of the rust.  Then, I put 2 bottles of " The Works " toilet bowl cleaner (you can get it at wal-mart for $2 a bottle) and swished it around - let it sit while rolling the tank over periodically.  After that, it look BRAND NEW, and I mean brand new.  I immediately rinsed with water and some baking soda and a little gas with some 2 - cycle oil in it and shook it around until everything was coated, dumped it out and then blew it out with my air compressor followed by several hours with the hair dryer.

I'd say this is an argument for rust removal and not coating. Has me wondering what direction to take on this 750 tank.

[fmctm1sw]

Yeah but be careful with that toilet bowl cleaner, it will eat pinholes in your tank if there are weak spots.  I was never able to find anything to make it not flash rust after using the stuff.  I eventually dried it with a hair dryer real good and sealed it...

[HondanutRider]

I concur about the problems keeping rust a bay after cleaning it out with an acid wash.  I had my 350F tank spotless clean after a scour using muriatic acid, which worked really well at cleaning out the rust.  However, even after trying to seal it with oil and keeping it full of gas, it still quickly rusted up - so bad that the fuel flow is minimal with the inline filter and the bottom of the petcock is plugged so that there is no flow at reserve.

Yesterday at the motorcycle show I talked to a chap about his 1970 Suzuki on display, and how he had cleaned the tank rust with phosphoric acid.  This acid apparently leaves a phosphor coating that protects from rusting again.  I can attest that his tank internal looked pristine and had a nice grey coating that looked like a new tank.  I don't know how bad or good his tank was when he started, so maybe his treatment isn't suitable for all.

For my own assurance, I'm going to strip my tank again, using some of the treatment POR-15 provides, and then I'm going to coat it with their tank sealer.  I've used their tank sealer before on other tanks, and I have been happy with their results.  I already know this 350F tank has a pinhole leak that I plugged, and the POR-15 does seal those as well as help to prevent the rusting.

[fmctm1sw]

I already know this 350F tank has a pinhole leak that I plugged, and the POR-15 does seal those as well as help to prevent the rusting.

My kit shipped with a small chunk of patching material and a foam brush I never used too..

[Popwood]

So where did you guys buy your POR 15. I see they sell direct and have a cycle kit. I'm wondering if cycle shops or Pep Boys or Autozone might stock it.

[OldSchool_IsCool]

I know my local Kaw/Yam shop carries it.  So does at least one local independent guy.

[fmctm1sw]

So where did you guys buy your POR 15. I see they sell direct and have a cycle kit. I'm wondering if cycle shops or Pep Boys or Autozone might stock it.

I think their website.  Somewhere around $50 for the cycle kit.  In another post I wondered if one could just strip with toilet bowl cleaner and go right to the sealant.  I bought a can of sealant but didn't get to try yet with a spare tank I have.  

[HondanutRider]

So where did you guys buy your POR 15. I see they sell direct and have a cycle kit. I'm wondering if cycle shops or Pep Boys or Autozone might stock it.
I bought my first kit direct in Canada from the supplier whom I believe is mentioned in their wesite.  Right now my local parts jobber is getting a tin of the tank sealer for me - they don't stock but can get it direct, likely from my first supplier.

I think their website.  Somewhere around $50 for the cycle kit.  In another post I wondered if one could just strip with toilet bowl cleaner and go right to the sealant.  I bought a can of sealant but didn't get to try yet with a spare tank I have.  

You can probably just strip with the toilet bowl cleaner as the POR-15 stripper mentions that they leave a desirable phosphor coating for better adhesion, and the toilet bowl cleaner is part phosphoric acid, I believe.  Just wash it out well after its use, and make sure the tank inside is perfectly dry before you apply the POR-15 sealer.  It needs to be done relatively quickly, as the stripped metal will likely start flash rusting right away.  I think however the POR-16 is supposed to bond to some amount of rust.

[Popwood]

Thanks, everyone, for the input. I'll call around tomorrow to see if I can pick up locally. Those shipping charges add up, and if it's coming from Canada, could take awhile going through customs, etc. Not that I'm in such a hurry. It is mid-January here and riding days are infrequent. I did move my windscreen off the 750 (along with the tank for painting) and put it on the 550 so I can at least get a short ride when a decent day comes along.

[fmctm1sw]

You can probably just strip with the toilet bowl cleaner as the POR-15 stripper mentions that they leave a desirable phosphor coating for better adhesion, and the toilet bowl cleaner is part phosphoric acid, I believe.  Just wash it out well after its use, and make sure the tank inside is perfectly dry before you apply the POR-15 sealer.  It needs to be done relatively quickly, as the stripped metal will likely start flash rusting right away.  I think however the POR-16 is supposed to bond to some amount of rust.

I read that part about the stripper and phosphor coating somewhere too.  I think that's what may have given me the inspiration to just put the toilet bowl cleaner in there and seal it.  You're right, I specifically remember the instructions mentioning that it will seal over the slight flash rust.  Make sure it's real dry though.  I'll get around to trying it sometime.  I have a sweet spare tank, no dents or nothing (not original paint unfortunately though)

[78whiteorbs]

I am sick of working on tanks, with chemicals. Next time I think I am gonna take mine to a radiator shop and pay them to coat it . Done and done.

[MickeyX]

I am sick of working on tanks, with chemicals. Next time I think I am gonna take mine to a radiator shop and pay them to coat it . Done and done.

Hmmm, we did that with Kit's original tank on her CB650. They left it in so long that they ate off all the threads on the petcock and where the tank badges bolt back on and the paint was a total goner. You couldn't even tell what it started out as because the whole thing was total rust on the outside. They cut huge holes in the bottom and welded it back up. They put in redcoat (that was actually blue) and it ended up rusting all over anyway and was useless. All of that cost us around $220 (+ buying another tank) to learn to do it ourselves or buy one that is in good shape already. Good luck. 
We're using molasses on one and The Works on another to see which we like better. Either way, a little flash rust is better than what I have now and if I don't get it right the 1st time, it only cost me $5 per tank to try again and perfect it.