Topic: CB 550 tank inside - what is this and can it be saved?

[Chaser60]

Here are a few pics of inside of 1975 cb550 tank.   Gas that came out is a little bit of a dark brown / redish color.   Cap is corroded.  Is this a coating of some kind and if so, what should I do with this before the tank goes out for paint?   

[calj737]

Looks like either REALLY bad gas or a liner that has gone bad. Yuk! Will any of it scrape off with a sharp screwdriver so you can be sure?

Either way, yup, gotta purge that before you send it out. If not, when you do go to remove it, you run the risk of damaging your paint. If it's rust, EvapoRust soak for three days, rinse, and re-soak. You may have to cycle this a couple of times to get a thoroughly clean tank.

If it's an old liner, then use MEK as a solvent. Nasty, odorous stuff, but it will purge that liner completely.

[sebastienb]

Is it red ? Looks a little like redkote which is a liner

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[Duanob]

I just went through this last summer. Even worse than your tank I had pin holes.

To remove the old liner, remove the fuel tap, put a couple of gallons of pure acetone in the tank and seal all holes completely. remember that using tape is no good as the acetone will dissolve it. I used a plastic wine cork shaved down to fit the fuel tap hole. Since your cap gasket looks old just use it to seal the filler cap as you will end up replacing it any way. I used a $8 morter mixing tray from home depot to set the tank in to keep from spilling on the ground. In the course of 24 hours or so turn the tank in varying angles so the acetone gets all over the inside and dissolves the crud completely. You might have to do this twice. Once your done do a mineral spirit rinse. You should be good to either reseal it or just derust it with phosphoric acid and use it as is. Remember that acetone will dissolve and ruin the paint if you want to keep the original so try and keep any spillage to a minimum and dispose of it properly.

[Chaser60]

As always,  thanks for your input.   I was able to peel a little of this off and I believe it is red kote.   Tank now has MEK in it as that is the preferred solvent for redkote.   I pulled the cap off (drilled the pin on one side) and used a 1 7/8 inch freeze plug.  (the kind you tighten with a wrench to expand).   removed the petcock and used a rubber plug there with duct tape to hold it in place.    Will see what it looks like sometime tomorrow or next day.   Will deal with rust and recoating after I see the progress on the coating removal.   Tank is to be painted once i have this all happy on the inside !

[Chaser60]

Well - again thanks to this forum, not only to those that replied to this thread but to the others that posted their processes to deal with tank coating and rust issues.   Here is where I am now - about 1 week later.

1 gallon of MEK used up.    As said above, plugged with freeze plug and rubber cork.   about 1/3 gallon MEK in.  let it sit, swish it around, leave tank in different orientations.   I did get some leak when left upside down from center of freeze plug, so dont recommend leaving it like that.   Just due to my schedule, it sat for 2 days in different orientations.   Poured it out, nasty red and stringy "skins"   Definitely red kite.    repeated this 2 more times over course of 5 or 6 days.

Didnt get a picture but most of the red kote was gone and by last 1/3 of MEK, the solvent was not coming out deep brown/red.

Next - Rinsed it with hot water over and over.  lots of the "skins" coming out and repeated until this stopped

Next - one bottle of the WORKS full strength.   let sit in different orientations and also swish the tank around and turn over and over....This sat for about 1 to 2 hours.   Poured it out and WOW it was really looking better.

Repeated with fresh bottle of WORKS and left it this time for about an hour.

Rinsed fully with warm water and baking soda.   Probably did about 4 to 6  gallons through the tank and used a heaping 1/2 cup of baking soda per gallon

One last rinse with warm water

drained all water then 1 quart of acetone which absorbs water very well.    drained it out and let it air dry 

At this time, I am not going to re-coat with red kote, or mist it with MMO or other oil.    If it flash rusts, I will rinse one more time with works and then red kote it.   

Before pics are up this thread.   Here is a couple after shots.

I think it looks pretty good, but am no expert.   Any thoughts or feed back on next steps are always welcome.

[seanbarney41]

looks great...I would swish it with MMM, wd40, or 2 stroke oil and call it good.  Probably not much humidity in the air in VA this time of year, but once it gets humid, it will rust if you don't have some oil coating or some gas in it.

[LesterPiglet]

It looks 100 times better than the tank on my bike at the moment.

[Stev-o]

Don't red cote it.  Looks like it came out pretty clean.

[calj737]

Bill - instead of using acetone to dehydrate the tank, use Denatured Alcohol. It's paint safe, evaporates almost immediately, and you can avoid flash rusting as a by product.

Btw- dropped my jugs to Andy the other day. Made him promise to coat mine before he did your frame ;-)

[reddyvv]

Amazing difference!!

[6adan]

Looks like whoever did the red kote did not clean it first. I have used red kote in several tanks and have had no trouble with it.

[Duanob]

Wow looks awesome! No need to coat it at all.

[AJK]

The before and after on your tank is excellent. I've got some spares to try that out on.

Also, if your considering lining the tank, POR15 is excellent stuff too. I've attached an example pic of my tank with POR15. My painter done this and prepped it up correctly. Its what he always uses. Its good stuff.

[Chaser60]

Thanks all.    I hear great things about red kote from many sources, so agree it was likely mis-applied or very very old.  Likely both.   No way for me to know.     will see how it looks in the morning and if its flashed, will clean it and use the alcohol and then fog it with MMO.   I would love not to coat this at all, but sure as hell dont want to repeat this week of nasty chem's especially after I have the outside painted.   

cal -  you're killin' me, but no worries,   Andy should definitely take good care of repeat customers(you)  that also give him referrals (me).   I cant wait to start putting this thing back together.

Cheers all

[calj737]

Bill - from the pics, you're tank is perfectly clean. Just rinse it well (as you've done) and either splash a tad of gas in it and then set aside in the house or warm garage until use. A liner is NOT required. Unless you've got some pinholes anywhere, no liner needed.

If you do line it, Caswell or POR-15 seem to be the most highly recommended. Ive used Red Kote and Caswell, both with equal results.

As for Andy, he's got a batch of Thermal Dispersion to do next week is only reason my jugs will pop in front. Your black batch is queued after the current load of thermals. He runs color and coating batches in series. Sometimes, you get to drop off on Monday and Tuesday he calls you back because you got in on a color or coating type run. Makes it a bit of hit-miss on lead times.

But, it's always worth it. His prep work and spraying is really top notch. He's not cheap, but he sure is good. Ping me when you head down, perhaps I can buy you a mug...