Topic: CB 750 Gas Tank restore: To seal or not to seal?

[umlaufa1]

I am trying to restore a '78 gas tank. The tank had no leaks and started out with moderate rust. I plan on painting tank after I get rid of internal rust. Here is what I have done so far..

• Place pea-gravel and nuts/bolts in the tank and spun for about 15 mins
• Placed 4.5 gallons of white distilled vinegar in tank for 24 hours, rotating tank every 8 hours
• Neutralized acid with banking soda / distilled water and flushed multiple times with gas.

This has removed 90% of rust although some still remains. Should I proceed with sealing the tank or not? There seems to be both a stigma for and against tank sealers.

[750K]

Don't seal it unless its leaking, keep soaking it in vinegar till its rust free. It will get it all out eventually, took two weeks to get my kz1000 tank clean and it was brutal... I got almost half of a pint glass of rust flake out of it. No pinholes so I won't be lining it anytime soon.

[750K]

Vinegar will only eat through if its already rusted to the point of pinholes, it a very mild acidic solution. Now if you left toilet cleaner in there for days you'll have a problem, check the vinegar every couple hours if you want but it's a waste of time. Check it every couple days and you'll be fine.

[seanbarney41]

theres not a thing wrong with a properly installed liner.

except that it still might fail

[billingstitan]

Can only speak to Caswell's - works great, even with some rust present. I recommend the dragon's blood so you clearly see coverage of the tank as you apply. I've used it twice and have never had any issues. One tank is going on 3 years.

You have to be totally OCD about prep - can't speak to other liners, but I believe that with Caswell's two-park epoxy, most problems are due to improper or rushed preparation. Tank must be totally dry - but if there is enough rust in the tank that a proper cleaning will not remove it, then Caswell's is a good choice, as it is designed to work with rust present (obv not flaking rust, but pits, flash rust, etc. help the epoxy bond to the interior of the tank).

If I had ANY concerns about existing rust in a tank - especially if it might develop into a pin hole - and even MORE especially if I was going to spend time and/or money for paint, then I would use Caswell's.

All that said -- my preference is always NOT to seal a tank unless necessary. It's a PITA. Just keep the bike topped off with 91 octane and run often and don't give rust a chance to develop.

But it can be tough to find a decent tank without rust issues on these older bikes, so sometimes a liner is the last best option - in which case, IMHO Caswell's is the best product out there by a wide margin, based on personal experience and lots of research.

[flybox1]

Fill it with golf balls.
Pour in jug kleen strip prep n etch. 
Top off with water.
Come back in a few hours, drain, rinse, rinse w acetone, and fill w gas.
Done.

[Airborne 82nd]

Like others have stated PREP PREP PREP This is the one thing in the process of any of the liners that make it work or not work. I know of tanks that I have done that have 15 years now and have no leaks & no signs of liner failure. These are 1950 to 1960 cars and trucks with 15 to20 gallon tanks . I have never used any thing but Por-15.

[AJK]

Should be a pic here of my tank lined with POR15.
http://forums.sohc4.net/index.php?topic=133734.msg1502750#msg1502750

I'd do it again.