Topic: Oil Tank Blues......Definitely My Fault

[RRRToolSolutions]

Guys,

I basically put my riding on-hold during 2015 - less than 200 miles total for the year. Whereas I have averaged 10,000 miles and more each year for many years, last year I was bogged down with moving my home and business from South Carolina to Alabama (home for the wife and me where our aging family needed us to be) and building 3 new websites, new tools, and developing new products.

This year I want to ride. My 1974 CB750 hasn't been started in almost 2 years. I put a new battery in it last week and then checked the tank for oil only to find that my once perfect and rust-free tank was coated with rust above the oil level inside. I'm so glad I didn't start it and circulate the rust throughout the engine, but now I'm not sure what to do.

The tank is powdercoated and looks great on the outside, but I've got to purge the tank and it's internal baffling of rust particles. I've thought of removing the hoses after draining the oil tank and then adding vinegar for several days before flushing/rinsing. The idea was to leave it installed on the bike if can.

I'd love some inputs on how you guys addressed the same problem. Once cleaned, I promise to not neglect the old girl again - Thanks, Gordon

http://www.rrrtoolsolutions.com/articles/honda-1974-cb750-four-cb750k4/

[Don R]

 Sounds right. You could use one of the rust dissolving products too. Once the hoses are off it's easy to remove the tank, in fact you may need to remove the tank bolts to get the hoses off anyway. Cork the outlets and shoot the juice to it.

[strynboen]

flush inside in acetone..to get the oil film off..then the soaking vill Work on all areias inside the tank.
.rust is prob not under the oil level..but still..get  all kleaned up dont harm anything

[70CB750]

I would use gasoline myself, but I hear kerosine or diesel is safer 

[RRRToolSolutions]

Thanks for the inputs guys -

Gordon

[strynboen]

the acetone ,,vas only for remove oilfilm.
..to make the folloving klean prosess vinegar or a other rust eating fluid. Work effektive.they dont Work effektive if a oilfilm bloks for kontakt to the metall...
and yes it need to be netraled.. diesel is super fine  too flush

[edwardmorris]

I just had my oil tank powder coated too, and I'm having a similar issue. I had cleaned the tank and fogged it with some CRC and it was all good, except the PC shop washed it again and didn't fog it after drying it out. The rust isn't severe but I do believe I will have to get it out of there. I know Dwight recently cleaned out his gas tank with amazing results using "The Works" toilet bowl cleaner (phosphoric acid). Do you guys think that's too aggressive or should I just use it?

[Jerry Rxman Griffin aka MuthaF'er]

Take it off, as you know it's not THAT difficult. Don't even try to do it on the bike. That'd potentially open up a few can of worms Gordon. You have any specialized tools for the oil tank? 

[vames]

Just to correct -- The Works is hydrochloric acid and while it will remove rust (and metal) you will almost certainly get flash rust no matter what you do. You can buy phosphoric acid at paint stores or home depot and it will leave a protective layer.