I clean the tank out with 200 sharp screws and shake it about each time i go near it so in a week it just has a lot of dust and screws inside. Empty it out and rinse with petrol/white spirit or whatever you have. Then just use the tank and add a tiny bit of 2 stroke oil each fill to leave a little coating of oil swishing around. I used a liner just once and clogged up my carbs so never again.
Caswell is supposed to be a good one though.
If it gets a hole at any point, i weld it up.

 

I used Rambo's method but with a proprietary de-rusting solution (H7) here in the UK. Worked very well. Used Caswell to seal a small weep in my Tiger 750 tank, and to line my Daytona tank - which sat unused for 37 years! Did not want to risk weeps in a very expensive new paint job. Both tanks have been in use now for 4 years with no known issues. The Caswell product sets very hard and seems very stable.

 

Thanks rambo and andy for your good suggestions. Will go ahead with the cleaning then flush with some Bicarb Soda and finally with a little two stroke mixture for some lining.
Cheers

 

Doing tanks like this, i still get no clogging of the carbs even without a fuel filter. All i have is the small mesh ones in the carb unions

 

talking with a mate yesterday and he suggested a method i'd not heard of before: remove the fuel tap and seal the fuel tap outlets with plugs, put a few handfulls of road base/blue metal in the tank with your preferred liquid, put the fuel cap on, wrap the tank in an old doona or similar, then put the wrapped tank in a cement mixer and pack it so it won't move, then turn the mixer on - at first i thought he meant a cement truck, but no, he meant one of the portable ones that builders use
sounds pretty agricultural, and you need access to a cement mixer, or a truck

 

Yes. There is a youtube video on this and in theory it should work as well.
Cheers

 

Hi jhang, My personal experience is once tank begins to rust it will continue to rust unless sealed. Especially above the fuel level.

It doesn’t really matter how you remove rust. I’ve used sheet rock screws, nuts & bolts, various “rust remover acids”.
If you shake tank too vigorously with screws etc you can get small dents.
The acids do a very good job. I’ve observed rusting up to & including rust perforation. In my area it is 100% certain to rust with our E10 fuel.

Caswell is very reliable at sealing rust perforation. Sealing & stopping surface rust that has been cleaned with screws etc. Use acetone as final rinses before sealing.

Follow Caswell instructions exactly. Don’t skimp on sealant size. The small can on paper might be enough, but it is very easy to get holidays in coverage. Larger containers make full coverage much easier. This is especially important on later tanks with the tube down the center fro mounting bolt.

In my estimation the big problem with future rust is, you spend time and money on nice paint work. The rust perforation happens, damaging paint from underneath. Now you’re needing to seal or replace tank & repaint. I’ve seen this several times.

Caswell sealant formula is same as our steel underground fuel tanks are lined with. It is very fuel proof even with high levels of ethanol.

My Caswell shows zero deterioration after 6 years.
Don

 

Hi jhang, My personal experience is once tank begins to rust it will continue to rust unless sealed. Especially above the fuel level.

It doesn’t really matter how you remove rust. I’ve used sheet rock screws, nuts & bolts, various “rust remover acids”.
If you shake tank too vigorously with screws etc you can get small dents.
The acids do a very good job. I’ve observed rusting up to & including rust perforation. In my area it is 100% certain to rust with our E10 fuel.

Caswell is very reliable at sealing rust perforation. Sealing & stopping surface rust that has been cleaned with screws etc. Use acetone as final rinses before sealing.

Follow Caswell instructions exactly. Don’t skimp on sealant size. The small can on paper might be enough, but it is very easy to get holidays in coverage. Larger containers make full coverage much easier. This is especially important on later tanks with the tube down the center fro mounting bolt.

In my estimation the big problem with future rust is, you spend time and money on nice paint work. The rust perforation happens, damaging paint from underneath. Now you’re needing to seal or replace tank & repaint. I’ve seen this several times.

Caswell sealant formula is same as our steel underground fuel tanks are lined with. It is very fuel proof even with high levels of ethanol.

My Caswell shows zero deterioration after 6 years.
Don

Thanks Don for your good suggestions. Will have a think about sealing after all.
Cheers

 

I have seen and welded a few tanks and the rusting has increased a lot with the E5 added now. Most of the rusting is going on inside of the top surface of the tank where the air space is. Once the top begins perforating, it becomes a lost cause and usually a replacement tank is a better option. I have just bought 2 Indian made steel tanks and they cost less than a 50 year old rusty one now and they will not leak for many years.
Since adding a little 2 stroke oil to my various petrol tanks, none have leaked or perforated again.
If you did find a good sealant and followed all the instructions, it might last quite a few years. As Don has indicated, painting a tank can be very expensive.
I still prefer no sealant at all. I have 5 spare tanks because i change them around on the bike. In storage, i just add a little engine oil and let it run around the whole tank. Years later i can refit it knowing it will still not have rusted any more.
Never just leave a tank empty in storage. It has to have some preparation. Plus wrap it up to prevent temperature change condensation

 

Electrolysis is another option for dealing with the rust prior to sealing. It converts the rust to black iron oxide. It can be done by filling the tank to the brim with the electrolyte and inserting electrodes through the filler hole.

It is pretty much a line of sight process so an electrode will be required either side of the tank tunnel, thick steel wire is ideal for electrodes.

I have had a lot of success using electrolysis on de-rusting corroded bike parts over the years. It is simple to do, just needs some care and readily available bits and pieces.