Cleaning fuel tank.

[Kiwifruit]

Gentlemen your advice please. I have a Kawasaki W650 that belonged to my late father in law. Since getting the 14 in 2014 the W650 has had very little use. None In the last couple of years.
Recently bought a new battery and thought it time I got it up and running again. Need to do fork seals, kit the front caliper oil change etc.
When I put it away I filled the tank with fuel. Went to drain it out last night and found some of the fuel had evaporated leaving the the uncovered inside of the tank to get rusty and dirty. Heaven knows what crap they put in the fuel here. Have sluiced the fuel around thinking it would wash out. Not so.
So what to you blokes do to clean up the inside of the tank. The old fuel is well stale, am just going to throw it out. I look forward to you suggestions.
Cheers.

[grog]

Have a google Col, lots of theories. I like the vinegar option, and also the sealing with kero or diesel. My 2 bobs worth, make sure after you fit in line filter. I once cleaned out old Ducati tank, i reckon that filter kept collecting crap for 10 yrs later.

[KiwiCol]

 Ya wanna talk to that guy from Omok Pannel & Paint Col,  he could probably make ya a new one, sure he's got an English Wheel there . . . 

[Kiwifruit]

Na Col he's the fella that let it get rusty in the first place. Looks like I've put a handful of brown dirt in there.

[Teufel]

https://www.kbs-coatings.com.au/product/rustblast/

https://www.kbs-coatings.com.au/product/motorcycle-fuel-tank-sealer-kit/

This has worked well for me in the past.

[Irish in Oz]

I use Phosphoric acid on my classic bikes, it's also good for brightening nickel and chrome. It can be diluted, it's the main ingredient used in alloy wheel cleaners.

[Irish in Oz]

Another method is to use Molasses if you are not in a hurry, could take a couple of days or a couple of weeks pending the amount of rust. I will be using this method in the near future on a Superdream tank, already done some brazing on the underside now to clean the inside will probably be a couple of week and hopefully no pin holes.

[gsxbarmy]

https://www.classicbikehub.uk/Workshop/article/petrol_tank_cleaning_and_rust_removal

[Irish in Oz]

Be careful with the stronger acids or alkalines, unless you are doing a full respray.

[Snapey]

Be careful with the stronger acids or alkalines, unless you are doing a full respray.

Irish is the expert on petrol tanks but he did fail when he thought a tank full of diesel would make the bike go better. 

[Irish in Oz]

@Snapey
Maybe the 1400 tank will never rust, btw its sitting 4 years now and will probably sit another 3. Time will tell now well it holds up. I've seen a lot of tanks ruined with fuel left in them, mine was left totally drained, and I dont leave fuel in carbs.

[Snapey]

I've seen a lot of tanks ruined with fuel left in them, mine was left totally drained, and I dont leave fuel in carbs.

Totally agree with draining carbs but don't they say to have the tank full? I'm inclined to agree with you on draining the tank but I'd be replacing the fuel with a good amount of oil.

[grog]

I agree on carbs, i always run to empty. Mowers, snippers, chain saws etc.

[Irish in Oz]

I coated the inside of the tank with Lanox.

https://www.inoxmx.com/products/mx4-lanox-lanolin-lubricant/