INSIDE the motorbike tanks.......????

[Motu]

Since when is inert gas expensive? - stuff it over the exhaust pipe of a car and fill it with CO2 yourself.Just make sure the choke isn't on or else you may put some unburned fuel in as well.

[Charlie]

maybe you could put a nice sticker over it...............
My tank is dammaged a bit more than that because it got the "chippies" from the road as well.

Thats cute... but I'm going for the minimalist uncluttered look!
Gonna do my best NOT to let my bike get road chippies... cause that would involve me getting up close and personal with the road too, and its not high on my to do list at the mo.

[Coyote]

Since when is inert gas expensive? - stuff it over the exhaust pipe of a car and fill it with CO2 yourself.Just make sure the choke isn't on or else you may put some unburned fuel in as well.

Somewhere along the line I got the impression that it was expensive

Good idea, have to try that

[vifferman]

I googled up defumigating tanks and read from another forum use washing powder and hot water and flush it out a few times. It worked and it didn't ignite when I threw a match over the tank from a safe distance huddled behind a car with a fire extinguisher at my side, but it's left the inside covered with surface rust.

Well it would do that - washing powder's usually caustic.

[HenryDorsetCase]

my CB400F tank had 28 years worth of rust and shite rolling round in the bottom of the tank when I got it. on the old bike board I frequent theres a bunch of different methods talked about. one is putting a handful of small nuts into the tank and shaking it, the nuts knock the surface rust off, and then it all pours out in the end.

one was posted by someone who might be an industrial chemist, and involved some shite you buy from a chemist.. Ill see if I can find it.

Most of them swear by a product called POR15 (its available here too). a three step process involving swooshing out the rust then a two pack stuff to line the tank.

I just cleaned mine out pretty thoroughly and now try and keep it full of petrol all the time so that the rust doesnt get a chance to form.

also I have a see thru inline fuel filter installed.

[HenryDorsetCase]

Remove the tank from the bike and remove the fuel. I find that lawn mowers can tolerate quite old gasoline!
Remove the fuel petcock from underneath the tank. The petcock will need cleaning but since it is made from aluminum the acid will harm it.
Stopper up the petcock hole with a rubber stopper. (better hardware stores will carry them). I would also clean the outside of the tank and put on a thick coat of automobile paste wax for protection. (leaking acid can cause damage)
Get yourself a pair of good rubber dishwashing gloves, goggles and perhaps even a rubber apron. While buying this protective gear, purchase a gallon of muriatic acid (really it is hydrochloric acid but this old name is what it is sold under) Also buy a large plastic drain tub that is bigger than your tank.
Find 2-4 cups of old nuts, bolts and screws!!? Pour the metal into the tank and then close the fuel fill cap and petcock hole. Now make like Ricky Ricardo and shake rattle and roll the tank. This will dislodge a lot of the rust and make the work of the acid easier.
Shake out the loose metal and save for the next tank. Pea gravel will also work but the sharp edges of the metal is more efficient. Flush the tank with water to remove any loose rust.
With the stopper in place, half fill the tank with water and place the tank in your plastic drain tub.CAUTION! Now pour in about one half gallon of acid. CAUTION This acid is hot stuff and you better protect yourself and the surroundings. Now fill up the rest of the tank with water. Don't let the acid run over the surface of the tank.
Let the tank stand with the fill cap open and check every 15 minutes on the progress of the acid. You will see that the rust will start to disappear and the gray metal beneath start to show. I have had tanks take from 1 to 4 hours depending on the level of rust.
When the job looks done, carefully remove the petcock stopper and drain into your plastic tub. Refill the tank with water and discard normally since the level of acid in this wash is very low.
Shake out as much of the water as you can and then pour in 1 - 2 cups of acetone. This will absorb any water and leave the tank when poured out.(place the acetone in a bowl and allow to evaporate)
Mix motor oil with gasoline, CAUTION, and rinse out the tank. A newly etched tank will rust super fast so a slight coat of oil will stop this action.
To neutralize the acid, pour into the tub marble chips that you can buy in a gardening store until the fizzing stops. Harmless carbon dioxide gas is given off.
Well, nobody said it would be easy! The commercial products work in the same manner but end with a coat of plastic.

Its from here

[Ixion]

Be aware though, that if there is significant rust, removing the rust may leave you with a lot of holes in the tank!. It is very hard to remove rust without removing some metal also. And if rust has eaten almost all the way through the metal, the rust removal may also take out the last thin skin of metal. Hence, holes. Better to find out about them now than later!