I have two xbr tanks I'm cleaning out at the moment. One is real rough inside, so I soaked it in soda crystal solution for the max recommended of five days, agitating every so often. I then rinsed tank. Not impressed, it didn't really work. Though there are big flakes of tank sealent in the tank.
Should it have dissolved these?
Does ambient temp play a part?
So im repeating the process, but with the tank in the house rather than a freezing shed

Other tank has had some serious welding on the underside in a previous life, butt appears to have some light rust inside. So I started with stage 2, the recommended Spirits of Salt. Nobody I asked had heard of this stuff. It turns out to be the ancient name for hydrochloric acid at 30%. Instead of diluting it as recommended, I just used brick clean neat, which is 11%. Well impressed, totally removed any rust.

After a good rinse, then went to stage 3, phosphoric acid. This is the main product in a lot of rust converters, and basically etches the metal making any rust residue inert. I had managed to buy phosphoric acid at the recommended strength of 80%. It did a great job, tank is like new inside

Finally stage 4, rinse thoroughly, then dry inside of tank immediately and carefully with a heat gun.
Inspect inside with a small torch on a piece of string or wire.
I don't plan to seal the tanks as I think its too much hassle, plus I drain them if the bike is off the road.
MEGA IMPORTANT, DO THE PROCESS OUTSIDE WITH HOSEPIPE AS ACID IS NASTY
