Muriatic acid is a dilute form of Hydrochloric acid...it "should" take the old sealer out....

Careful with the HCl. I'd really suggest phosphoric acid for any work on rusty metal. I just wrote a thread here: https://www.vn750.com/forum/showthrea...618#post415618

Muriatic (hydrochloric) acid is stronger than phosphoric acid (usually found in toiler bowl cleaners) and does a much better job removing rust especially if it is really bad. I have done about 5 tanks with muriatic acid. I removed the petcock and plugged the opening (muriatic acid will eat aluminum in minutes). I washed out all the old oily residue and gas deposits with a product called Castrol Superclean, rinsed it good, left the cap off and let it dry, then completely filled the tanks with muriatic acid, let soak 24 hours, and dumped it out. ALL the rust was gone. No putting nuts or rocks inside or shaking or anything like that, just a 24 hour soak in full strength muriatic acid. One tank did develop a couple of pinhole leaks, as it was already rusted through and the rust was plugging up the holes. I coated the inside of that one with POR-15, and used it for a couple of years. IMO, if the tank doesn't leak, DON'T coat it with anything. And don't use Kreem even if it does leak. On the Vulcan 750, the fuel gauge sending unit would also have to be removed, and the hole in the bottom sealed somehow. Muriatic acid only reacts with metal, it will not harm plastic or glass. Wear latex gloves, eye protection, and avoid breathing it the best you can. It must be used with care, but it WILL remove all the rust. It will not remove tank sealer, as it is not metal. Adhesive remover will get some of it out, as will acetone, MEK, and a few other chemicals, but I know of no way to get it all out. Motorcycle restorers hate the stuff. They usually cut the bottom out of the tank, remove it manually, then weld the tank back together, a VERY expensive job. To me a lined tank is a ruined tank.

I did the Muriatic acid in my tank over a year ago and it still is rust free. It worked very well!
I had the baking soda ready and followed the instructions to T.
It was soooo pretty afterwards!

Having done it several times, I am convinced it is the way to go. It does work, and works great. But, it is something you have to be careful with. I would not recommend it to anyone who has never used it before, especially without making it clear to them that it can be very harmful if you do not take the proper precautions. I did see they have a newer, supposedly safer version of it at Walmart, with less fumes. Don't know if it would work as well or not.

it took me 20 minutes to find this thread can someone please sticky this

i will be trying the safer muratic acid on my spare tank mainly because it is cheaper

I just stickied it for you

awsome brother

An alternative perhaps worth a mention. I have used this method a few times over the years. The last time however I altered it slightly and found it a bit easier.
Although the small (1/4") nuts, or small steel pellets work great, I found (by counting how many I put in) that retrieving them back out of the tank (even with a magnet) can be a pain, and quite time consuming.
The last time I preformed this procedure on a rusty tank, instead of small nuts, I dropped a 3' length of "S" hook chain (the chain made of approx. 1" S-hooks crimped closed in the center) into the tank.
This delivered the exact same results, with the exception of retrieval was much, much easier and quicker.
Also, in addition to the procedure, because I live in Florida (high humidity) and I was also performing an out of frame major on that bike, I knew it would awhile before putting the tank back into service. Once I was sure the tank was completely dry inside I poured about a pint of very light weight oil (I used a bulk air tool oil) into the tank and turned the tank in every conceivable angle to assure getting it to roll over every bit of interior surface. Draining it then setting the tank so that the excess would make it's way out of the petcock opening. This protected the bare metal surface from re-rusting and the fine residue it left was quickly dissolved by the first fill of gasoline.
Just thought I'd chime in on that note. Hope it's of use.

Regards,

Also, lots of tiny nuts threaded on a long string will work. Drop the nuts in and secure the string somewhere. Untie when done and remove string of nuts