MOPED ARMY

If it's running premix , just close the petcock and top off the tank , tighten the cap in place .

If straight gas , add oil and do the same as with premix .

If you want to get rid of some rust :

( I should just boiler plate this )

I rec'd my order of wood bleach ( Oxalic Acid ) and thought it best to test it before I subjected my fuel tank for rust removal .

I mixed a rather mild solution for the test . Here are some before and after pics :

Before :

After :

The parts looked almost this good after just a couple of hours bath , but I left them in over night to see if the deep reaches would be 'taken care of ' . The pulley was totally rusted .

I pulled the parts and rinsed them in a bath of hot water , then let them dry . The Oxalic acid seems to eat rust and leave a protective coating . I wiped some of that coating off the rear brake plate . Also note that the acid does not effect painted parts ( a big plus ) .

This was an experiment for me . My Simplex had a bit of rust forming in the gas tank . Not too bad considering the bike is 55 years old . I'd read that different acids worked for removing rust .

I used muriatic acid to clean my XT350 tank with decent results . That tank did flash rust and I retreated it and then neutralized the acid ASAP . It still formed a small amount of flash rust . I'm running it with an in line paper fuel filter and haven't had any problems .

The Simplex tank is a bit more rare and harder to find . I was reluctant to use muriatic acid in it for those reasons . Through research , I read about oxalic acid , sold as wood bleach . Oxalic acid is a lot safer to work with , but still requires due caution ( READ THE LABEL ) . It's not nearly as toxic as muriatic acid . It does NOT harm painted surfaces . It just eats rust and leaves a protective coating on the steel after being thoroughly rinsed with water .

I used a diluted mixture from what is suggested , which is 12 ounces to 1 gallon of water . I used 12 ounces to 2 gallons of water . Being as the solution was weaker , I left the mixture in the tank twice as long and the results are shown below .

This is what I used :

Here's the rusted tank :

And, here's the tank after being filled with oxalic acid for a couple of days :

This stuff really does work great .

I've been using it for about 3 years now. It's very effective.

That's some pretty caustic stuff . Definitely be careful .

Not sure if baking soda neutralizes the acid or if something else is needed .

And , have some heavily oiled premix ready to hopefully hold the flash rust to a minimum . (edited)

The smokey looking coating left after rinsing the oxalic acid did not present any problems in either bike tank I did

I just poured premix in the Simplex tank and gasoline into the XT tank , once all water had been dried out .

And , no problems on the outside of loose parts .

I did wipe clean any surfaces of parts that required paint and any unpainted surfaces got a shot of oil or anti-seize ( bolt/screw threads and such ) .

I did the vinegar followed by baking soda method I found on here. Worked wonders on my tank.

Cleaning my tank out did clog my petcock though

PD, thanks for the help, I started the oxalic acid clean out today!

Good you got it going . ;)

I was too lazy to read the whole article the first time. 12oz per gallon! Sorry