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Discussion Starter #1
Hi Folks!
I am in the process of reviving a '87 K100RS and the next bit to tackle is the fuel tank. This bike has been sitting for 7 years and the tank was really bad. I have cleaned the tank as best as I could with Oxi clean and removed the faulty fuel pump, the deteriorated vibration damper cushion and all the rotted fuel lines. I have three questions:

Should I remove the fuel level indicator prior to deep cleaning with lacquer remover and muriatic acid? Will wither damage the electrics?

How can I test the electrics without adding fuel, installing the new fuel pump kit and reinstalling on the bike?

How long will the fuel pump electrics function on these bikes? Should I replace them seeing as I have the tank apart?

Thank you in advance!


3 Posts
I don't know about the electronics but here's how I would remove the rust:
I researched this for weeks and here’s how I removed the rust in my tank:
If real bad, add a cup of nuts and bolts and shake vigorously till the big chunks are gone, empty out.
Vacuum tank
Power wash
Put 50/50 mix of phosphoric acid (under $10 / gal. at tractor supply) & water in tank, swish around, rotate occasionally and let work for at least 8 hrs.
Always Add ACID TO WATER-NEVER Add Water to Acid
Empty tank
Rinse with water
Next fill it with a solution of water and a small amount of baking soda to neutralize the acid. After 15 minutes, rinse the tank with water again
Fill the tank immediately with a Water/Baking Soda solution. ½ box of baking soda in full tank of water
Immediately rinse with 1 qt gas with some heat or WD-40(1 oz. per gal)
Next rinse with pre mix- gas 25:1 2 cycle oil, swish around.
Used acid can be diluted and sprayed into garden.
Good Luck,
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