I recently noticed rust flakes on my petcock screen and in the bottom of the carb float bowl on my 2000 Dyna Wideglide. Tried flushing the tank by adding Seafoam to several tanks of 93 octane gas, but the flakes just keep on coming, so I bought a flexible shaft inspection camera from Home Depot that allows me to see deep up into the tank. It really works great for the filler side of the tank, but the diameter of the head of the camera is a little too large to fit into the petcock opening, so I can't see into that side.

Sure enough, the bottom of 1/3 of the tank had moderate rust where the HD-applied liner coating has been eaten away and is flaking elsewhere. My theory is that the ethanol-blend gas attracted water moisture over time and then the water settled to the bottom of the tank (water is heavier than gas) and the water/ethanol proceeded to eat away the tank liner over time, completely eating it away at the very bottom of the tank (allowing the bottom to rust) and leaving the lining flaking at the liquid line.

What a great tank lining product HD came up with. Won’t withstand the ethanol-based gas, but is tough enough to resist stripping with anything short of nuclear waste. Through mining the internet, I discovered that HD stopped coating the inside of the tanks around 2004, probably because they found that it could not withstand the ethanol-blend gas mandated by the gov about that time. It would have been good if HD had issued pre-2004 owners a warning about the problem and steps for prevention, but did not that I know of.

Here are the steps that I have taken so far:

First tried rolling BB's around in the tank to remove the semi-loose rust/liner flakes, then filled the tank completely with apple cider vinegar and let it sit for a couple days. This was really the trick to remove the surface rust but did not do much to phase the HD-applied liner.

Trying to strip the old HD liner coating out has proven to be a monumental PITA. Tried dissolving some of the liner flakes that came out of the tank with Acetone and also lacquer thinner and they didn’t even phase it. Had to go to a wicked paint stripper called POR-STRIP (~$20/quart), a very toxic liquid stripper that is mostly Methylene chloride and, of course, will eat the beautiful paint off of the outside of the tank if it touches it anywhere.
I wear thick rubber gloves and a 3M gas-odor respirator and googles when pouring the POR-Strip or when working with the tank with it inside. This is really nasty stuff, so be absolutely sure to take every precaution to protect your skin and lungs when exposed to it if you are unlucky enough to find yourself having to rectify this problem with your bike.

To protect the paint on the outside of the tank, I first waxed the outside of the tank very thoroughly and wrapped it with a layer of Saran wrap and then a layer of aluminum foil, then reinforced it with duct tape around the filler inlet and petcock openings. Bought rubber plugs from ACE to seal the inlet, petcock, crossover and vent openings and used my old stock filler cap and fuel gauge cap to seal those two openings for extra protection. So far this has worked well to protect the paint.

Carefully poured the POR-Strip through the small filler hole using a funnel, being very careful not to let any splash on the outer tank, even though it is covered for paint protection. Have had one quart of the POR-Strip liquid in the tank for about a week, rotating the tank several times a day and positioning the tank at different angles to puddle the stripper at different places along the tank walls. It has removed all of the HD liner (where I can see with the inspection camera) where the stripper could sit in direct contact with an area for several hours, but I can still see bubbled-up, half-melted patches on the sides of the hump in the middle of the tank halves where it is impossible to puddle the stripper on the surface. Just can't figure a way to get the stripper to get sufficient contact time with this area long enough to completely remove the liner coating. Because of the “two-halves” tank design and only having one small (~1 inch or less) diameter hole on each half of the tank to work through, I am not able to scrape the remaining liner from the tank “hump” walls.

Short of buying 5 gallons of the stripper to completely fill the tank (would cost about $400 to buy that much of this stripper), I am now at a temporary loss as to what to do to get the last remaining old liner out of the inside of the tank.

Draining the stripper and flushing the tank with water to remove the residual may be enough to break some of the remaining patches loose, but I doubt it will completely remove the remaining liner along the sides of the “hump” between the two tank halves. If I don’t get the old liner completely removed, then the Caswell tank lining product I have chosen to use to recoat it with will flake where the residual HD lining is clinging to the surface. What to do? Any suggestions? Is there a media blaster that has 18” or longer flexible wands small enough to go through the ~1” inlet and petcock holes?

 

Sounds like there will be an aftermarket tank in your near future.

 

Nope. I like the factory paint scheme too much.

 

Dunno about the new tanks but on the older bikes I pick about 10 foot of this chain drop it in and started shaking the tanks , doesn't deform anything but will knock loose old peeling liner and rust patches and you just fish it out with a coat hanger and use an air hose & wand to blow out the insides real well.

http://hardware-group.com/display.asp?id=94

 

Excellent! Just bought 10 ft of this at the local Ace Hardware and will give it a go tonight.

Thanks TwiZted. Much appreciated.

 

Back in the day, I used Kreem to seal up a rusty Honda tank.
http://kreem.com/fueltankliner.html

 

Keep in mind it won't take off any coating that's got a good grip on the base metal , what it will do is knock loose any bubbled or edges already coming up. Aside from acid baths it's the only way to deal with rust crud in old tanks. Few variations like BB's or bird shot and sand but those can be a bear to clean out.

PS pull the petcock out completely first.

 

The gas today makes that stuff unusable.

 

Same problem with my 2000 Fat Boy tank a few years back. Found the residue in my carb on rebuild that got me started looking. Pulled the petcock and found a lot of the liner flaked and built up on the screen,d and found the same corrosion on the bottom of the tank.

I know the previous owner let the bike sit and it sat exposed on a porch or carport. Didn't help the situation. Anyways, a friend that is also an Indy tried a couple of things, cleaners for the rust and tricks to break loose the flakes and returned it to me. He recommended I check the filter screen for flakes over time and hopefully most of the flaking would stop and to not leave the tank sitting any amount of time with a low level of fuel. I also put in an in-line fuel filter (Yes-it's carbed) for small rust particles.

Over time and checking the flaking progressively got better. Last time I checked, there were no flakes on the tank screen, but I still am running the in-line filter. I too didn't want to swap tanks due to my bikes paint job.

 

POR 15 makes a nice kit that will take care of your problem, just follow the directions. I've had very good results with it.