Old gas in tank

[Kdvan]

Hey,
I recently picked up a 99 wideglide that sat for about 2 years. I drained the old gas put in some fresh stuff and got it to start. I rebuilt the mikuni and its ready to go. My problem is from what I can see there is a thick layer of varnish coating the bottom of my tank. I dont see any  rust. I added fresh gas and a can of seafoam and cycled it through the tank about a dozen times. Seems like maybe its slowly dissolving some of the "Potty mouth" but i could be kidding myself too?

What I really want to do is get the old varnish out without screwing up the tank liner. If just running it a lot and keep adding seafoam with each fill up works I'm fine with that along with maybe an inline filter.
Otherwise I could pull the tank (remover sender and petcock) but dont know what I could pour in there to clean it,  that wont screw up the tank liner.
I see some people add acids (vinegar, phosporic, oxalic, pinesol) some people add base (sodium bicarb, oxiclean) but I'm kinda gun shy about pouring either in a steel tank....

Any suggestions ??

[Phu Cat]

Talk to a radiator shop?

PC

[koko3052]

If the varnish has solidified, why not just use gas in the tank & see if you will have any problems with it. It may just stay put & not give you any headaches. Right now it is just acting like a tank liner.

[Kdvan]

Haha sounds like a plan thanks!

[hogpipes1]

If the varnish has solidified, why not just use gas in the tank & see if you will have any problems with it. It may just stay put & not give you any headaches. Right now it is just acting like a tank liner.

All 3 of my bikes 85-03 have the   gray coating  flakes  at the screen , I just pull the P-Cock and clean  couple x yr at most. I would just let the gas  clean it up. Major blow out of all the old linner  and reseal would be  my last choice.

[Kdvan]

Thanks that's what I was hoping to hear. I figure I'll put a small inline filter right next to the petcock and just keep a spare on the bike incase.

[PoorUB]

I bought a Yamaha R1 a few years back. It had been stored for years with a full tank of fuel, but it no longer had fuel in it, it had all evaporated out. The tank was a mess! I soaked it in different  solvents and gave up and tried to pressure wash it out with a 2,000 PSI washer, it still didn't come out. I gave in and put the  bike together the way it was. It has been 3-4 years and zero issues.

[SixShooter14]

I've used Varsol and have seen folks use acetone. But probably not good if you want to retain the liner, 

[koko3052]

Thanks that's what I was hoping to hear. I figure I'll put a small inline filter right next to the petcock and just keep a spare on the bike incase.

Get one of those "old style" with the glass outer!

[Kdvan]

Thanks everyone,
Yep if it didn't have a tank liner I would bet MEK, acetone, paint thinner, methanol, ethanol or even isopropanol would all clean it out with a little effort.
I'm not in a rush so a clear inline fuel filter seems like my best bet. Ill just keep tossing in a half can of seafoam with each fill up and see where it goes.
The varnish is more like a thick sludge that seem stuck together and as long as it doesn't shake loose and clog up the filter I figure its good to go. Ill just keep a spare filter on me just in case. With any luck between fresh fuel and seafoam it might slowly eat away at the stuff.

[Dave*M]

pull the tank off the tank and get a can of combustion chamber cleaner. Spray the can in the tank and move it around. It does not hurt rubber or the liner. It will remove the varnish in the tank.

[hogpipes1]

pull the tank off the tank and get a can of combustion chamber cleaner. Spray the can in the tank and move it

around. It does not hurt rubber or the liner. It will remove the varnish in the tank.

Did you try it yourself in a lined tank.?  It did a good job when i used it on my 85 RT  that had alot of piston carbon.

[Dave*M]

yes I have done it on a few bikes with good success.It does not hurt the paint,rubber or gaskets.You would have to move it around in the tank and let it sit for an hour or so in each position.

[Kdvan]

Hey that's good to hear. I'm glad to hear you tried it and it works! Combustion chamber cleaner sounds like my go to if the varnish starts to clog the fuel filter or isn't dissolving with fresh fuel over time.
I am guessing when I pull the tank it would be a good idea to pull out the sending unit as well?

[Dave*M]

yes then plug the space with tape or a plate so that the cleaner does not leak everywhere when sloshing the fluid around

[koko3052]

yes then plug the space with tape or a plate so that the cleaner does not leak everywhere when sloshing the fluid around

I definitely wouldn't be using tape as the cleaner will dissolve the glue & then you will have a real mess.