I left E10 in the tank too long

[Rasputin]

I don't see the point of fighting so hard to find e-free gas. The status are rapidly dwindling and if you go on any trip you most likely won't find it. Dial your bike in on the gas readily available in your area that you will usually use and take care/precautions.

+1 on what Nate said. Set it up to use fuel readily available anywhere and problem solved.
Up here all of our gas has 10% ethanol and there is no getting around it. There are special fuel stabilizers for ethanol flavoured fuel and many of the old stand-by's will not work. I used Seafoam one winter....first and last time I try that! In over 40 yrs of riding I have never seen fuel that gooey and useless.
The stuff up here that is NOT used for ethanol fuel is marked down so cheap everyone buys it without knowing. A gallon for 10 bucks type thing...what does that tell you? Stuff that was designed 10, 20 , 30, yrs or more ago simply does not have the chemical suitablity for our more modern fuels.
Seafoam and all those work well to clean stuff up (sorta) but as a fuel stabilizer it sucks wind, as do many other oldie goldies from the past.

[Dragon Tamer]

I think that Nate may be right here, tune the bike for what you can get for fuel and run with it. That is the way I have done it for a long time and I don't seem to have near the trouble that other people have reported. I also believe that daily riders have less problems thanweekendor monthly riders do. At least start it up and warm it up a couple of times a week.

The use of SeaFoam is still out with the jury. I have used it since I discovered it and have had nothing but good luck with it. I use it in everything that will sit over the long hard winter up here. Start with the last few tanks of gas that you think you will get to use in the fall. I use a precisely measured amount in each fill (somewhere around three "glugs" out of the bottle). This is figured using the formula X+M=B, where X is the amount recomended by the manufacterer, M=more, and B= better. Simply stated, if a certain amount works well, a bunch more should work better. The results, at least for me, have been very satisfying. In the case of my bikes I add the usual amount on the last fillup and drive the bike home, this will use a small amount of gas out of the tank and leave enough room to allow for some expansion if the weather warms up. Every spring so far the bikes start up the first time just like I had run them yesterday.

However, having said that, my friend Poppa Smurf tried it last fall and NOTHING that he put it in would start this spring! I was not there when he installed it and perhaps he did not use my highly scientific formula. Whatever you use it should be used for at least a few tanks of gas before storing, if you just dump it in it will not be in the carbs etc as needed and most likely won't work as well for you as it would if it had been run through the system. The inside of the gas tank on the Dragon looks show room fresh yet and this is on a bike that is pushing 200 thousand miles.

YMMV!!!!!!!!!!!

[Bonz]

From the description, sounds like the black stuff was in the filler opening, but not anywhere else, since you were able to wipe it off with your finger. Correct me if I'm wrong.

E10 has been the only fuel my 80 SG has ever seen in Colorado for it's entire life darn near, and the previous owner had it sitting literally for years with much less than a full tank, and you could eat off the inside surface of the tank. He used Stabil and the gas I rode it home with 4 years ago was at least a year old. BUT Colorado is a dry/non-humid climate.

I did some reading up on ethanol/tank mold and seem to be finding it is a mildew that you probably had. Ethanol is a food source for mildew, so that sounds like what you have going on, as much as I have never heard of it before. The Ethanol didn't cause the issue, per se, it just fed the mildew that probably started from being in a moist climate (Georgia?), proabably got really hot where the bike was stored and the tank vent didn't vent, keeping a nice hot environment for the mildew to form and feed off the ethanol.

[Poprock]

I hate E-10 sitting in my tank too. I like to run 2-3 tanks through it in a day when ever possible. When it has to sit, it has Sea Foam in it. No grass grows in there.

[jetmechmarty]

Howard, you're probably right. The bike is an XS650 that I've had for 30 years. I can reach the bottom of the tank with my finger and wipe the black stuff off. I have been keeping the tank full, but the bike went on the back burner last year. I haven't run a full tank through it in that time.

I just came home last night. I'll drain the tank and let it dry. Perhaps that will tell a story. I now have five gallons of pure gasoline ready for top-offs. Over the winter, I will keep the operating bikes full with that.

[Bonz]

Sounds like you have a good start and hopefully successful finish to ridding the tank of the mildew.

Keep us posted how you get the stuff out of there once the tank is dry. Drying the tank should kill the mildew, then it's just a matter of getting it out of the tank.

[jetmechmarty]

I let the tank dry for two weeks. I sprayed the inside with fogging oil. It's going to be fine. With E10, I think it might be better that way than with the tank full.