Ethanol!

MexicoMike · Apr 16, 2018

If it's a concern you could always drain the tank and then pour that into your closest car's tank. I bought a new in '08 FG fastback tank from Burton's Bike bits. They said it was made with ethanol-resistant resin but I Caswell-coated it before filling it the first time anyway. No signs of any problems yet.

I have always used 87 octane in my Commando with no sign of detonation using factory-spec timing setting. As noted, performance-wise , higher octane fuel than the engine needs won't do anything but lighten your pocketbook.

Craig · Apr 16, 2018

I went down to local bike shop last week and got a 5 gal. can of 114 octane racing gas ... the boys say pure gasoline none of the corn stuff, put a half gallon in with some pump high test trying to get around 100 test ... starts and runs fine but weather still not cooperating, looks like next week will be good FG tank seems fine so far .... also nice decal on can say contains lead , who knew

Danno · Apr 16, 2018

bill said:
why in the world would want to throw away money on any thing higher than 91 octane fuel. you must have a 14-1 compression norton. same goes for the lead additive and octane booster. norton valve seats are hard enough that the no lead is NOT an issue and the compression is low enough on all but a combat that pump gas is just fine . even on my combat with .020 off the pistons i have NO issues with 91 octane. one more thing to high of an octane will actually slow one down

Oh I don't know, I guess the same reason I like to throw money away on leaky old British twins when I have a fast, comfortable, perfectly reliable motorcycle that takes me all over the country and I have less stuck in it than either of my two Nortons. I must be outta my mind.

RoadScholar · Apr 16, 2018

Fast Eddie said:
Well yes, that’s an option. But a tank full of petrol is not always an easy thing to dispose of!

A very good point. I had 5 gallons of drunken 89 that I kept too long for my generator, but I live about 1.5 miles from one of two Massachusetts fire fighting academy's. So, I called them, they burn stuff up al the time, I figured that gasoline would be something that they practiced with. They didn't want it! Go figure.

It took almost two years for it to evaporate.

MikeM · Apr 17, 2018

Atlas Commando said:
One weak point on my 'finally started the rebuild' '72 Combat is the fiberglass roadster tank. The tank looks like it was coated before I bought it back in 1985. It appears we finally have a source of re-pop steel tanks, but I have been planning to simply use the fiberglass tank. I saw the bike running around for a couple of years before I bought it, and absent-mindedly thought that 'the coating must be working'.... but I think back then it was pretty easy to avoid ethanol, so I really can't say that I've got a well coated tank for sure. I've been thinking of adding a drain valve to the fuel lines and suffer the hassle of draining the tank in between rides. I believe some fuel brands don't have ethanol in their high-test, but chances are I will get a hose full of 87 with ethanol before getting to the good stuff, not ideal with a roadster tank.
QUESTION: Is anybody avoiding ethanol attack by draining their tank routinely? If the tank mostly sees 'fresh' ethanol mix can I get away with it?
I can't believe I passed on a steel roadster tank at Walridge's for $90 back in the late 80's.........

I drained the tank for the first 3 years I had it running. Everytime I got home, I drained the tank. Got tired of doing that and finally picked up a steel repop tank. Its not perfect but I no longer have to drain.

Atlas Commando · Apr 17, 2018

Thanks for the info MikeM. It sounds like draining will protect the tank, long enough to find a steel tank if I decide to keep the bike longer term. Present plan is to ride it a few hundred miles and then find a worthy owner who can enjoy making further improvements.

elefantrider · Apr 18, 2018

What about Sta-Bil storage additive? Does that work to prevent deterioration of the fiberglass tank?

ewgoforth · Apr 18, 2018

I've been running a '72 fiberglass interstate tank on my 1973 850. Try https://www.pure-gas.org/ for stations that have alcohol free gas, they have the octane rating on msny stations too.They also have cellphone apps. I almost never put alcohol in my tank.

On long trips I ride until I'm low on gas then find my nearest alcohol free pump. Easier to do with an interstate tank though. Also since I have an 850, 89 octane is all I need. I've seen a few alcohol free pumps that dispense 87, but most are 89 or more.

Danno · Apr 18, 2018

elefantrider said:
What about Sta-Bil storage additive? Does that work to prevent deterioration of the fiberglass tank?

I don't think so. The new blue stuff is supposed to mitigate ethanol separation, but the only thing that protects old fiberglass tanks is to not pour any ethanol in them.

Be happy you don't have a plastic-tanked Ducati. Ethanol makes them swell up so bad the mounting holes don't match. Alloy replacements are around $2500.