Triumphrat

Sheepdog

10% ethanol fuel requires 3% richer tuning to match the performance of pure unleaded; 15% ethanol requires nearly 4.5% enrichening. This is why Bonnevilles seem excessively lean as stock in the USA and why gas mileage is not as good as one might expect. The negatives of ethanol fuels don't stop there, either: Because ethanol is hygroscopic water can be absorbed into your fuel, pooling at the bottom of your fuel tank. This can account for hard-starting, fuel tank rusting, and the formation of aluminum oxides in your intake system (especially carburator float bowls). If pure unleaded is not available, you can reduce the negative effects of ethanol fuels by stabilizing your fuel (I use Seafoam) and closing your fuel tap (if your bike has one) at the conclusion of every ride. These precautions are even more important if your bike will not be used for two weeks or longer.

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2003 Bonneville T100 and 2007 Moto Guzzi California Vintage

RickMcCl

The two main problems with ethanol that I'm aware of are that it draws moisture (water), settles out rather quickly, hardens many rubber and plastic compounds, and is corrosive (OK, four).

Rick

49erx2

As pointed out, it's a good idea to put higher octane fuel in the bike during winter when there may be longer periods of the bike being parked between rides. Helps keep the octane above minimum requirements as the octane does degrade over time.

If a bike will be in even longer periods of storage it is good to fill the tank as full as possible (helps prvent rust inside the tank) and to also add a fuel saver which will keep the octane from dropping much for up to about a year. These products are available at Walmart and the local auto parts store.

And if someone wants to really go all out they can add an octane booster to further ensure that the fuel is at full octane when the bike is eventually restarted.

Doing all this is another option to actually draining the entire fuel system as much as possible prior to even longer periods of storage.

ruger

Matt Capri of South Bay Triumph recommended the mid-grade gasoline.
(Off topic FWIW: He also recommends a semi-synthetic oil as the full synth didn't work as well with our clutches.)

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• Ruger •
Long may you run-Neil Young
ARK/Dominators/Works/Progressive/EBC rotor/Rocket III master cyl/Pazzos/170 rear/TPUSA tach kit/520 kit,19T/Denalis/Bashplate/DEcosse MOSFET upgrade/More crud/Ruger's Garage

Olhogrider

Time causes octane loss? That's a new one. AvGas (for airplanes) has stabilizer because planes can sit for months without flying. They also do not use alcohol as it will suck water out of the air. Filling the tank does not allow as much air in the tank resulting in less condensation.

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Damned Dirty Biker!

49erx2

You're right the octane loss is not entirely the issue with older fuel. It's the general degradtion including octane loss over time. Aviation gas is formulated a bit differently from motorcycle fuel. Still a good idea to use a stabilizer for longer periods of bike down time.
Here's a good link which includes a couple of fellows in the fuel industry and their comments on the subject.

http://forums.pelicanparts.com/porsc...se-octane.html

RickMcCl

I use a marine stabilizer pretty much every time I gas up.

I figure the benefits it provides makes it worth it; even though I'm running ethanol free gas.

One ounce treats 16 gallons of gas, so one bottle lasts a long time.

Rick