E15 gas

Is it possible some rejetting is required?

For my 850, I add a cup of leaded 110 race fuel to a full tank.. Some lead to the valves and the motorcycle seems to like it.
Dual Amals,

Google is your friend. Car guys think so for naturally aspirated carbureted vehicles.

Not much in the way of fine tuning features with Amals, but maybe raise the needle and increase the main a step. No clue though.

There is a gas station down the street that sells 92 octane non-ethanol pump gas. I mix it and a couple of other things with premium ethanol pump gas. Works great on shorter rides. Unfortunately, out in the wild on longer rides, one is going to be stuck with refilling with straight E15. Not a huge problem with FCRs since they have an accelerator pump, but sustained WOT could get the pistons close to seizing up if no changes at all are made. Will find out eventually.

Did you try a search here? I'm thinking this has been discussed before. Could be a solution in that discussion if the thread stayed on track long enough. lol

Have not tried a search yet. I found an air leak which had prompted this thread but it's still a possibility.

FWIW,
I have run 87 to 93, leaded, un-leaded, ethanol and non-ethanol, from sea-level to 6,000ft and have not really seen any real difference in performance or function. Motor is close to 50k on the odometer, almost 20 on the rebuild due to a bad cam.
I really don't think there is much to worry about on a (reasonably) stock motor. Just my 2cents.

The more ethanol the less calories per cc in the petrol so the weaker the mixture unless you raise the needle and increase the main jet size. Methanol runners use main jets typically double the size than when run on full petrol. I had to go up 2 main jet sizes on my Honda digger engine before it would lift a full scoop of dirt again.