Here is an interesting video about Ethanol in fuel and why you really need fuel injection for ethanol fuel mixes
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I like his videos, and they are usually 99% correct. One or 2 things I'd differ on.
He quickly and superficially writes an equation for the chemical combustion and comes up with 12.5:1 (ish). That's an atom count, it's not the way stoichiometric ratio is usually represented, which is by mass. For "regular gasoline" that's around 14.7:1 air to fuel
by mass. He's not wrong as such, but his count version is not the same as the standardised mass version, just to avoid some possible confusion. (Why does this book say 14.7 when he said it was 12.5?)
Carbs needing a full rebuild every 4 weeks on ethanol blended fuel? Really? I haven't needed to do that yet. Either Harley are junk or the fuel he's using is cack (or both?).
Right at the end he describes fuel injection as being introduced so that it would allow different fuels in the future. That really isn't the reason for it. He says carburettors (...ers) "work a treat", well they don't really. They work, but not "a treat". Control of A/F with differing conditions is usually pretty non-existent, carb tuning is very much a compromise and an approximation under nearly all conditions. Transient A/F control is generally appalling, rich excursions during fast transients are huge resulting in dreadful HC/CO emissions. They usually have to be set rich to avoid lean stumbles/misfires etc. As said, they work, sort of, but not a treat.
Otherwise entertaining and educational.