Re: '74 CB 360 Cafe Build - Luna (renamed) and First Ride!
Mydlyfkryzis said:
Something must be wrong with my CB360. Runs great on 10% ethanol and 87 Octane. So does my 750. Weird man...
Just a lower standard of what is "great"
gasoline has 114k BTU per gallon. Straight ethanol has 76k BTU per gallon, a 90/10 mixture would have approximataly 110k BTU per gallon (114k * 0.9 + 76k * 0.1). The E10 gasoline gallon equivalent 1.036 (114k/110k = 1.036). Basically, your engine will produce 3.4 percent less power per power stroke on E10 than it would on straight gasoline because there is 3.4 percent less energy in the same quantity of fuel.
From a combustion dynamics point of view, E10 is not a homogeneous mixture. The ethanol clumps together and has a lower flame point. Thus, the ethanol burns first creating one flame front, and then the gasoline flame front begins to propagate. This is exacerbated in a small displacement engine fed by a carburetor, such as a lawn mower or a motorcycle.
Another issue is the fact that ethanol is an oxygenate, bringing oxygen with it in the fuel (-OH), when it burns it creates a lean condition vs the same settings for pure gasoline. This effects idle quality since the flame kernel initiation is at a much leaner rate than stoichiometric, such as 16.5:1 vs 14.7:1. This is true even if the gross event is 14.7:1 for the reason explained above.
So, can your CB360 be made to run "great", probably. But the described "pish-push" sound at idle is typically poor combustion dynamics. My experience is that switch from E10 to a better fuel can clean up the idle, improve power, increase fuel economy and reduce the cost of food for all.
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