Air/Fuel Ratio
#11
An engine cant be constantly ran at stoich. There has to be fuel introduced into the exhaust to light off the cat. Most engine OEM's use a strategy called perturbation. This runs a cycle or two lean, and then a couple rich (around 13.5/1). Dont ask me how I know this. I might have to kill you if I tell you.
#12
Yes, you're all wet. As mkguitar explained, there is no one "ideal" AFR. One of the advantages of EFI is it allows a far greater degree of matching AFR to the required conditions. You need lower AFR (more fuel) running up a hill than you do running down a hill. You need lower AFR accelerating from a dead stop and getting up to interstate cruising speed than you do running at a steady speed on a flat highway.
13:1 is extremely rich for virtually any riding condition; and, if you run that regularly you'll probably have a lot of unburned fuel contaminating the oil impairing the oil's lubrication capability.
Another advantage of EFI is the injectior allows the fuel to mist/atomize faster with the intake air compared to carbs which drips fuel into the intake air. So, for a given rpm and load, EFI allows less fuel to be added than a carb due to EFI's more efficient mixing of fuel with a given volume of intake air.
Carl
13:1 is extremely rich for virtually any riding condition; and, if you run that regularly you'll probably have a lot of unburned fuel contaminating the oil impairing the oil's lubrication capability.
Another advantage of EFI is the injectior allows the fuel to mist/atomize faster with the intake air compared to carbs which drips fuel into the intake air. So, for a given rpm and load, EFI allows less fuel to be added than a carb due to EFI's more efficient mixing of fuel with a given volume of intake air.
Carl
#13
Naw, its lower than that as you roll on (accelerator pump). Once you are at WOT then 13:1 is about where you want to be, but as I said before it isnt that important, 12:1 to 14:1 gives about the same torque and power.
Last edited by kingkingking; 06-17-2011 at 07:22 AM.
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