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Old 03-18-2007, 09:30 AM   #11
potatoho OP
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Joined: Aug 2004
Location: Sea-level
Oddometer: 4,706
Originally Posted by bmwktmbill
Neat stuff,
It mirrors the process we all go thriugh without instruments.
Of course we guess, looking at plugs and evaluating roll on and acceleration.
Nice to put a little science in the process.
There's still the ride testing to get the best feel, but your right, the AFR lets you see what air-fuel mixture is associated with each throttle position and then you can make changes from there. As a baseline it is good to have a constant AFR, but we know that is a compromise because the motor needs more fuel at some times.

I'm a bit disappointed that a lean-ish mixture isn't doing it for me. Seems to work at the lower throttle positions without too much of an issue, but when it gets on the cam it really falls apart unless you go a bit richer.

The thing that makes me mad is if you google on the use of lambda sensors for tuning, you'll find that virtually everyone says that narrowband sensors are useless. Well, that is 100% B.S.. There is plenty of resolution on the Bosch narrowband sensor to tune between 12:1 and 14:1 (all we care about on a motorcycle). However the voltage isn't linear. You just have to build a calibrated gauge to display the non-linear voltage.

Anyways, having some type of air-fuel meter is useful for cases like mine, where I had some worn components which placed my settings far from the norm. Easy to see on the meter, so it saves time in the long run. The other benefit is that you can take virtually any weird carb and get it dialed in to a motor.
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