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TECHNICAL => HELP! => Topic started by: southwos on April 18, 2021, 12:26:44 AM

Title: Does speedometer affect fuel ratio settings?
Post by: southwos on April 18, 2021, 12:26:44 AM

Just bought a 2007 with 6500 miles.  On a run I hit an indicated 180 on the speedometer.  That App on my phone (Waze) was showing 160ish.  The bike has a Yoshimura pipe and a powercommander III, I'm wondering if because the speedometer is so far off it's it would be running lean or it the bikes computer monitors the speed/RPMs in another way.  The bike was still pulling hard and was not having any weird sputtering and didn't smell of running rich?  This is my first Busa and I have been riding for 40 years.  Not new to bikes, but want to know about particulars of a Gen 1 Busa.

Title: Re: Does speedometer affect fuel ratio settings?
Post by: RansomT on April 18, 2021, 10:35:56 AM

That speedo error is about right.  Speed on the gauge is based on a sensor reading front chain sprocket, the ECU doesn't care. You take the speedometer reading with a grain of salt, especially if the front sprocket is smaller than stock.
All of the calculations on fueling comes from the RPM (IIRC, crank position sensor), Throttle Position Sensor, Gear Position Sensor and a goup of temperature/pressure sensors.