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Black Robotics “YellowBox”
Electronic Speedometer Calibrator
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Suzuki has a long history of building technologically advanced, reliable motorcycles, and has been responsible for many innovations over the years. Being
the 21st century, with advanced computer technologies, sophisticated manufacturing processes that are capable of such mind-boggling precision, you would think an accurate speedometer would be a walk in the park
Well, somebody forgot to tell Suzuki about all that cool stuff in the “speedometer developement department.”
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The new 2001 Bandit 1200’s use the same step-motor speedometer system that is common on many of its other models. The system itself is capable of great accuracy, yet Suzuki always
calibrates it 8% to 12% high. Like most Bandit riders, I actually like to know how fast I’m really traveling. Its always useful when challenging a law enforcement officer who’s about to write you ticket.
A speedometer that indicates 90mph when you are in fact moving at 83mph is, at best, horribly inaccurate. - Enter the YellowBox from Black Robotics.
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The Suzuki step-motor system reads off of a magnetic sensor located on the case housing that covers the front sprocket, The sprocket itself has a magnet on it that passes the
sensor and sends a signal back to the speedometer. Each pass results in a ‘pulse’ being generated, the more pulses per second, the faster the speedometer reads. The YellowBox takes the pulse
signal, and corrects the number of pulses sent back to the speedometer based on a percentage off-set. The result, is an accurate speedometer. The Yellow box can be calibrated down to a .25 percent,
allowing for extremely high accuracy.
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Left: The sensor location on the 2001 Bandit 1200.
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The first step before installing the YellowBox, is to determine how far off the speedometer is. My preferred method was using a Global Positioning Sensor (GPS), as they are
exceptionally accurate when used properly. First thing I did, was find a very flat stretch of road, fairly devoid of traffic. It is important not to use a road that has notable changes in elevation, as
it will affect the GPS speed reading. I ‘mounted’ the GPS in my tank-bags clear-top so I could glance at it while riding. (Note/Disclaimer: This IS dangerous, you have been warned. Dont
blame this author/article/site if should kill/hurt yourself and/or wad/damage your bike). On my first run, I set my Bandit exactly at 60mph, and allowed the GPS a few seconds to adjust. The GPS indicated exactly 55.3mph. For verification purposes, I did a another run, this time setting the speedometer at 90mph, the GPS reading was 83.0mph. I went ahead and duplicated both runs again to make sure I had completely accurate readings (its an Engineer thing).
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The above picture shows the v3 YellowBox is very compact..
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The Math - Its important to calculate the percentage off-set using the formula that Black Robotics uses. In this case:
<Indicated Speed> divided by <Real Speed (GPS)> = % off-set round to closest .25%
60 / 55.3 = 1.0849 : Rounded to 1.085 (= 8.5%)
90 / 83 = 1.0843 : Rounded to 1.085 (= 8.5%)
As you
can see, taking readings at two different speeds provided good verfication of accuracy. While calculating to the 1000th’s isnt totally necessary, it does tell you how close/off you are. Once you’ve
calculated/verified the percentage off-set, the YellowBox documentation comes with a very handy chart to tell you exactly how to set the dip-switches.
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The wiring is very straight forward, and the documentation comes with excellent instructions. Suzuki uses a 3-wire system, wiring up the YellowBox involves cutting 1 wire, and
splicing into the other two. Unfortunately, the wiring diagram is unavailble online at the time of this article.
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Above: The YellowBox with re-wired sensor harness.
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The YellowBox secured to the main wiring harness, and ready to go.
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After re-installing the sensor harness with its extra connector, I simply zip-tied the YellowBox to the main wiring harness. On my Bandit I am running a Stage-2 kit with K&N
pod filters, so there was plenty of room. On Bandits with the airbox intact, the YellowBox can be mounted further back, under the gas tank mounting bracket, where it will clear the airbox. The total
install time took less than 1 hour.
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After re-assembling my Bandit, it was time for a test ride. With GPS in bag again, I set back out on my road of choice, and proceeded to an indicated 60mph. A quick glance down at the GPS
revealed a steady 60mph. With a minor twist of the wrist, an indicated 90mph, with GPS confirmation. I proceeded to check some higher speed readings, and the accuracy was perfect into the triple-digits.
The YellowBox is state-of-the-art, sturdy, and compact. The documentation is easy to understand with plenty of diagrams, and help is readily available on the
Black Robotics site. Overall, an outstanding product that is easy to use, and does exactly what its supposed to. If you are tired of not knowing how fast you are really going, then the YellowBox is the solution.
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Griff, Maximum-Suzuki.com
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Any speeds mentioned in this article which are above the legal speed limit, are complete fabrications, and the author is obviously lying.
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