Consumer Electronic Infos

bikinkawboy asked:


No dumb answers please. Here’s the deal, my bike has an electronic sending unit on the front wheel that provided 23 pulses per mile. Those pulses provide signals for the mechanical odometer display, the trip computer and the digital speedometer. Here’s the problem, the odometer is very accurate, the mileage and mph the trip computer displays is very accurate but the speedometer reads 10% fast. The speedometer isn’t defective, all of this model came from the factory this way. Is there any way to correct the displayed speed without affecting the accuracy of the other units? What principle is used to count the pulses and convert them into a readout?
The bike (motorcycle) is an ‘84 Kawasaki Voyager. I know the odometer is accurate to within 1% by comparing to known distances (mile markers on interstate). I know the true ground speed by timing the time required to cover a known distance (60 mph=1 mile in 1 minute). The trip computer provides an active display of the distance covered since the last start up or reset of the distance, the average speed since the last startup or reset as well as a number of other functions including stopwatch, mpg, fuel left in the tank, ect. All 10 computer functions use the inputs of distance, time and current fuel consumption. The speedometer display is seperate from the computer display.
First of all, sorry about the word tachometer, I meant speedometer. But I’m assuming they both work on the same principle of counting electrical pulses whether it’s from the signal generator on the wheel or pulses from the ignition coil.

I appreciate all the wise information from you folks. Since the speed display is in LCD numerals, I have no needle or spring I can calibrate like I’ve done on mechanical meters.

The 23 pulses is per wheel revolution which comes out to around 17,421 pulses per mile. Since the trip computer (a seperate unit) uses that number of pulses to correctly calculate speed and distance, it must be the time part of the dash’s speedometer that’s incorrect. Incidently, 20 years ago motorcycle speedos were universially incorrect, always reading fast. A good way to slow the rider down I guess and make the bike seem faster than it really was.

Lydia