As I've posted before my speedo is over reading by 20%..reads 60mph at 50mph actual. The sprockets are standard gearing, so it's the electronics thats throwing the incorrect speed. I know I can buy a speedo-healer to sort the error, but I was wondering whether anyone knows how or where the speedo picks up it readings. Is it a sensor on the gearbox output shaft or does the ECU make a best guess based on throttle position, engine speed and gear selected. The reason I ask is that the speed reading seems to vary depending on gear selected, even though the road speed and revs stay constant. Not by just a couple of MPH either...but somewhere between 5-12...it's getting annoying as going through areas where there are good chances of the traffic boys doing speed checks can be just a gamble..
Get a gps and sit at 60mph indicated on the clocks, see what the gps says then do the same in different gears i.e. hold the speed at 60mph regardless of gear selected & see what the gps says. Give me a call if you want a Speedo Healer & I'll sort a discount for you.
Thats how I worked out how far over the speedo was reading though I didn't try different gears, I'll have to find a nice long stretch of quiet road...or a runway I think a speedo healer might be on the cards though as the over read is also putting extra miles on the clock...
I have a CBR1000RR8 and checked it's speedometer earlier this year. With a 50% worn rear tyre and standard gearing, the speedometer over-read by 8% e.g. speedometer said 108mph at same time that the GPS said 100mph. It seemed to be about 8% over, irrespective of gear or speed. Obviously, the speedometer would be slightly more accurate with a new tyre. From what I remember, the type approval rules (for cars, but I assume that rules for bikes are same) say that speedometers can over-read by up to 10%, but must not under-read at all, so 8% over is legally acceptable - but 20% over wouldn't be...
