Checked against my GPS, mine is pretty typical of vehicles. My speedometer is about 3 mph faster than the GPS indicates. Varies a little between 2-4 mph fast, but usually 3. I tested anywhere from 20-65 mph with the same results.
The speedo adjustment procedure shown over at http://www.ibmwr.org/ktech/speedo-cal3.shtml is for the old analogue dash assemblies of the 70's and 80's On modern dash assemblies the adjustment is a setting in the Dash/ABS if it is able to be done at all, on the 650GS BM there is no ability other than changing the sensor ring. On the G650X there is an ability to change it and the procedure is published at Advrider. For the Terra it is an interesting question I notice reports above indicating accurate results with both 17" and 18" wheels so something is adjusting speedo calibration. Other than a setting in the diagnostics system another possibility is a solder link on the Dash circuit board. They use that for changing Miles/Kms on ODO with the 650GS
done, chucked on two 44 slot Sensor rings and went for quick spin, my 8% error is gone and basically the speedo is exactly the same as my gps now, sweet, it pulling 4350 RPM at 100k which is what is was doing before at 108k. All thats left to do is sort some countersunk screws on the rear and get them both electro galv'd and ride.
yes that was the easiest way of dealing with the offset which is 3.2mm, so they lasered me 6 x 1.6mm thick washers. All up cost about US$45 (still have to galv them yet), so if anyone wants a set, I can get get a set made with any number of slots. Just do the math, mine was over reading by 8%, so remove four slots (4/48= 0.0833r or 8.3%). easy!
Not sure if this is applicable to BMW bikes but their cars intentionally have an +8% speedo variation with the odometer & tripmeter being correct. I found this when driving with my Garmin satnav + looking at the vehicle speed reading on my ODBII reader with the dealer confirming this. It may pay to check the odometer over a measured distance or satnav to see if your modified sensor ring has affected this.
your probably right, which means my economy and range will suffer, but at least I can take the speedo at face value and not have to reach for a calculator to see how fast I'm going.....our cops are real tough on speeding here....and now I don't have any excuses if I get caught where before I could blame the Germans!
Where do I get one? I was thinking to build a signal conditioner that would change e frequency of the signal accordingly. I like this solution better!
Wow very nice work, looks better than OEM! I have 17" wheels front and rear so my speedometer is off as well. Fortunately the error is on the slow side so I wont get into any trouble!
Kiwiape.... I also posted on your profile wall... I know this is an old post but I would really like to buy one of the custom tone rings if you can still get them made! Please let me know
