Variations in Mileages

Hello Fellow GSers,
Just completed a four-day trip to Scotland and completed over 1400 miles. I rode on my F650GS single twin-spark, alongside a friend who rode his K75. We covered the same distance but our two odometers had 63 miles difference in the end. That's a lot to be out. Anyone got any ideas on what I might check to try to improve the accuracy? RobA.

4.5% error pretty good, even if speedo superbly calibrated tyre wear would account for that.

My Dakar used to lose a mile or two every time the ignition was switched off.

So, did you stop 63 times?

The older BMW is likely to have a much higher margin of error in speedo read out compared to a newer bike, as much as 10%, to say less than 5% on a newer machine.

For example, a friend of mine on an old K series bike (>15 years old) had an error of approx 10% across the whole speedo range. Whereas the last 3 BMWs I've had, all manufactured since 2006, have all had a similar error, between 1 to 2 mph up to about 50 mph which increased to about 3 mph at about 80 mph.

This kind of speedo error would easily account the the odometer difference over 1400 miles.

Bob