A nerdy thread -
1st up a big thanks to Peter / Kent400 for his tips on damping my ‘750 K2 instruments - oh joy, for the first time in ownership my gauges read something versus everything.
It’s fair job dismantling the instruments, and for the sake of a few minutes I recalibrated both - very accurately.
I used a battery drill to spin the instruments via their own cables, and an iPhone APP to sense the chuck rpm. (taped a magnet to the chuck - iPhone uses internal sensor to give rpm readout.)
Via a little spread sheet with constants (1) front wheel radius and (2) gearing ratios of wheel rpm to speedo drive input rpm ... and (3) crank rpm to rev counter input rpm it converts the drill chuck rpm to both KPH & engine RPM values.
I had to keep the drill spinning at a constant speed whilst I entered that into the spreadsheet. The KPH & RPM values then dictate where you then drop the instrument needle onto its spindle (drill still spinning). A couple of more random drill speeds to double check readings... and the needle(s) can be pushed fully home.
Finally, the speedo needle didn't return to 0 (ie it read 10 KPH at rest) so I then had to gently bend the zero-stop tab down by the speed cap to re-datum 0 KPH.
All now road tested and confirmed accurate via a Radar speed readout board as you enter our village - perfect.
And better still the bike now idles nicely at 1000RPM.... versus the ‘1200’ of past few years.
It all sounds more complicated that it was... Mrs Lobo & I did the 2 instruments in abouts 1/2 an hour....
