Hi all.

I picked up some K100 spares a month or two ago which inc a better dash/gauges than the one on mine currently.(1983 K100RS, mine has cracked lenses, and digital gear indicator is a black smudge).

Hooked up the replacement unit but the tacho instead of reading around 3500 - 4000rpm at 100kph, the replacement is showing 6500rpm at the same speed of 100kph. 

  Just wondering is it something I can fix easily?  

In the meantime, I put my original set of gauges back on.

Have you considered that the needle in the tacho had been taken off at some stage and not put back on in the right position?

Actually didn't even think about that one.

Alternatively, simply change over the lenses and the GPI component - a fairly straight forward job (just a lot of screws to remove) - remember to pull out the trip odo knob when removing/replacing the lens. That way you get to keep your kms on your current bike odo too and don't have to adopt a random number of kms from your donor bike (there is a way of re-setting the odo, but it is a bit of a fiddly job and them thar odo gears are renown for becoming brittle with age and breaking if you are not careful).

While you're in there, it would be worth checking all instrumentation bulbs are good.

Yep sounds like great advice thank you for your help.