My tach jumps up and down and doesn´t go over 2 000 rpm since a few days. On the Swedish forum www.guzziclub.nu
I got three advices; the ground cable from the battery, the relay Bosch 0 332 20 11 07 (isn´t fitted on my bike, mine are
0 332 207 310, 300 or 303) and I´m waiting for an explanaition about that, and finally, there´s a grounding point inside the
tachometer that might cause the problem.
Good luck!
Hej!