I thought this mod maybe useful for other guzzi owners.
http://www.vtac.co.uk/tacho2.htm
I purchased a Cali 3 recently which had been converted to lucas rita electronic ignition. This has no signal to drive the electronic tacho. Fitting the tacho interface enabled me to take a feed from the coils and get the tacho running. The clever part about this device is that you can set the number pulses outputted to the tacho per spark signal. The Lucas ignition uses a " wasted spark", so I set it to one pulse 1 out for 2 pulses in. I thought this may help others with tacho issues.
Allan (UK)