Wednesday, August 7, 2013


When I first cranked it up I noticed the electronic tachometer was hardly moving off zero. After much thought I came to the conclusion that with dual points and coils the tach was getting one pulse per two revolutions of the crank. The tach thinks it is setup for a two cyl. engine and should get 2 pulses per 2 revolutions of the crank. I was advised on the Yahoo Replicas forum to add 2 diodes to the coils so that the tach would get the 2 pulses it needed without causing the other coil to fire when it wasn't supposed to. Thanks David. The pic should show how it's done. I'll neaten it up with shrink wrap tubes later.

The next issue was getting the electronic speedometer working. These use a pulse generator that fastens onto the tranny where the speedo cable was attached. With the Guzzi metric threads I could not find a pulse generator to fit so Classic Instruments fixed me up with a magnetic pulse sensor. This is mounted on the front upright and counts the spokes on the brake rotor. This seems to work when I spin the wheel by hand. I'll have to go through their setup procedure to calibrate it.

I paid $85.00 for the sensor. Do a search for "cherry gs1007" and you can find one for 30 bucks.

UPDATE: June, 2014
I burned out 2 of these units before I realized I had bundled the wires next to the spark plug wire. It looks like voltage spikes were getting into the sender and causing it to fail.

1 comment: