Why Does my Starter Just go Click

You may have heard of “Startus Interuptus”, its a term they use on the Wild Guzzi forum for failure to start.

It takes a very strong magnetic field to engage the Bosch or Valeo starters on our Guzzis. To produce this strong field there are two coils inside the solenoid not one as the schematic in the manual shows.
One of these coils draws 10 Amps but the other one will draw 40 Amps if you let it, yes a total of 50 Amps, 600 Watts at 12 Volts but only for a fraction of a second, as soon as the large solenoid contacts close they bypass the heavy current coil dropping the current back to 10 Amps.

Unfortunately the Guzzi wiring even on a new bike is not capable of providing the current the starter would like, there is too much resistance in the long path through the wiring and ignition switch.
The switch resistance gets higher over time as the grease gets hard, eventually it may get so high the solenoid just sits there overcome by mechanical load and all you hear is the dreaded relay click, the fuse often blows at this point just to confuse the isue.

What can you do about “Startus Interuptus”?
First of all clean the ignition switch and re-lube it with Vaseline (no fancy expensive grease please), make sure the Start relay is in good shape and the base is making good contact with the relay pins to provide as much current as possible to the solenoid.
The single best move you can make is bypass the ignition switch, feeding a wire direct from the battery via an in-line fuse straight to the start relay 30 contact (this happens to be a yellow wire on the more modern bikes like a Norge or Griso)

How do I know all this?
I have made a study of the Bosch and Valeo starter circuits.
To prove my theory I did a simple test on one of my California Guzzis, first of all I cleaned the ignition switch and all the connection points hoping to make the wiring as close to perfect as possible.
To measure the current I wired in a high current shunt with an Oscilloscope. (events happen too fast to measure with a normal ammeter).
I found it took 40 milliseconds between the instant I pressed Start and when the motor started to crank. The current peaked at about 30 Amps Next I bypassed the ignition switch with a wire from the battery to Start relay as I described above.
I found it now only took 20 milliseconds from pressing start to cranking, (twice as fast). The current inrush was also higher by about 10 Amps.
I also simulated what can happen when the solenoid is unable to pull in, the 15 Amp fuse popped in less than half a second.

Why did the bike get wired that way?
I don’t think the factory know about the second coil and they think the solenoid only draws 10 Amps (that’s what you would measure with a regular meter), how else can you explain the single coil on the schematics and the 15 Amp fuse, remember too, they only see brand new bikes with pristine wiring components. The trouble starts to show after a couple of years on the road.

What Guzzis can catch “Startus Interuptus”
Only the ones where the feed to the Start relay is fed through the ignition switch
All the later VIIs, Griso, Norge, Breva, I haven’t seen a V7 yet

Nice post Kiwi Roy, and welcome. This is a historic fault and fix, I did it to my bike many years ago. Another good dodge is to add relays to the headlamp circuit and the main dip switch to remove all high loads from the handlebar switches. It sounds like you have access to better measuring kit than me though, I still rely on a bulb on two bits of wire! :confused:

Kiwi Roy, my Breva 1100 relay doesn’t go click but the starter motor goes “choonk”. I used to have the click but bought one of the “MPH solution” adapters which cured the startus interuptus. But if I leave the bike unridden for a week or two, I get the “choonk”. Only solution is to connect the CTEK charger the night before a ride.

Yes Mackers, the “choonk” you hear is probably the solenoid engaging the gear but the battery doesnt have enough grunt to turn the motor. Measure the battery Voltage right on the posts while you push the button, it shouldn’t drop much below 11 Volts.
If it looks ok there also check it right at the motor and ground it should be the same Voltage as above.

My old California II does something similar, drops down to about 7-1/2 Volts, thinks about it for a couple of seconds then reluctantly starts, on its 8 year old battery, time for a new one.

There’s a lot of different faults that can occur in the starter, some times it takes a while to pin it down.

Yes it makes a huge difference to the light brightness. On bikes with a headlight relay already you can go with a single relay in the headlight energised for high, de-energised for low.