Don't Let Out the Magic Smoke

[Kiwi_Roy]

Most old Guzzis have a lot of unfused wiring, if you look at these two for example the fat red wire to the ignition switch and the brown wire back to the fuse box don't have any short circuit protection.
http://www.thisoldtractor.com/guzzi007/schematics/1978_LeMans_II.gif
http://www.thisoldtractor.com/guzzi007/schematics/1981_California_II.gif
As a sparky this makes me cringe, the thought of 200 or 300 Amps running amuck, I always add a big fuse at the battery end 30 or 40 Amps if I can find one, it should never ever blow.
I think it's quite acceptable to have a foot or two of unprotected wire to a fuse block but the wire shouldn't be in a loom where it can melt into others.
This old girl for example has a main fuse although fuses of the era were't anything to write home about.
http://www.thisoldtractor.com/guzzi007/schematics/1971_V7_Sport.gif
The main starter cable is ok as well, it can drain the battery before any serious damage is done.

The fuse also makes a handy way of disconnecting the battery for minor wiring repairs.
The now fused source at the ignition switch is a handy spot to power headlight relays to boost the lighting.

[fossil]

Well... 30 or 40 A? Think again! Let the starter motor be of a 500 W type. 12 V supply voltage then equals nearly 42 A. Inrush current not taken into consideration. I know a lot of vehicles that have no fuse in this circuit.

Correction: Ok, taking a look on the schematics I see you are right. In the first moment I thought of the direct connection via the starter solenoid from the battery to the starter motor.