Hopefully this is helpful to someone here.
I have had early '80s switch gear and twist grip on both Guzzis. After fighting with the goofy twist grip cable assembly, one of the wire connecters to starter switch broke. :P I resoldered it, but it was a bodge so had to be replaced. This is on an 81 Monza, but other early '80s Guzzis are probably similar.
K&S makes a nice starter-kill switch so got that:
http://www.thisoldtractor.com/moto_guzzi_tonti_handlebar_switch_-_k_s_12-0203.htmlbut the OEM part is one piece - integral with the twist grip - so had to find a dual cable throttle that would work and look OK.
Original one-piece switch and throttle:
I could find, nice, expensive Italian thottles but they are all over 100 clams so found an Emgo 44-29474B that was cheap (Guzzi content) and looked OK, but has some issues (see below):
http://www.emgo.com/images/pdf/2014%20EMGO%20Controls-ebook.pdf
Simplest was installing the new switch. Test fit switch and twist grip:
Pull 4 pin Molex under tank:
Cut off the plug ends of the K&S switch and soldered on new Molex connectors (available at a well-stock hardware store) so that the new K&S switch now has the correct connector.
The order of the wires is marked:
Drill hole for locating pin:
Starter and coil connections can be checked just by plugging in the new switch and hitting the starter - its grounded through the wiring.
The PITA was the twist grip. It has a throttle stop for wide-open, but none for closed throttle. Carb springs will return the throttle, but the twist grip will turn another 1/4 turn past the point where the cables enter the twist grip. This seemed likely to dislodge the cables. The fix was to drill a 1/16" hole through the lower section of the barrel and drive a small nail in to make a stop.
The other issue was that the cable ends are slightly too big to fit through the ferrules. A little filing on the edges took care of that.
The new twist grip and switch installed:
There are 2 things I don't like about the Emgo throttle: no closed throttle stop, and both the open throttle stop and the throttle friction adjuster screws stick out in such a way that they seem likely to tear flesh in the event of an "excursion". However, throttle cable balance is much better. Throttle cables are firmly held in the Emgo twist grip (they are loosely located in the original) and throttle cable synchronizing easier and more consistent. Consequently carb synchronization has been more precise.
The transformation has been dramatic: The bike starts quicker with the new switch despite the fact that the starter relay mod has been done for years and my immediate impression was that it felt smoother and stronger. I celebrated with a 100 mile ride. ;D
