Distributor drive gear pin replacement
Moto Guzzi V700, V7 Special, Ambassador, 850 GT, 850 GT California, Eldorado, and 850 California Police models
Gregory Bender's technique
Nearly all of the distributor drive gear pins I've seen were for holes 3 mm in diameter. I replace the 3 mm originals with 3 mm roll pins, 16 mm in length (McMaster-Carr part number 91611A157).
Some distributor drive gear pins are 3.5 mm in diameter. I replace the 3.5 mm originals with 3.5 mm roll pins, 20 mm in length (McMaster-Carr part number 91611A187).
Thanks to Ralf Brinkmann for posting this information on the old Yahoo! Loopframe_Guzzi news group (which has now moved to Groups.io). In Ralf's own words:
The original pin can be replaced by a hollow dowel pinDIN 1481orISO 8752.
Moe Moore's technique
Moe Moore at Cycle Garden uses a piece of old drum brake spoke (the smallest diameter part of the spoke). After he drills out the hole in the gear and the shaft a little. The original pin measures 3 mm or 0.138 inch, the spoke measures 0.14 inch. He then heats up the end of the spoke and peens it over, the same for the other end. He uses a jig, so as not to bend, or damage the distributor shaft in the process.
Craig Sheldrick's technique
Craig Sheldrick measured the hole and found that a 3 mm pin is needed. In Craig's own words:
I decided to try somedrill rodfor use as a new securing pin for the dist drive gear. (this rod is very inexpensive, for a 3ft length at 2.95. That will make a lot of pins. This rod is used for shafts, arbors etc., and is machinable, and water hardenable. The only thing is, I've not seen it in metric size, (at least not here), which means the hole will have to be enlarged to 1⁄8 inch. Although I'm sure it's available in metric sizes.
I'm going to make an extra long pin that I can put the hole and easily take out for set up purposes, in order to obtain the correct amount of shims.