The Moto-Guzzi Nuovo Falcone VOC

I know this is an old thread, but it was very useful to me in helping getting my old tractor electric starting.  Here is what I ended up doing.  I bought a HC-Cargo 110061 dynastarter.  The drive belt is a SPZ type, 10mm x 645mm.  Now the interesting subject of the pulley.  It is suggested that the correct size is 71mm.  I tried a 71mm pulley.  The starter worked but quite high revs were required for the charge light to go out (over 30mph on the road).  I have retained the original regulator which could have something to do with it.  I ended up with a 60mm pulley.  This gives better torque for the starter and the charge light extinguishes just above tickover.  I was a little worried about overrevving the dynastarter but I figure if the charge light goes out at the correct  revs all should be well.  I got my pulley from Bearing Shop UK (APZ060/1).  They will also machine it for you.  You need a 17mm bore and a 4mm keyway.  £32.99 all in.  As supplied, I found I could get the dynastarter shaft nut on but not the lockwasher.  There is always loktite of course but I prefer belt and braces.  I dont have a lathe but using a woodworking router at low speed with a sharp bit, I reduced the pulley boss by about 4mm to give room for the lockwasher. The original pulley had holes for a holding tool but I found I could tighten the nut well by using a strap wrench to hold it.  I saw the suggestion of using a taper lock pulley.  These are good devices (I used them extensively in a factory years ago) and I did try this solution.  However, I found there was not enough shaft length on the dynostarter for the taperlock to grip.  Yes, it would have worked but only gripping a short length of shaft.  I would not trust it.  On the electrical side, I used the Lucas SRB325 solenoid and a cheap handlebar push switch both of which worked well. I used car battery lead for the heavy solenoid connections and added a similarly heavy earth lead.  I did have a few problems which might have been to do with buying the dynastarter and leaving it on the shelf for 18 months before getting round to the job.  First off, it would not motor.  Ended up spinning it round on the kickstart with the starter button pressed (decompressor in of course) and eventually it got the idea.  Similarly it would not charge but that was not unexpected and was solved by flashing the unit in the time honoured fashion.  All in all a successful exercise and the starter works well, hot or cold.