Motorcycle Repair: Triumph T21 - electrical problem, zener diode, little devil

Question
I have a Triumph T21 1966 which, at some point, has had a Boyer solid-state 12v ignition fitted.  The engine has been fully-proffesionally re-built.  I had a fuse-blowing problem last year which an electrician friend fixed - however.  The bike started first time OK but then seemed to overcharge (according to the ammeter).  It then developed starting problems and finally wouldn't start at all.  When I checked the battery it had boiled dry.  I have restored the battery, it is fully charged.  The side light comes on OK when the ignition is switched on but I can't get it started.  I don't think I'm getting any spark at the plugs.  Any suggestions?   PS.  I hope your son finishes his tour OK.  I have some small idea of the stress you're under.

Answer
Jim

Damn, where did all these questions come from? I've got a bunch of 'em. I thought I was listed as on vacation while I was running for the United States Senate.

Don't believe me? Check out my web site:

http://www.senatorjohn.com

I think you might have problems greater than what I can diagnose from this remote location, but one of the cheapest and quickest fixes would involved the Zener Diode.

That little devil controls the charging circuit and if you had a problem (fuse blowing) it is possible that this part has been zapped and is not doing the job. Also check to make sure it is wired in properly.  

This is a quick guess.

Son has returned in one piece recently. I just hope he doesn't have to go back.

John