Wow - that's unusual. I'm trying to think what the default state of a voltage regulator is but even flat out, the charging system on these bikes near idle generally won't overcharge. I'm thinking that if the voltage regulator stops operating, it's "failure mode" is to charge more / not less. That could partially explain over-charging but I'm still puzzled. It seems too high.
A failed rectifier will not cause higher voltage (it will cause less).
There are two things I'm curious about. Do you have another meter you can check with (second electrical opinion
)? Other than that, I'm wondering if you have a modified alternator... People have talked about getting parts of their alternator re-wound to make them operate better. These systems are adequate for the bikes but as soon as you start adding additional load (bigger coils, accessories) or the system weakens with bad connections (common), they become less than adequate.
