Brian (great name by the way)
go through this before making any assumptions. It comes from the guru (Miti) on the UK site. It may save you some money and a whole lot of hassle.
Old electronics are fragile and XS11 rec/reg units are no exception...
The Spec for the voltage across the battery is 14.5 +/- 0.3 V d.c. @ 2,000 rpm...
If your voltage is lower than that, then you may have connection probs, or a rec/reg that's on it's way out...
But if it's higher, it's probably not the rec/reg unit (unless we're talking about WAY too high) and there's a very good chance that a poor earth connection is causing the regulator to cut off too high... So all may not be lost...
The following is something that should be checked as part of your "routine" maintenance, but may also help if you already suspect rec/reg problems...
Next time you have the tank off, check the earth tags and bolts on the rectifier/regulator...
Clean or replace both bolts
Clean the earth tags to ensure a sound connection
Clean the mounting points on the Rec/Reg unit
Clean out the M6 threads in the frame
And, while you're at it... Check the battery frame earth under the LHS side panel (frame bolt goes rusty and the earth strap actually corrodes through... did on mine anyway...) There is also a frame to engine earth above the middle gearbox that's worth checking...
Why..? This is why...
Techie bit: The corroded terminals develop a voltage across them when current is drawn through them (V=I*R). If this voltage appears at the earth terminal or case of the rec/reg, it's added to the 0V d.c.. reference that the rec/reg unit uses to reference it's output level... So, if a duff connection develops 1V d.c. across it, the reference votage will be 1V and the output voltage will be 1V higher than it should be...
Also: (and FYI) For every extra bit of voltage the Rec/Reg unit outputs, there is a corresponding increase in current drawn (the vast majority of electrical loads on any bike are resistive) If this increase in current is across a corroded terminal, it'll develop a voltage across it... If this appears at the rec/reg unit, it'll increase the unit's output... Which will cause a corresponding increase in current drawn... Seeing the pattern yet..? The end outcome of a dodgy earth connector is usually the early demise of the rec/reg unit... This is usually followed by a boiled dry battery and (for the benefit of particularly persistant offenders) the eventual barbequeing of the alternator stator coils...
If you check all of this out and you STILL have a high voltage across the battery... Try adding an extra wire between the rec/reg mounting bolts & the battery -ve... If it's STILL high, you have a rec/reg fault... If it returns to "normal" than you have an earth fault (probably in the harness) and I would recommend leaving the extra wire in place...
Let us know how you get on.
Brian
