Bit of an update. Tried a couple more things as its stopped raining for an hour or so.
Wrapped 10 turns around the HT lead to see if the rev counter would detect an induced pulse, as suggested via a PM I received. But no joy.
Tried a BR8ES resistor plug, no difference.
I don't reckon there's any point in trying to use the AC input into the Wassell unit because that would effectively earth the AC feed, which defeats the whole point of modifying the stator to provide full-wave rectification.
So in summary, this appears to be where we are with the SIP speedo:
-Fits in a GP heatset, but not so well in an Li/SX
-Speedo function works excellently with a full Wassell DC conversion and battery, but not the rev counter
-Reports that the speedo works on AC system and so does the rev counter if you fit a resistor plug
-The temperature sensor won't fit under the plug, but you can drill a hole in the head fins
Anyone got anything to add?