Won't work with the AGM or a lead/acid battery (on the Pantah IOM replica). Or with several different new/used same regulators.

Seems too simple to not work.

MikeV

Same problem again flattop, on the TT2 build. This time with a Shorai Lithium battery. Tried on three types of batteries. This just seems so simple that it could not fail to work, but it does. A great big mystery. MikeV

Good morning Mike...
I've looked at wiring diagrams for the Sport, Paso and F1. These are some observations I made comparing the wire pairings in your pictures. The wires on the small reg. are paired side by side. Where as the large reg. they are criss crossed. Compared to the Sport work shop diagram, you've got the third alternator wire paired with the solenoid wire#4 and the fused wire#6 paired with the warning light wire#5. The bikes are all wired kind of differently but it appears that the Sport has the most direct route from the battery to the starter. Maybe this will help solve the problem. The diagram is for the Sport.

E.D. After seeing the picture blown up 300% I see that the warning light wire is not paired to the fused wire.

Hey Mike...
Are you using a three wire or two wire stator?

These older pantah engines I have built have the two-wire stator. And many of the later 2-valves models (750s and 900s) also had only two yellow wires, and even some of the 4-valves. The diagrams (several in Haynes 2-valve and 4-valves manuals) even show the regulator wires numbered 1 thru 6, and those are the ones (regulators) I have tried to use. Extra grounding does not help. It just seems that if I used one of the diagrams for a six-wire regulator, that would work. Just does not. MikeV

I've been trolling around the WWW trying to get educated about regulator/rectifiers. Thought I was getting a handle on it until I came across this. Oh my head!
Flattop.