Swapped the pickup leads.... no joy. I think I see the problem.
@Paul Sutton theorized (in your thread Jack) that the "amount" of advance is dependent on the relationship between the pickup coil and the size of the iron target. At the time I was thinkin' along those lines also. In the case of the GN250, the pickup is the reluctor (magnet) and the iron target is rectangular shaped.
I've taken the magnet out of this Yamaha pickup so it's not a true reluctor, it's more in line with what we're running on the TCI systems.... a magnetic "target" and a non-magnetic coil to sense the target. So I backtracked a little and reinstalled the magnet in the pickup. That brings us back to rough running, but the advance curve didn't change. It was the same 5 - 10°.
Did some measuring. The Yamaha pickup core is 6mm dia. Compared that to the TCI pickup... it's about 8-1/4 mm. On my SG (TCI) I'm getting about 16-18° advance (Suzuki advertises 25°, so neither one is close to that). I'm seeing a correlation here between the two as far as amount of
time.... no actually, degrees of rotation the coil and target interact with each other vs. amount of advance. That's telling me Paul was on the right track with it being the degrees between the start of the pulse and the end that determines amount of advance.... which explains why Suzuki used an elongated rectangular target when a simple round iron screw would have otherwise been just fine.
I'm mulling over some ideas... but I think this Yamaha pickup leads down a dead end. Keep in mind my two overriding principles here are cost and KISS... keep it simple. For that reason I'm not gonna go down the road of adding resistors, capacitors or what have you, unless there's absolutely no other way.
EDIT: Just realized I forgot to swap the boxes. I've already put everything away 'cause there's rain clouds about. I'll try that tomorrow.