OMC/yamaha ignition timing curve 3 cylinder two stroke.

Hi.
Has anyone seen or measured the timing curve for a three cylinder twostroke standard ignition cdi system? E.g. yamaha or OMC, Ideally for the phealon system used by VolvoPenta 70 hp built only some years around 1978. Typically only some sort of static setting setting is documented but I would like to see how much it is retarted at high revs and also perhaps spot a overreving remidy.
Regards from a rainy Sweden,,,,

I was thinking about how to do this the other day..
I need a signal/trigger that is TDC, so I can compare it to the ignition timing trigger.

all jet ski ignitions have rpm retard ( due to better exhaust I'll bet), outboards could do with it as well, once you pump up the comp and revs