I've got the manual (Paso and Sport)
I've got the strobe light
I can see the marks, but that's where the mystery begins.
The rear cylinder seems to be more advanced than the front, which seems backwards to me.

So, What's the proper way to check timing on the 750 motor?
Should I be checking the front or the rear cylinder?
I trust nothing the previous owner has done to this bike.
Magnet Marelli ignition module with vacuum hooked up.

Front cylinder runs lean, and rear runs rich, even after swapping carbs (dellortos). Odd

Thanks,

The way I understand the working of the 90 deg V twin, and when I've watched the valve gear operating, this seems to be the case, the flywheel marks can apply to only one cylinder (which one I'm not sure, and my Workshop Manual says only that the strobe light should be connected to the spark plug, without saying which one). I have only set (and adjusted) my timing statically, going by the way the bike feels under power - when it feels good, that's where I set it. I have the Kokusan ignition.

I also have DelOrtos. If your DelOrtos each have the same jets and settings, I guess that's why swapping them makes no difference. I put a different idle jet into one of my carbs, and synced the carbs very carefully, which made it run really good. It was a long time ago, and I can't remember which carb I changed the jet in, and what size jet it was - sorry. But I reckon each engine has to be set up uniquely, anyway.

The horizontal cylinder is #1 and the timing marks should line up then. The vertical cylinder fires 270* later and there are also marks for that but I don't think you use them for the timing.

The carbs take quite a bit of fiddling to get right.

Good luck.