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Anybody know the point of intentionally running on only two out of
four cylinders?
Related question, how do the non-firing cylinders receive lubrication
without pumping raw fuel/oil out the exhaust at low rpms?

They are firing, and getting a fuel/oil mix. They are just not getting a
sufficiant amount of said mix to actually *combust*, so they remain
"passive" until the revs come up and they start sucking from the main jets.

Why? I've never gotten a totally straight answer. I know that unlike all
the 4 cylinder cross-flows Mercury did, this looper will *not* run correctly
at low RPM on all four. I gather it suffers from harmonics and bad
vibration. And from everything I've read, it's an inherant problem with no
work-around. I don't know what kind of spin Mercury Marketing puts on the
2+2 angle, but the fact is, it was the only way they could make it run right
at all.

Conversely, thier three cylinder 90 (same motor just a three) runs fine at
idle on all three. I think that much like the 90 is kind of 1/2 of the V-6,
that Merc should make the mid-hp motors (100-125) half of the larger V-6's
and scrap that 4. I'll not forget to mention that they had a perfected
100-140hp powerhead untill 1989 when the 2+2 emerged.

-W