Do all V twin motorcycle engines go 'potato-potato-potato'?
Maybe the 'envelope' of the 'bangs per sec' is similar for each type?

It has to do with firing order, and the logical combining of exhaust
pipes.  A straight six with split manifolds 3/3 like a BMW makes for a
smooth yet sweet sound.  The V-8 "lope" is because the firing order is
generally 1-8-4-3-6-5-7-2 yet the exhaust pipes are combined 1-3-5-7 and
2-4-6-8, so you have the 8-4 and 5-7 pulses right next to each other in
the same pipe, with the delay between 1-3 and 6-2 being longer, so each
pipe gets pulse-wait-wait-pulse-wait-pulse-pulse-wait, 180 degrees out
of phase with each other (well, that's 180 degrees of *cam* but 360
degrees of *crank...* you get the idea, anyway)  if a V-8 is set up with
an even fire exhaust like some old mid-engine racers (GT40 comes to
mind) it sounds a lot like a straight six, but more so, but the exhaust
looks like a bundle of drunken snakes.  A V-12 is basically like two
straight sixes put together, so they sound really smooth as well.

V6's sound like sh.t because there's no natural way to even out a V6 and
also have it balanced.  Four cylinders sound like I-6's but a little
rougher, which you'd expect.  Boxers sound unique, and to be honest I'm
not sure why, maybe it has something to do with the necessity to have
the two main exhaust pipes separated for a while before they come
together (if they ever do.)

Then there's esoterica like how V-8s with siamesed center exhaust ports,
like old flathead Fords, Studebakers, and early Caddys might not be as
efficient as a modern head/exhaust design but they sound oh so good...
something about combining the 3/5 and 2/4 ports makes the exhaust get
all nasty sounding...

nate

Firing order as determined by crankshaft and camshaft geometry, and
placement of the exhaust ports and the related exhaust plumbing.  The
V8, in particular, has its trademark sound because when you build it
with a 90-degree crank (as 99% of street cars are because of balance) it
causes a pair of cylinders on each bank to fire in sequence. IOW, if "L"
represents a cylinder firing on the driver's side (left) bank and "R"
represents a cylinder firing on the passenger's side (right) bank, then
a 90-degree v8 firing order is L-R-L-L-R-L-R-R-L-R-L-L.... etc. The
paired firings on alternate banks cause the "v8 burble" even if the
pipes get plumbed into a single exhaust eventually. There are several
possible physical firing orders for a v8 (for example, aftermarket cam
companies often swap 2 cylinders on the small-block Chevy for better
performance) but ALL the valid firing orders still have that pairing on
each bank at some point during the order. V6 engines don't do that- they
strictly alternate banks like a pair of 3-cylinder engines running
slightly out of phase.

FWIW, a "flat crank" v8 does NOT make that sound. But as I said, most
poeple never hear a flat-crank v8 because they're so rare. IIRC, the
Indy Racing League used (or still uses) flat-crank v8s. I know they did
when Oldsmobile and Infiniti were supplying the engines years back, anyway.