The sound and feel of a V twin come from geometry rather than tuning. The angle between the cylinders determines when each one fires, and that spacing is the whole character.
Firing intervals are set by the vee angle
In a four-stroke engine the crankshaft turns twice per cycle, giving seven hundred and twenty degrees to distribute between the cylinders. A twin with both rods on one crankpin fires at intervals set by the vee angle.
A ninety-degree vee spaces the two power strokes evenly enough to feel comparatively smooth. A narrow angle bunches them together, leaving a long gap before the cycle repeats.
That uneven spacing is what produces the loping idle and the distinct pulse at low speed. It is a geometric consequence, not an effect added by the exhaust.
Balance and vibration follow from the same choice
A ninety-degree vee allows the reciprocating forces of the two pistons to cancel each other more completely, which is why that configuration has a reputation for mechanical smoothness.
Narrower angles leave residual imbalance that has to be managed with counterweights, rubber engine mounts or balance shafts, each of which changes how vibration reaches the rider.
Manufacturers make deliberate decisions about how much to remove. Eliminating all of it produces an engine that many riders describe as characterless, so some pulse is usually retained.
Traction benefits from gaps between power pulses
A tire recovers grip in the interval between power strokes. Widely spaced pulses with clear gaps let the contact patch settle, which is why big twins can put down power on loose surfaces.
This is the same reasoning behind uneven firing orders in modern performance engines, where the goal is feedback the rider can interpret rather than a seamless surge.
The practical result is an engine that communicates the traction limit progressively, giving the rider information before grip is lost rather than at the moment it goes.
Packaging is why the layout persists
Two large cylinders in a vee are narrow across the frame and long fore and aft, which suits a motorcycle chassis where width costs lean angle and length is available.
The layout also puts mass low and lets the frame pass around the engine cleanly, and in many designs the engine itself carries structural loads.
Cooling favors it too, since both cylinders sit in clear airflow, which is why air cooling survived far longer on this configuration than on inline engines.
Why the sound became an identity
Because the firing interval is uneven, the exhaust pulses arrive irregularly, and the human ear reads that irregular rhythm as distinctive in a way an evenly spaced engine is not.
American manufacturers built brand identity around that rhythm over decades, to the point that riders will identify a machine by ear before it is in sight.
Engineering choices that would smooth it out are therefore weighed against what they would cost in recognizability, which is an unusual constraint for an engine designer to work under.