List of motorcycles by type of engine

List of motorcycles by type of engine is a list of motorcycles by the type of motorcycle engine used by the vehicle, such as by the number of cylinders or configuration.
A transverse engine is an engine mounted in a vehicle so that the engine's crankshaft axis is perpendicular to the direction of travel. In a longitudinal engine configuration, the engine's crankshaft axis is parallel with the direction of travel. However, the description of the orientation of "V" and "flat" motorcycle engines differs from this convention. Motorcycles with a V-twin engine mounted with its crankshaft mounted in line with the frame, e.g. the Honda CX series, are said to have "transverse" engines, while motorcycles with a V-twin mounted with its crankshaft mounted perpendicular to the frame, e.g. most Harley-Davidsons, are said to have "longitudinal" engines. This convention uses the longest horizontal dimension (length or width) of the engine as its axis instead of the line of the crankshaft.
There are many different models of motorcycles that have been produced, and as such, this list is not exhaustive and contains only more notable examples.
Split-single.
The split-single ("Doppelkolbenmotor" to its German and Austrian manufacturers), is a variant on the two-stroke engine with two cylinders sharing a single combustion chamber. It is also known as a twingle, U-cylinder, or doppelkolben<ref name="SPLIT/SINGLES and what they are!">SPLIT/SINGLES and what they are!</ref>
Two cylinder.
V-twin.
Longitudinal.
Lilac 
Murusho
Flat-twin.
Transverse.
Douglas
Straight twin.
"a.k.a. parallel-twin, inline-twin, vertical-twin, straight-two, or inline-two"
Tandem twin.
The Tandem Twin is where the cylinders are longitudinal, and have two cranks geared together. A tandem twin is effectively a pair of geared singles, and is to be distinguished from an inline twin. Tandem twins are suitable primarily for two-stroke racers.
Four cylinder.
This is a partial list of some of the many four-cylinder motorcycle designs.
Wankel.
The Wankel engine is a type of internal combustion engine using an eccentric rotary design to convert pressure into rotating motion. All parts rotate consistently in one direction, as opposed to the common reciprocating piston engine, which has pistons violently changing direction. It is also known as a rotary engine.
Radial.
The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel.
Rotary radial.
The rotary engine was an early type of internal combustion engine, usually designed with an odd number of cylinders per row in a radial configuration, in which the crankshaft remained stationary in operation, with the entire crankcase and its attached cylinders rotating around it as a unit.
Electric.
Electric motorcycles and scooters are plug-in electric vehicles with two or three wheels powered by electricity. The electricity is stored on board in a rechargeable battery, which drives one or more electric motors. 
Diesel.
Only very small numbers of diesel engined motorcycles have ever been built. The improved fuel efficiency is offset by the increased weight, reduced acceleration and potential difficulty of starting, at least in colder climates.