In our Motorcycle World, we have the choice of many:
Vertical Single.
Vertical across the Frame Twin.
In-Line Twin.
Horizontally opposed Twin.
Across the Frame Vee-Twin.
In line Vee-Twin.
Vertical Four.
Across the Frame Four.
Horizontal Four.
In line Vee-Four.
Across the Frame Six.
Wankel Rotary.
....plus a few more which don't immediately spring to mind... and a few exotic ones!...(Radial!)....

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Each type has its different characteristics.
I've had a various selection of many of them from the past!... and still ride a few, every day!...

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My favourite cylinder arrangement, presently, is the in-line Vee-Twin....(Ducati, etc)....(excites parts not generally exposed to the Sunlight!)....

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Paul The Biker Extraordinaire!...... 8-)...!
http://en.wikipedia.org/wiki/Motorcycle_engine
Win 8.1 64-bit. DX11. Advent Tower. Intel i7-3770 3.9 GHz 8-core. 8 GB System RAM. AMD Radeon HD 7700 1GB RAM. DVD ROM. 2 Terra Byte SATA Hard Drive. Philips 17" LCD Monitor. Saitek Cyborg X Fly-5 Joystick. ...and a Briggs and Stratton Petrol Lawn Mower.