Mostly bikes uses Internal Combustion Spark Ignition(4 stroke) Engines but According to the power output requirement, there may be a few classification on engines as follows:
1.Single cylinder Engine: most of the bikes for mango man e.g. Hero Passion , Honda dream yuga, Yamaha RX100, etc.
2.Two cylinder or Twin cylinder or V Engine:Dream bikes Harley-Davidson VRSC and many more.
3.Turbocharged and supercharged: Honda CX series.
Though bikes with three, four, six, eight, ten and even with 48 cylinder exist but are manufactured less in number.