MAP SENSOR
Refers to a manifold absolute pressure sensor, a variable resistor used to monitor the difference in pressure between the intake manifold at outside atmosphere.

MAPPING
Set of reference values stored in the electronic control unit (ECU) memory, used to control the engine operation, especially as far as ignition and injection control is concerned.

Mass Air Flow (MAF) Sensors
The Mass Air Flow Sensors convert the amount of air drawn into the engine into a voltage signal. The ECM needs to know intake air volume to calculate engine load. This is necessary to determine how much fuel to inject, when to ignite the cylinder, and when to shift the transmission.

MECHANICAL INJECTION SYSTEMS
The K-Jetronic system operates by injecting continually, without an external drive being necessary. Instead of being determined by the injection valve, fuel mass is regulated by the fuel distirbutor.

MECHANICAL SUPERCHARGING
The motive force used to power the mechanical compressor is taken directly from the IC engine. Mechanical superchargers are available in a variety of designs. A belt from the crankshsft usually drives the supercharger at a fixed ratio, so crankshaft and supercharger rotate at mutually invariable rates. One difference relative to the turbocharger is that the supercharger rsponds to immediately to increases in rpm and load factor, with no lag while waitig for the impeller to accelerate. The result is higher engine torque in dynamic operation. This advantage is relativized by the power needed to turn the compressor. This must be subtracted from the engine's effective net output, and leads to somewhat higher fuel consumption. However, Motronic can lessen the significance of this by controlling operation of a compressor clutch to switch offf the supercharger at low rpm and under light loads.

Methylcyclopentadienyl Manganese Tricarbonyl (MML)
MMT is an organic manganese compound. It is used as a fuel additive designed to enhance octane levels in gasoline.

METRIC CRUISER
Metric Cruiser is a general category of bikes including Honda, Yamaha, Kawasaki, and Suzuki as opposed to American bikes such as Harley-Davidson and Indian. The American bikes tend to use the English system of measurement: pounds, feet, miles, inches, while the Metric Cruisers use the Metric system of measurement: Kilograms, meters, etc. The fact that some American bikes may use the Metric system to quantify their components may still render them as American rather than Metric, at least in the eyes of the Metric Cruiser enthusiasts. By the way, the new Harley-Davidson V-Rod model is also a Metric Cruiser.

MIXTURE ADAPTATION
The air mass required for the combustion is dependent upon the intake air's temperature. Taking a constant throttle valve setting, this means that sylinder charge reduces along with increasing air temperature. The Mono-Jetronic central injection unit therefore is equipped with a temperture to the ECU which then corrects the injection duration, e.g., the injected fuel quantity, by means of an intake-air-dependent enrichment factor.

MIXTURE CONTROL SOLENOID
Used to control the metering rod, an air bleed, or both. The amount of fuel the solenoid meters depends on how long the solenoid is on during each cycle.

M-MOTRONIC
M-Motronic combines all the electronic systems for engine control in a single control unit (ECU) which, in turn, governs the actuating systems used to control the spark-ignition engine. Engine-mounted monitoring devices (sensors) gather the required operating data and relay the information to input circuits

MON (Motor Octane Number)
The Motor Octane Number, or MON, is derived from testing according to the Motor Method. The MON basically provides an indication of the tendency to knock at high speeds. MON figures are lower than those for RON.

MONO-JETRONIC FUEL-INJECTION SYSTEM
Mono-Jetronic is an electronically controlled, low-pressure, single-point injection (SPI) system for 4-cylinder engines. While port injection systems such as KE and L-jetronic emplou a seperate injector for each cylinder, Mono-Jetronic features a singlem centally-located, solenoid-controlled injection valve for the intire engine.

MONO-MOTRONIC
The Mono-Motronic engine-management system is a low-pressure single-point injection system with intergrated electronic map-controlled ignition. Combinations of the two subsystems enables joint optimization of fuel -metering and ignition-control.

MOTOCROSS BIKE
A light-weight motorcycle specifically designed for racing on a track. As compared to off-road bikes, the suspension is able to handle harder hits, the power delivery is more explosive, and the gear ratios are different for riding on motocross or other closed-course tracks.

MOTORCYCLE
Motorcycles are 2-wheel vehicles patterned after bicycles but with engines and much heavier frames. Early motorcycles were actually bicycles fitted with small internal combustion engines. There was a gradual evolution as numerous motorcycle manufacturers entered the market and competed against each other.
Motorcycles have complex controls that are operated by both hands and feet and require coordination and skill not required to drive an automobile.Motorcycles have been a part of transportation for a very long time. They were once much more prevalent than automobiles until such pioneers as Henry Ford found out how to mass produce cars at a price below that of motorcycles.Over the years, motorcycles have come to fit a variety of needs beyond basic transportation. Today's rider may use a motorcycle for commuting or everyday use.
Some ride as part of their lifestyle. Some ride on lengthy cross-country tours.
Motorcycles have evolved to include 3-wheel vehicles called trikes. Motorcycles are sometimes fitted with a sidecar.In the United States, only one company, Harley-Davidson has been able to survive over 100 years, producing models every year since its first model in 1903. In fact,to most non-motorcyclists, the words "motorcycle" and "Harley-Davidson" are used interchangeably.Although many motorcycle brands exist, the most prominent besides Harley-Davidson are Honda, Yamaha, Kawasaki, Suzuki, BMW, and recently, American made Victory.

MOTRONIC
Motronic combines the gasoline-injection and ignition systems to form a common engine-management system. THe basic fuel-injection systems together with an electrinic ignition form the badis for both the ignition and fuel-injection systems in the Motronic.

MUFFLER
The muffler is a part of the exhaust system designed to reduce the noise generated by a vehicle.

MULTIPOINT FUEL INJECTION
Multipoint fuel injection forms the ideal basis for complying with the mixture formation criteria described above. In this type of system each cyllinder has its own injector discharging fuel into the area directly in front of the intake valve.