The MV Agusta 125 Motore Lungo (long engine), more commonly known as the "carter lungo" (long crankcase), was a 125 cc, lightweight

two-stroke A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a Thermodynamic power cycle, power cycle with two strokes (up and down movements) of the piston during one power cycle, this power cycle being comple ...

motorcycle manufactured between 1950 and 1953 by

Italian Italian(s) may refer to: * Anything of, from, or related to the people of Italy over the centuries ** Italians, an ethnic group or simply a citizen of the Italian Republic or Italian Kingdom ** Italian language, a Romance language *** Regional Ita ...

motorcycle manufacturer

MV Agusta MV Agusta (, full name: MV AGUSTA Motor S.p.A., original name: Meccanica Verghera Agusta or MV) is a motorcycle manufacturer founded by Count Domenico Agusta on 19 January 1945 as one of the branches of the Agusta aircraft company near Milan in ...

. The machine was often used in racing.

History

MV Augusta started making lightweight motorcycles in 1946. In 1948, a 125 cc class was added to the Italian national motorcycle racing championship (Campionato Italiano di Velocità). MV produced a 3 speed two-stroke machine to compete in this class, the 125 "Valenza". This was superseded in 1949 by the 125 "4 velocita" (4 speed). For 1950, the improved 125 "Motore Lungo" was introduced, which produced 12 bhp @ 9000 rpm.

Details

The term "long engine" derives from the elongated

crankcase In a piston engine, the crankcase is the housing that surrounds the crankshaft. In most modern engines, the crankcase is integrated into the engine block. Two-stroke engines typically use a crankcase-compression design, resulting in the fuel/a ...

in front of the

cylinder A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infin ...

, which housed a special

Magneti Marelli Magneti Marelli S.p.A. () is an Italian developer and manufacturer of components for the automotive industry. The firm is headquartered in Corbetta, Italy, and includes 86 manufacturing plants, 12 R&D centres, and 26 application centers in 19 c ...

magneto A magneto is an electrical generator that uses permanent magnets to produce periodic pulses of alternating current. Unlike a dynamo, a magneto does not contain a commutator to produce direct current. It is categorized as a form of alternator, ...

. The previous model, the 125 "4 velocita", was retrospectively known as the "short crankcase" to differentiate it from the "long crankcase". The engine was an

air-cooled Air-cooled engines rely on the circulation of air directly over heat dissipation fins or hot areas of the engine to cool them in order to keep the engine within operating temperatures. In all combustion engines, a great percentage of the heat ge ...

single-cylinder A single-cylinder engine, sometimes called a thumper, is a piston engine with one cylinder. This engine is often used for motorcycles, motor scooters, go-karts, all-terrain vehicles, radio-controlled vehicles, portable tools and garden machinery ( ...

two-stroke with a

bore Bore or Bores often refer to: *Boredom * Drill Relating to holes * Boring (manufacturing), a machining process that enlarges a hole ** Bore (engine), the diameter of a cylinder in a piston engine or a steam locomotive ** Bore (wind instruments), ...

and

stroke A stroke is a medical condition in which poor blood flow to the brain causes cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop functionin ...

of 53 × 56 mm giving a

displacement Displacement may refer to: Physical sciences Mathematics and Physics *Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...

123.5 cc. The compression ratio was 9:1, and the engine was fed by a

Dell'Orto Dell'Orto is an Italian company, headquartered in Cabiate, specialized in the construction of carburetors and electronic injection systems. The company was founded in 1933 as "Società anonima Gaetano Dell'Orto e figli" (Gaetano Dell’Orto and ...

SS 25 A

carburetor A carburetor (also spelled carburettor) is a device used by an internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to the intake air is through the venturi tube in the main meteri ...

. A Wet

multi-plate clutch A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). ...

was driven by gears from the

crankshaft A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting ...

, and a four-speed

gearbox Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differe ...

sent drive to the rear wheel by

chain A chain is a serial assembly of connected pieces, called links, typically made of metal, with an overall character similar to that of a rope in that it is flexible and curved in compression but linear, rigid, and load-bearing in tension. A c ...

. The MV Agusta had a double cradle frame and girder forks. At the rear there was a

swinging arm A swingarm, or "swinging arm" (UK), originally known as a swing fork or pivoted fork, is a single or double sided mechanical device which attaches the rear wheel of a motorcycle to its body, allowing it to pivot vertically. The main component of ...

with friction dampers.

Drum brake A drum brake is a brake that uses friction caused by a set of shoes or pads that press outward against a rotating cylinder-shaped part called a brake drum. The term ''drum brake'' usually means a brake in which shoes press on the inner surfac ...

s were fitted front and back, 190 mm diameter at the front and 160 mm at the rear. Two versions of the bike were made: the road version, complete with lights, and the sports version, called the "competizione" (competition) model.

Racing

The machine was especially popular in the national 125 cc racing class, where its characteristics of competitiveness and low price appealed to the needs of those who were beginning their career as a rider, and it became the most popular sports bike of the time.

References

{{MV Agusta 125 Motore Lungo Motorcycles introduced in 1950 Sport bikes Single-cylinder motorcycles Two-stroke motorcycles