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MV Agusta 125 Bialbero

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MV Agusta
IndustryMotorcycle manufacturing
Founded1945 in Italy
FounderDomenico Agusta
Headquarters
Italy
ProductsMotorcycles


Template:Infobox motorcycle The MV Agusta 125 Bialbero was a factory racing motorcycle with a 125 cc engine, manufactured by the Italian company MV Agusta from 1950 until 1960. This model achieved significant success, securing victory in 34 Grand Prix races, earning six riders' titles and one manufacturers' championship. Additionally, it claimed four Italian national titles and ten championships in various other countries.

History

In 1949, Domenico Agusta recruited engineers Piero Remor and Arturo Magni, both formerly affiliated with Gilera and instrumental in developing the Gilera 500 4C four-cylinder racer. Leveraging Remor's expertise, MV Agusta advanced the development of the MV Agusta 500 4C, but Remor's initial project involved designing a 125 cc four-stroke engine.

Technology

The term "Bialbero" translates to "two camshafts," reflecting the era's understanding that small-displacement racing motorcycles required dual camshafts for optimal performance. The design of the MV Agusta Bialbero 125 engine bore similarities to the pre-World War II Benelli 250 cc racing machine.

This powerplant was an air-cooled, single-cylinder four-stroke with dual overhead camshafts (DOHC) actuated via a gear train. The valves were arranged at a right angle of 90°, operated by external hairpin valve springs. By the final iteration in 1960, valve diameters measured 34 mm for intake and 32 mm for exhaust. The bore and stroke dimensions were 53 × 56 mm, resulting in a displacement of approximately 123.54 cc—dimensions comparable to those of the Mondial 125 Bialbero rather than the Gilera 500 4C. The compression ratio reached 11:1 by 1960. Initially, the dry sump oil reservoir was positioned beneath the fuel tank but was relocated to the front section of the petrol tank during the mid-1950s. Ignition was provided by a magneto until 1954; from 1955 onward, dual ignition coils were installed with a rocker switch enabling selection between them. Power output rose from about 12 hp in the early years to roughly 20 hp by the end of production.

The transmission featured a dry multi-plate clutch driven via gears from the crankshaft. Early models had a four-speed gearbox, which expanded to seven speeds starting in 1955. Power was transmitted to the rear wheel through a chain drive.

Structurally, the motorcycle utilized a double cradle frame constructed from chrome-molybdenum steel tubing measuring 25 × 1.2 mm in diameter. Initially equipped with girder forks and occasionally Earles forks at the front, later versions adopted telescopic forks. The rear suspension incorporated a swinging arm fitted with friction dampers initially; these were replaced around 1954 with conventional spring-and-hydraulic shock absorber units for improved damping performance.

Technical details

MV Agusta 125 Bialbero 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960
Valvetrain DOHC featuring two valves per cylinder
Engine configuration Four-stroke single-cylinder
Engine cooling Air cooling
Bore 52 mm 53 mm
Stroke 58 mm 56 mm
Engine displacement 123.2 cc 123.5 cc
Compression ratio Not specified 11:1
Lubrication system Dry sump
Max power 12 bhp (8.9 kW) @ 12,000 rpm Not known 15 bhp (11 kW) @ 10,800 rpm Unknown 18.5 bhp (13.8 kW) @ 12,000 rpm Not available 20 bhp (15 kW) @ 12,000 rpm
Top speed Unknown 90 mph (140 km/h) Unrecorded 115 mph (185 km/h) Unknown 120 mph (190 km/h)
Primary drive Gear
Clutch Dry multi-plate
'Gears' 4 5 7

- ''Final drive' '|'colspan=11' 'align=center' |Chain drive

- ''Frame' '|'colspan=11' 'align=center' |Double cradle

- ''Front forks' '|'colspan=2' 'align=center' |'Girder forks '|'colspan=2' 'align=center' |Earles forks or Telescopic forks '|'colspan=7' 'align=center' |Telescopic forks

- 'Rear suspension' '|'align=center' |'Swinging arm with 'friction dampers '|'colspan=3' 'align=center' |Unknown '|'colspan=7' 'align=center' |Swinging arm equipped with hydraulic shock absorbers

- ''Brakes' '|' colspan=11 'align=center' |Drum brakes

- 'Dry weight' '|' colspan=2 'align=center' |Unknown '|'align=center' |76 kg '|' colspan=3 'align=center' |Unknown '|'colspan=5' 'align=center' |80 kg

Timeline

1949

The initial design phase for the new motorcycle began.[1]

1950

The model made its first appearance during the 1950 Dutch TT#Dutch GP in July.[2]

1951

In 1951, Leslie Graham competed using this machine in two events. He retired from the 1951 Isle of Man TT#Ultra Lightweight IOM TT, but secured third place at the Dutch TT#Assen.[3] He concluded the season ranked eighth in the 125 cc category of the 1951 Grand Prix motorcycle racing season.[4]

1952

Graham shifted his focus to the 500 cc class in 1951. Domenico Agusta recognized the value of British riders familiar with the Isle of Man TT Mountain Course#Mountain Course, and the Clady Circuit#Northern Ireland, signing Cecil Sandford for the 125 cc division.[5] Though relatively inexperienced internationally, Sandford had been competing at the Isle of Man since 1948 in events such as the Clubmans Junior TT, Manx Grand Prix#Manx Grand Prix, Senior TT, and Junior TT.[6]

Sandford achieved victories at the 1952 Isle of Man TT#Ultra-Lightweight TT, 1952 Dutch TT#Assen TT, and the 1952 Ulster Grand Prix. He also placed third in both Germany and Spain Grand Prix events that year. Additionally, he set a new lap record at the Isle of Man.[5] The 1952 model weighed just 76 kg and delivered an increased output of 15 bhp. Sandford secured the 125 cc title in the 1952 Grand Prix motorcycle racing season,[7] while MV Agusta claimed the Constructors Championship.[8]

1953

In response to demand from private riders, MV Agusta introduced a simplified version of their 125 cc racer: the MV Agusta 125 SOHC#MV Agusta 125 Monoalbero, featuring a single overhead camshaft.[9] This model quickly gained popularity, resulting in eleven MV machines starting at the 1953 Grand Prix motorcycle racing season#Isle of Man TT.[10] Les Graham won the Lightweight 125 cc event but tragically lost control during the Senior TT at high speed on Bray Hill and died instantly.Cite error: The opening <ref> tag is malformed or has a bad name Sandford finished third, while newcomer Carlo Ubbiali, who had joined MV from Mondial, retired from that race.Cite error: The opening <ref> tag is malformed or has a bad name Ubbiali won in Germany,[11] and Angelo Copeta, riding an MV, won the final race of that season in Spain.[12] Sandford, Ubbiali, Copeta, and Graham took second through fifth places respectively in that year's World Championship.Cite error: The opening <ref> tag is malformed or has a bad name MV Agusta retained their constructor's championship.[8]

1954

The NSU Motorenwerke#NSU Rennfox dominated early in the 1954 Grand Prix motorcycle racing season, led by Rupert Hollaus, who won the first four GPs.[13] Carlo Ubbiali placed second at the Lightweight 125 cc Isle of Man TT but retired during the Ulster Grand Prix.[11] Following Hollaus's fatal accident during practice for the Nations GP at Monza,Cite error: The opening <ref> tag is malformed or has a bad name NSU withdrew from competition.Cite error: The opening <ref> tag is malformed or has a bad name Ubbiali secured third place at Monza,[11] earning enough points to finish second overall in the world championship.Cite error: The opening <ref> tag is malformed or has a bad name

1955

With NSU's departure, MV Agusta asserted dominance over the 125 cc category throughout 1955 by winning every GP that season. Luigi Taveri claimed victory in Spain's opener, while Ubbiali won all subsequent races.[14] The top three positions in that year's world championship were held by MV riders: Ubbiali, Taveri, and Remo Venturi.Cite error: The opening <ref> tag is malformed or has a bad name MV Agusta also secured another manufacturers title.[8]

An enlarged variant called the MV Agusta 175 Bialbero was produced for participation in Italy's popular 175 cc Championship series.[14]

1956

Competition intensified during the 1956 Grand Prix motorcycle racing season, notably from Gilera’s new 125 GP ridden by Romolo Ferri and Mondial’s updated 125 Bialbero piloted by emerging talent Tarquinio Provini.[14] Ubbiali triumphed in five out of six GPs,Cite error: The opening <ref> tag is malformed or has a bad name clinching his championship title while teammates Taveri and Fortunato Libanori finished third and fifth respectively.Cite error: The opening <ref> tag is malformed or has a bad name MV Agusta again captured the constructor’s crown.[8]

1957

By 1957, Mondial had enhanced their machine to produce approximately 18 bhp.[14] Ubbiali began strongly with a win at Hockenheimring,[11] though Provini recorded the fastest lap time.[14] Provini then won three consecutive GPs—the Ultra-Lightweight TT, Dutch TT, and Belgian GP.[15] Meanwhile, Taveri secured victory at Ulster and Ubbiali triumphed at Monza.[11] Ultimately, Ubbiali finished second overall with Taveri third in that year’s championship.Cite error: The opening <ref> tag is malformed or has a bad name

1958

At the close of 1957, leading Italian manufacturers Gilera, FB Mondial, Moto Guzzi, and MV Agusta announced withdrawal from Grand Prix racing due to escalating costs disproportionate to sales benefits.Cite error: The opening <ref> tag is malformed or has a bad name However, Count Agusta reversed this decision and continued participation into the 1958 Grand Prix motorcycle racing season. The MV Agusta team featured Carlo Ubbiali and Tarquinio Provini as riders. Ducati entered with Alberto Gandossi and Luigi Taveri competing.[14]

Ubbiali secured victories at both Isle of Man Lightweight TT and Assen,[11] while Ducati achieved its first win at Spa-Francorchamps.[16] After a German GP win by Ubbiali,[11] Ducati introduced a new machine for Sweden featuring Fabio Taglioni’s innovative four-stroke single-cylinder engine equipped with three overhead camshafts to facilitate desmodromic valve operation.[14] The Ducati Desmo immediately proved successful as Alberto Gandossi won comfortably,[16] though he later crashed at Ulster allowing Ubbiali to claim victory there.[11] Bruno Spaggiari took Ducati’s final win of the season at Monza.[17] Ultimately, Ubbiali claimed that year’s championship with Provini placing fourth. MV Agusta retained their constructors title.[8]

1959

The MV Agusta team dominated throughout the 1959 Grand Prix motorcycle racing season. Provini won races at Isle of Man and Sweden,[15] while Ubbiali took victories in Germany, Assen, and Spa.[11] These results secured Ubbiali’s championship title early enough for MV Agusta to skip competing at Ulster. In Monza’s home race, however, Ernst Degner unexpectedly defeated them on an MZ RE 125 powered by a two-stroke engine.[18] Ubbiali finished as champion with Provini second,Cite error: The opening <ref> tag is malformed or has a bad name and MV Agusta once more earned their constructor’s championship.[8]

1960

Honda made its debut in the 125 cc class during the 1960 Grand Prix motorcycle racing season.[19] The MV Agusta 125 Bialbero now produced around 20 bhp with a top speed near 120 mph (200 km/h), while Honda’s RC143 delivered a higher power output of approximately 23 bhp thanks to its two-cylinder design undergoing rapid development,[19] although it remained slower than both MV Agusta and MZ RE 125 machines.[14] Ubbiali won four out of five GPs[11] securing his final world championship with teammate Gary Hocking finishing second.Cite error: The opening <ref> tag is malformed or has a bad name

The year marked the end of production for the MV Agusta 125 Bialbero as escalating expenses—primarily due to investments focused on their larger-displacement racers—led Count Agusta to discontinue participation in the 125 cc class thereafter.

References

  1. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named MVagusta-Oldtimers 125 Bialbero
  2. ↑ Büla & Schertenleib 2001.
  3. ↑ Chamberlain 1952.
  4. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named motogp.com 1951
  5. ↑ 5.0 5.1 Chamberlain 1953.
  6. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Cecil Sandford results
  7. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named motogp.com 1952
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 Cite error: Invalid <ref> tag; no text was provided for refs named Overwinningen
  9. ↑ Walker 1998.
  10. ↑ Büla & Schertenleib.
  11. ↑ 11.00 11.01 11.02 11.03 11.04 11.05 11.06 11.07 11.08 11.09 Cite error: Invalid <ref> tag; no text was provided for refs named Carlo Ubbiali career statistics
  12. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named motogp.com · Angelo Copeta
  13. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Rupert Hollaus career statistics at the MotoGP Homepage
  14. ↑ 14.0 14.1 14.2 14.3 14.4 14.5 14.6 14.7 [[#CITEREF|]].
  15. ↑ 15.0 15.1 Cite error: Invalid <ref> tag; no text was provided for refs named Tarquinio Provini career statistics
  16. ↑ 16.0 16.1 Cite error: Invalid <ref> tag; no text was provided for refs named Alberto Gandossi career statistics
  17. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Bruno Spaggiari career statistics
  18. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Ernst Degner career statistics at MotoGP.com
  19. ↑ 19.0 19.1 Cite error: Invalid <ref> tag; no text was provided for refs named Kortekaas

Bibliography

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