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On the move: Capriolo 75 and Capriolo Cento 50
Trentino four-stroke – Capriolo 75 and Capriolo Cento 50
Content of
Unusual engine designs with vertical shafts and cam disks were once built in Trentino. There was even a two-cylinder boxer among them.
M.ith a vertical shaft boxer, the connoisseur combines the elaborate and extremely rare pre- and post-war racing machines from BMW. A road machine of this type was not built by BMW, but south of the Alps. A two-cylinder four-stroke engine, the Capriolo Cento 50, came from Italy at the beginning of the 1950s, and it had precisely this design feature. The secondary drive, however, took place via a chain.
Founded in 1908 by Count Gianni Caproni, the Aero Caproni company had built airplanes, cars and engines until the Second World War and had to look for a new field of activity at the end of the 1940s. In 1948 the company based in Arco di Trento began building OHV four-stroke single cylinders with 50 cm³ and brought them onto the market under the model name Capriolo, which translates as roebuck and is reflected in the logo – roebuck in front of the alpine panorama. They wanted to stand out from the sister company Caproni Vizzola, which provided motorcycles with NSU built-in engines in Ticino. In 1951, a 75 single-cylinder with an unusual valve control was created in Trentino. A vertical shaft led from the crankshaft via bevel gears to the cylinder head, but did not drive a conventional camshaft there. At its upper end there was rather a cam disk, i.e. a disk with two concentric circular paths with elevations that functioned as cams and actuated the V-shaped valves in the hemispherical combustion chambers via the two rocker arms. Richard Kuchen had already used this system in Germany for the K-Motor or Chater Lea in England.
The 75 single-cylinder series of the first series not only had this unusual valve control, but also a four-speed gearbox operated by a draw key and a fancy rear wheel suspension. A boom on the swing arm acted on the encapsulated springs located under the engine. Friction dampers should fight undercarriage unrest. Only the second series had conventional suspension struts. In addition to valve control, unusual solutions were also found in the engine. With a trick, the connecting rod of the one-piece, longitudinally arranged crankshaft was mounted on roller bearings. The cylindrical rollers could be inserted between the connecting rod and the crank pin through a groove with a screwed-in fitting piece. After removing the rollers, you could slip the connecting rod over the crankshaft throws.
Rivas
Four-stroke boxer engines with vertical shafts were few and far between in motorcycle history. With the Cento 50, Capriolo had one in its range.
In 1954, Aero Caproni used the 75s in long-distance races such as Milano-Taranto with success and in 1955 won the Giro d‘Italia for motorcycles. In November 1953, Capriolo presented the Cento 50, a two-cylinder boxer that doubled the 75 single-cylinder, at the Milan trade fair. He also had the unusual valve control via vertical shafts and cam disks. The short-stroke arrangement with a 47 millimeter bore and 43 millimeter stroke, as with the 75 counterpart, supported the sporty design. While the Cento 50 was still equipped with two Weber carburetors and an Earles fork at the exhibition, the series models received a telescopic fork and a single Dellorto carburetor, which was encapsulated and connected to the cylinders via long suction pipes. Equipped in this way, the two-cylinder swung up to 7.5 HP at 6000 rpm. As with the single-cylinder, the crankshaft transmitted the torque via an angular drive to the multi-disc oil bath clutch and the four-speed gearbox, albeit with a claw-shift gear, and a secondary drive via a chain to the rear wheel.
While the pressed steel frame looked slightly antiquated, the telescopic fork and swing arm with two spring struts demonstrated the state of the art in Italian chassis technology. In the first series, half-hub brakes provided the delay, with the second series from 1955 onwards, full hubs were introduced. Aero Caproni had the elaborate and expensive two-cylinder in its range until 1956, then after a few hundred copies, simpler 125-cc single-cylinder replaced the remarkable design.
Capriolo specialist Hartmut Klingler calls them all his own, from the first 75 to the Cento 50 to the late 125 with an overhead camshaft or cam disc. It was more by chance that he came across the unusual constructions. He had been looking for a Cucciolo engine and responded to an advertisement. On site it turned out that the object was the unknown brand Capriolo. When he removed the valve cover, he discovered the unusual construction and it kindled love at first sight, although it shouldn’t stay with the 75. Little by little, more Capriolos have been added over the years, including the extremely rare Cento 50.
Rivas
Capriolo became famous with 75 cm³, and Capriolo made a name for itself with the Cento 50: the single-cylinder for everyday use, the two-cylinder for travel.
As soon as you get in touch, the 75 Capriolo feels like the proverbial bicycle that can be turned around in the tightest of spaces. It is not just the low weight of less than 100 kilograms, but the ultra-short wheelbase of 115 centimeters that ensures that the 75 model reacts to the slightest impulse when cornering and even tips over into the tightest of turns with playful ease. The seating position, which is close to the wide handlebars, contributes to the feeling of lightness. However, after short bumps in the road, the undercarriage bobs up and down and catches lightly in corners. Sonor sounds the four-stroke single and develops its performance extremely evenly. Without ups and downs, it wanders almost soothingly through the speed range. Moderate vibrations increase in proportion to the speed. The draw-wedge shift alone requires some getting used to, despite the normal shift pattern – first gear down, the rest up. Although the effort required is low, the switching paths are typically long for this design. The narrow half-hub drums decelerate the flyweight appropriately.
The Cento 50 of the second series, already equipped with full-hub brakes, is easy to handle, but not as playful as its little sister. In addition, their turning circle is much larger. It wants to be brought to life with the Kickstarter on the left and surprises with a remarkable sound spectrum. A pressed hard sound escapes from the two small silencers. Despite the rather modest displacement, the Cento 50 sounds like a disproportionately larger volume of work and is much more sporty than a boxer BMW from the same era. The engine sound is more like the sound of an English two-cylinder triumph and is able to inspire you every time you hurry through the rev range. The Cento 50 develops its power evenly without ups and downs and the vibrations are marginal over the entire speed range, as usual with the boxer engine. Your transmission, on the other hand, shifts extremely bony and wobbly, although the driver changes gears with claws. The reverse scheme of the right-hand shift is less of a problem than the long distances and the high effort required on the rocker switch. It is only after a period of getting used to it that the gear change takes place vigorously and corresponding breaks without ugly noises.
Compared to its smaller sister, it is extremely handy in absolute terms, but cannot keep up with the super lively 75 series. On the other hand, it convinces with stable straight-line stability and stays on course even in bends with bumps. Your full-hub brakes decelerate properly when you pull the lever accordingly.
Especially because of its beguiling sound, the small vertical wave boxer inspires and makes you want more. It was without a doubt the highlight of the model range, but the calculation did not seem to work out despite a comparatively high sales price, especially since initial engine damage was gnawing at the image. In 1956 the Cento 50 disappeared from the range again.
In 1956, Aero Caproni had renamed itself Aeromere Trento and introduced a new model range with 75, 100 and 125 single-cylinders, which differed significantly from the previous models. All versions were given a much more modern looking pressed steel frame. In addition, the crankshafts no longer rotated lengthways in the direction of travel. This eliminated the need for deflection with bevel gears, and the design effort was considerably lower. Capriolo retained the design with upright shaft and cam disk. One of the 125 models even had an overhead camshaft. The single cylinders were sold in quantities of several thousand units. Aeromere was also involved in off-road sports and achieved considerable success. But at the beginning of the 1960s, demand fell sharply. In 1964 the plant had to close. Nevertheless, a surprising number of Capriolos survived. Today, in addition to collectors like Hartmut Klingler, there is a loyal community, especially in Italy, which holds the Capriolo flag high and honors the motorcycles with their unusual construction.
Technical specifications
Rivas
Sixpack: Hartmut Klingler has almost the entire Capriolo range in his fleet. Three 75s from the first series to the Sport, the rare Cento 50, the 125 with overhead camshaft and the 125 with a cam disk.
Capriolo 75
Capriolo Cento 50
engine
design type
Single-cylinder four-stroke engine, two valves operated by a vertical shaft, cam disk and rocker arm
Two-cylinder four-stroke boxer engine, two valves each operated via vertical shafts, cam disks and rocker arms
drilling
47 mm
47 mm
Hub
43 mm
43 mm
Displacement
75 cm3
149 cm3
compression
7.5: 1
7.5: 1
power
3.8 hp at 6500 rpm
7.5 hp at 6500 rpm
Mixture preparation
Round slide carburetor, Dellorto, UBS 18
Round slide carburetor, Dellorto, UBS 18/3
ELECTRICAL SYSTEM
starter
Kickstarter
Kickstarter
ignition
Contact-controlled battery / coil ignition
Contact-controlled battery / coil ignition
alternator
DC alternator
DC alternator
POWER TRANSFER
coupling
Multi-panes-
Oil bath clutch
Multi-panes-
Oil bath clutch
transmission
Four speed draw key-
switched
Four-speed, steal-
switched
Primary drive
Bevel gears
Bevel gears
Secondary drive
Chain
Chain
LANDING GEAR
Frame type
Pressed steel frame
Pressed steel frame
Front wheel guide
Telescopic fork
Telescopic fork
Rear wheel guide
Pressed steel swing arm,
Central suspension,
Friction shock absorbers
Pressed steel swing arm, two spring struts
bikes
Spoked wheels with aluminum rims
Spoked wheels with aluminum rims
Front tires
2.25 x 24
2.75 x 17
Rear tire
2.25 x 24
2.75 x 17
Front brake
Simplex drum,
Ø 120 mm
Simplex drum,
Ø 160 mm
rear brake
Simplex drum,
Ø 120 mm
Simplex drum,
Ø 160 mm
MEASUREMENTS AND WEIGHT
Weight
68 kg
105 kg
wheelbase
1150 mm
1300 mm
Performance
Top speed
70 km / h
85 km / h
Construction year
1952
1955
MANUFACTURER
Aero Caproni, Arco di Trento, Italy
Aero Caproni, Arco di Trento, Italy
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