On the move: BMW R 100 S, Honda CB 900 F Bol d’Or, Moto Guzzi Le Mans I.

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On the move: BMW R 100 S, Honda CB 900 F Bol d'Or, Moto Guzzi Le Mans I.

On the move: big bikes from the 70s

BMW R 100 S, Honda CB 900 F Bol d’Or, Moto Guzzi Le Mans I.

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At the turn of the decade, MOTORRAD CLASSIC brings the big dreams of the 70s back onto the stage.

In the Swabian Alb, the end of November usually means winter weather. Today, however, the sun has risen again vigorously, breathes a mild breeze over the mountains and dries the winding roads in no time. The tires of the BMW R 100 S, Honda CB 900 F Bol d’Or and Moto Guzzi 850 Le Mans are dreamy terrain: curves, hairpin bends, hilltops – the finest motorcycle country.

The test team maneuvers the classics out of the van as carefully as if the robust horseshoe were baked from fragile puff pastry. A lot can happen, but just no quirks, no scratches, no dents. After all, all three loans are in the best condition, even if they are not always in a standard condition. For an authentic journey through time, it does not matter whether an exhaust has black paint or shiny chrome, whether a brake line is coated with flexible steel, contemporary retrofit struts are installed or whether every brushstroke is accurate. We want to feel, hear and feel the machines that have meanwhile matured into classic cars – in short: experience them anew. That is exactly why they are on the latest tires, the BMW and Moto Guzzi on the brilliant BT 45 from Bridgestone, the Honda on Metzeler Lasertec. It would be soulless to retell yellowed archive material and third-hand anecdotes, which is why MOTORRAD CLASSIC drives and listens.

The leather jacket just extends over the thick sweater; Zip up, open your helmet – and off you go. No way: The engines require a sensitive machinist who knows how to play with choke and throttle. Anyone who turns the gas with a gross engine or moves the cold start lever in the wrong direction has bad cards. But talented or trained hands harmonize ignition and mixture, the crankshafts get on their toes, the engines cough free.

The Munich version of the sports motorcycle theme: BMW R 100 S

BMW telescopic fork with front axle mount; pivoting brake callipers.

In this review, the R 100 S represents the white-blue colors, although the wind tunnel wonder R 100 RS was in the sales rooms at the same time. Weather protection or aerodynamics: the classic variant that was the legitimate successor to the sporty R 90 S is and will remain the slim R 100 S.

This is exactly how the test drivers in MOTORRAD 1/1979 saw it: “The silver giant R 100 RS, nicknamed the regatta sailor, may well serve as a prestigious item for Bavarians, but it hardly meets the requirements of committed motorcyclists. The sporty R 100 S is more likely to do that. ”

Oh yes, she can do it. Its boxer engine is made for jagged speeding around corners, offers full thrust from 1500 rpm and a power range as wide as the dialect of the Swabian Alb. If need be, the two-valve engine cheers at speeds at which the bumpers dance rock‘n’roll. Because the motor configuration enables excellent mass balancing, the vibrations are kept within limits. Only in the very low speed range or with poorly synchronized carburetors does the two-cylinder shake a little indignantly.

BMW put lavish 40s Bing carburettors on the intake manifolds of the big boxers, which thanks to the vacuum-controlled throttle valves go down gently in all positions. In the motor housing there is space for the air filter element, which protects the R 100 S from tuning capriols: No swallowing, no power loss, no magic with nozzles and needles – just pull on the gas and off you go.

Patience is only required when changing gears, as the relatively fast-rotating gearbox loudly acknowledges claws that are pushed in with a metallic ratchet. Apart from that, you make friends with the first-class boxer quickly. Anyone who also comes to terms with the up and down of the cardan shaft and long-stroke telescopic fork, which takes a bit of getting used to, holds the stalls tightly under tension when cornering and conducts calmly and smoothly, has a lot of fun. The ingenious ergonomics make a decisive contribution to this: the perfectly cranked tubular handlebar, which is also often screwed onto Japanese motorcycles, an almost English relaxed knee angle and a harmonious knee joint on the slim tank weld the driver and his pedestal into a dynamic ensemble.

BMW R 100 S: one of the most beautiful boxer models with consistently classic lines.

Chassis developer Hans Gunther von der Marwitz and his team had the double loop frame, which was repeatedly stiffened, under control. The boxer chassis hardly had to show any weaknesses. Today it would be almost inconceivable to weld conically drawn, oval-shaped frame tubes that are adapted to the flow of forces. Even then, the BMW models had a bolted rear frame. In contrast to most Japanese machines, tapered roller bearings carried the two-arm rear swing arm, and the head tube and wheels also turned in high-quality, zero-play adjustable roller bearings.

BMW used an in-house telescopic fork with 200 millimeters of spring travel and mounts for the pivoting swivel calipers. The axle mount was set forward – unusual for a street motorcycle. Perforated 260 mm brake discs decelerated the 237 kg BMW with a full tank of fuel excellently by the conditions at the time. In order to perfect the chassis to perfection, the home-and-yard supplier Metzeler put the grooved and block C tires, unmatched at the time, over the wire-spoke wheels. The customer also received cast aluminum wheels for 985 marks extra. Their delicate cast spokes imitated the double crossed pattern of the wire spoke wheels.

The bottom line was that the 10,990 mark expensive R 100 S and the other R 100 models pulled out of the affair against the Japanese. Fogged up instruments, the saved steering damper and the poor cold running properties, which were due to the poor US carburetor setting, caused displeasure, but MOTORRAD tester Helmut Kokoschinski gave the R 100 S top marks in 1978: “It is a problem-free motorcycle that runs on the A lot of driving comfort on the motorway and the corresponding driving pleasure on the country road. She is one of the safest representatives of her guild. ”30 years later, the MOTORRAD CLASSIC editorial team unreservedly endorses this judgment and wishes Martin Eisleb, the lender of the R 100 S, many more nice trips with his BMW.

Technical specifications

The boxer engine offers the advantage of excellent mass balance. First and second order mass forces can be completely eliminated.

Engine:
Design: Air-cooled two-cylinder four-stroke boxer engine, an underneath camshaft, two valves per cylinder, bumpers, rocker arms    
94.0 mm bore    
Stroke 70.6 mm    
Cubic capacity 971 cm3    
Compression 9.5: 1    
Output 65 hp at 6600 rpm    

Mixture preparation
Two Bing constant pressure carburetors, Ø 40 mm

Electrical system:
Starter electric starter
Battery 12 V / 28 Ah
Ignition Contact-controlled battery ignition
240 W alternator

Power transmission:
Clutch: single-plate dry clutch
Transmission: five-speed, claw shift
Primary drive: helical toothed gears, i: 2.07
Secondary drive cardan, 11:32 teeth

Landing gear:
Frame design: double loop frame made of tubular steel
Front wheel guide: telescopic fork, Ø 35 mm, spring travel 200 mm
Rear wheel guide: two-arm swing arm, two spring struts, spring travel 125 mm
Wheels: wire spoke wheels with aluminum rims    
Front / rear tires 3.25 H 19 / 4.00 H 18
Front brake: double disc, Ø 260 mm
Rear brake: Simplex drum, Ø 200 mm single disc,
 
Mass and weight:
Wheelbase 1465 mm
Steering head angle 62 degrees
Trail 90 mm
Weight 237 kg
Tank capacity 24 liters; 3.5 reserve    

Performance
Top speed 196 km / h

price: 10990 marks (1979)
Manufacturer: BMW AG, Munich

The sporting attack on the Europeans was called the Honda Bol d’Or

The slim appearance is deceptive: At 260 kg, the Bol d’Or is not a lightweight.

The attack did not come as a complete surprise, after all, behind the CB 900 F Bol d’Or there is a lot of experience with the long-distance racing machine RCB 1000. In 1978, Honda presented the 900er at IFMA, and the name “Bol d’Or” was part of it The basic vocabulary of the motorcycle scene in no time. In the meantime, the legend has already established itself as a young and now even as an old-timer, which a large community cherishes and cares for. Like Peter Eckert, who generously provided us with his copy in excellent condition. Fans can find everything about the four-cylinder classic online on the Honda Bol d’Or board (www.honda-boldor-board.de).

From the very first contact with the CB 900 F, it becomes clear that the Japanese were ready to outstrip European motorcycle manufacturers. This not only applies to the 95 hp engine output, but also to the design in detail: switches, fittings and levers – everything perfectly arranged and of the highest quality. BMW and Moto Guzzi were still using coarse standard screws when the Japanese were already marching towards precision engineering with filigree screw heads, sometimes with a collar instead of washer, and small wrench sizes. Each component fits homogeneously into the overall picture, nothing appears to be attached. The double-piston brake calipers on the Com-Star front wheel, introduced for the model upgrade in 1981, and details such as the small, smooth-running vacuum fuel cock speak volumes, testify to the unrestricted will to build the best motorcycles in the world.

Or the four-valve engine: the slightly long-stroke inline four-cylinder is not only a feast for the eyes, but also a milestone in terms of technology and performance. But the striving for perfection ends with the chassis. The long tank and the underdamped telescopic fork decouple the rider from the motorcycle, watering down what feedback is supposed to nourish confidence for swift cornering. Honda also let itself be carried away with the model upgrade in 1981 to the fashionable trend of the air-assisted telescopic fork, an achievement that a few years later disappeared again without a sound.

Without hacking about the suspension weaknesses of that time, you quickly come to the conclusion: On the Honda you are more of a passenger than a captain. Not only the slightly unstable chassis is to blame, but also a fundamental cornering inertia. In principle, this fact can already be read from the technical data: the high-tech device from the 1970s weighs a solid 260 kilograms of steel, aluminum and plastic. The extent to which the perception of motorcycles has shifted in the past three decades is shown by test driver Reinhard Gutzeit’s conclusion in MOTORRAD 6/1979, which one probably acknowledges with a slight smile today. “As an RCB replica, the Bol d’Or is trimmed for sportiness: light and fast.”

The oil cooler always ensured comfortable temperatures for the 4.5 liters of lubricant.

Whereby: The Bol d’Or was definitely fast. Measured 213 km / h and 4.4 seconds for the standard sprint from 0 to 100 km / h ennobled the CB 900 F to one of the fastest motorcycles in the luxury class. Last but not least, it owes these values ​​to its finely adjustable oil bath clutch and the smooth five-speed gearbox, which can be shifted through at lightning speed at full acceleration. Such virtues shaped the image of the Honda, which was then 8,853 marks. As a fast, reliable touring motorcycle and less dedicated to the pure teaching of the sport, many Bol d’Or lugged around large luggage systems and massive crash bars. The only drawback: without balancer shafts and rigidly mounted in the frame, the four-cylinder massages the driver with fine vibrations via the handlebars, seat and footrests.

It was only light, stiff special chassis that helped the Honda to achieve its real purpose, pure sportiness. Tuning gurus like Roland Eckert and Fritz W. Egli linked the glorious name Bol d’Or with racing successes, which did not detract from the popularity of the CB 900 F and prompted MOTORRAD tester Reinhard Gutzeit to conclude in 1979: “With the Bol d’Or Honda hit the mark. “

Technical specifications

After the CBX six-cylinder, the 900 engine was the next multi-cylinder with four-valve technology in the sporty Honda range. In connection with the valve actuation by two overhead camshafts and bucket tappets, it gave the Honda a clear advantage in terms of performance and torque.

Engine:
Design: Air-cooled four-cylinder four-stroke in-line engine, two overhead camshafts, four valves per cylinder, actuated by bucket tappets
64.5 mm bore
Stroke 69.0 mm
Cubic capacity 902 cm3
Compression 8.8: 1
Power 95 hp at 9000 rpm
Mixture preparation: four Keihin constant pressure carburetors, Ø 32 mm, mechanical accelerator pump

Electrical system:
Starter electric starter
Battery 12 V / 14 Ah
Ignition Contact-controlled battery ignition
260 W alternator

Power transmission:
Clutch Multi-plate oil bath clutch
Five-speed gearbox, claw shift
Primary drive tooth chain, i: 2.041
Secondary drive O-ring chain, i: 2.588

Landing gear:
Frame design: double loop frame made of tubular steel
Front wheel guide: telescopic fork, Ø 35 mm, spring travel 160 mm
Rear wheel guidance: two-arm swing arm, two spring struts, spring travel 95 mm
Wheels: Com-Star composite wheels
Front / rear tires: 3.25 V 19 / 4.00 V 18
Front brake: double disc, Ø 276 mm
Rear brake: single disc, Ø 296 mm

Mass and weight:
Wheelbase: 1515 mm
Steering head angle: 62.5 degrees
Trail: 115 mm
Weight: 260 kg
Tank capacity: 20.0 liters; 4.5 reserve

Performance:
Top speed: 213 km / h
price: 8853 marks (1979)
Manufacturer: Honda Motor Co., Tokyo, Japan

On the right track with the wrong concept: Moto Guzzi 850 Le Mans I.

Really Italian: playful instruments, dim lights. The Guzzi has a switchable steering damper for this.

How did you come up with the idea of ​​sending a V2 engine with a longitudinal crankshaft and cardan drive onto the racetrack? The then head of development Lino Tonti answered this question clearly: You reach into the shelf and make the best of a concept that was born for touring.

The first report by MOTORRAD test boss Franz-Josef Schermer in MOTORRAD 24/1976 is, for all its objectivity, a declaration of love to the 850 Le Mans. FJS sums it up: “It just stands there low and crouched, without unnecessary frills, fully designed for uncompromising functionality.” Lafranconi pairs, dipped in matt black as standard, send out clear signals: First, it’s about strength, second, speed, and third, nothing else. That’s why we only notice the weaknesses of the Guzzi very briefly out of the corner of our eye: fragile switch units, paint peeling off the tank, capricious fuel tap. Not worth mentioning if you focus on the essentials. Starting the V2 engine is not a manual operation, not a process, but a real ritual, since the carburettors do not have a cold start device: They have to be flooded with swabs. While the fuel pours over the clutch housing and manifold, two or three turns of the throttle activate the accelerator pumps, which inject an extra portion of gasoline into the intake ducts. The huge electric starter whirls, and shortly afterwards the Guzzi covers entire stretches of land with a thunderous echo that raises the hairs on the neck of people and animals. Because no text, no matter how flaming, adequately describes this concert, moving images and sounds from the 850 Le Mans are stored at www.motorrad-classic.de.

What does the Guzzi have to offer besides the borderline loud sound as early as 1976? On the one hand, the frame, made of short tubes and cleverly designed triangular braces, nestles very closely to the engine. The beams are screwed in such a way that the upper part of the frame can be completely lifted off the motor / gear unit. The cane forms the basis for a chassis that was unparalleled in legend and in real life. As on the BMW, two tapered roller bearings held by threaded bolts guide the short swing arm. Both of them have to do without a continuous swing arm because they would have stood in the way of the cardan joints.

Small deviations from the series: On the original, the Lafranconis were matt black, the struts without a reservoir.

The 35 mm telescopic fork from Le Mans had a solution that was unusual at the time: instead of the conventional piston in an oil bath, closed cartridges worked in the fork tubes. The remaining 150 cm³ of fork oil are only used for lubrication. The advantage: the damper oil pressurized with gas does not foam up, which would have a massive impact on the damping. The Guzzi-specific disadvantages are the poor quality of the damper and the unreliable sealing rings. Today, a “closed cartridge system” is considered a technological achievement in MotoGP and motocross machines.

Moto Guzzi also developed unusual solutions for the brakes. The 300-millimeter-long cast disks, which are acted upon by stiff Brembo pliers, were able to meet the demands of racing. In addition, the engineers from Mandello del Lario were already relying on the integral brake and, when the foot brake lever was operated, passed the pressure on to the left front pliers. The front brake pads with different coefficients of friction ensured that the rear wheel blocked in front of the front wheel. MOTORRAD man Franz-Josef Schermer was enthusiastic about this technology; he suggested using them on other sports motorcycles as well. In principle, Guzzi already offered what Honda is promoting today as the Combined Brake System.

The chassis was above average and the engine was conservative: it is derived from the 750 of the V7 Spezial introduced in 1969. More stroke and a larger bore resulted in 844 cm³. Reinforcing ribs and thicker walls adapted the engine and cardan housing to the power output, which had increased to 70 hp. The valve train with a central camshaft located below, aluminum bumpers and forged, needle bearing rocker arms remained almost unchanged. However, changed control times and larger valve and duct cross-sections allow better filling overall. The rather weak torque curve of the V7 engines was thus eliminated.

Although Le Mans was defeated by the Japanese four-cylinder engines by the bare numbers, the performance demonstrated what it was capable of. With 3.9 seconds from 0 to 100 km / h the 9,695 mark expensive 850 ironed the Far Eastern field to the line and thread. With a top speed of 203 km / h it stayed in the slipstream of the best 750 four-cylinder. The real hour of Le Mans struck where the motorcycle and driver were challenged: on demanding country roads and racetracks. No wonder that Guzzi dealer Peter Lamparth likes to take his Le Mans, our test vehicle, out regularly. After all, the good piece has to be extensively tested before it is handed over to the customer.

Technical specifications

Even if angry tongues trace the origin of the Moto Guzzi-V2 back to a stationary engine and dismiss it with a snappy “cement mixer”, it is simply a historical error.

Engine:
Design: Air-cooled two-cylinder four-stroke 90 degree V-engine, an underlying camshaft, two valves per cylinder, bumpers, rocker arms
Bore 83.0 mm
Stroke 78.0 mm
Displacement 844 cm3
Compression 10.0: 1
Output 70 hp at 7000 rpm
Mixture preparation: Two Dell’Orto round slide carburettors, Ø 36 mm, mechanical accelerator pump

Electrical system:
Starter electric starter
Battery 12 V / 32 Ah
Ignition Contact-controlled battery ignition
240 W alternator

Power transmission:
Clutch: two-disc dry clutch
Transmission: five-speed, claw shift
Primary drive: helical toothed gears, i: 1.235
Secondary drive cardan, 7:33 teeth

Landing gear:
Frame design: double loop frame made of tubular steel
Front wheel guide: telescopic fork, Ø 35 mm, spring travel 125 mm
Rear wheel guide: two-arm swing arm, two spring struts, spring travel 110 mm
Wheels: cast aluminum wheels
Front / rear tires: 3.50 H 18 / 4.00 H 18
Front brake: double disc, Ø 300 mm
Rear brake: single disc, Ø 242 mm

Mass and weight:
Wheelbase 1490 mm
Steering head angle 62 degrees
Trail 110 mm
Weight 225 kg
Tank capacity 22.5 liters; 3.0 reserve

Performance:
Top speed        203 km / h
price: 9695 marks (1979)
Manufacturer: Moto Guzzi S.E.I.M.M, Mandello del Lario, Italy

Conclusion

The Honda has the most power, but the other two big bikes can hold their own.

Each of the three motorcycles from the late 1970s represents a brand and its philosophy. To this day, BMW lives on the independent boxer concept, which reached its peak in the street version with the R 100 S. At most, the first G / S models were as spartan, as honest and as straightforward as they were. The R 100 S was born from the idea of ​​interpreting the sport motorcycle theme in the best possible way using traditionally conservative technology.

The Honda CB 900 F Bol d’Or pursued the same goal with more modern means, but did not quite meet the ambitious goals in terms of chassis technology. Years later, the concept of the in-line four-cylinder should dominate the motorcycle world. The 900 remains, so to speak, posthumously the honor of being a successful pioneer.

The Moto Guzzi 850 Le Mans I made a great appearance in 1976 and set a technical and formal highlight within the V2 series of the traditional brand. It also accentuated its impressive appearance acoustically. The following models lacked the rustic charm of the puristic driving machine. That is why the first version is also considered the true, unadulterated Le Mans.

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