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Laverda 750SF

     

 

   

 

Make Model

Laverda 750SF

Year

1970-71

Engine

Air cooled, four stroke, parallel twin cylinder, SOHC, 2 valve per cylinder.

Capacity

743
Bore x Stroke 80 x 74 mm
Compression Ratio 8.9:1

Induction

2x Dell'Orto PHF  carbs.

Ignition  /  Starting

Max Power

61 hp 44.5 KW @ 7500 rpm

Max Torque

Transmission  /  Drive

5 Speed  /  chain

Front Suspension

Rear Suspension

 

Front Brakes

2X 230mm drum

Rear Brakes

200mm drum

Front Tyre

3.50-18

Rear Tyre

4.0-18

Dry-Weight

Fuel Capacity 

SF First Version (1970)

This original SF series was built from frame number 3808 onwards. The coding SF (standing for 'Super Freno', or 'super brake') referred to the adoption of entirely new drum brakes designed by the company's founder, Dr Francesco Laverda. (The rest of the design was carried out by Luciano Zen and other members of Laverda's engineering team.) The majority of the production run featured a cylinder barrel-high exhaust connector tube connecting the two header pipes. Except for the brakes, this first SF was virtually identical to the 750S that proceeded it.

SF Second Version (1971)

For the 1971 model year, the SF underwent a number of changes. The most important of these was a change from British Smiths to Japanese Nippon-Denso instruments, a new fuel tank (which no longer had the rubbers for the rider's knees), and an optional lockable storage box incorporated in the racing-type saddle.

Road Test

The name Laverda is fairly new to the American motorcycling public, but the bike has been around for some time, having first been imported to this country as the "American Eagle." The Santa Ana, Calif.-based American Eagle firm is now defunct, but the Laverda is alive and well. Edison Dye, the West Coast importer of Husqvarna, is taking over where the Eagle left off. The flow of bikes and parts from Italy won't be of Japanese-style volume, but the situation is certainly better than no bikes at all. The Laverda is sound, and deserves an American audience.

Could anyone; have imagined three years ago that the Laverda (American Eagle 750S Sport) would be the basis for one of 1971's most successful production road-racers? We'd have been inclined to say not.

However, the sports-minded Italians at the Laverda factory modified their 750, fettled it as a 750cc. production racer and walked away with 1st, 2nd and 3rd places at Barcelona, Spain; 1st, 3rd and 4th places at Zandvoort, Holland, and 2nd, 4th and 5th places at Le Mans, France. These three races were all over 12 hours in duration and the factory-`team of three' machines finished each one with a high placing. Obviously wasn't just luck, and the 750 SF lives right up to them, reputation gained by its production road racer brother.

There are two versions available. The GT, a milder version of the SF, features less compression, milder cams, no exhaust balance pipe, a dual seat, and small detail differences including a slightly less rigid frame and less steering trail to make it more suitable for in town riding and medium speed touring.

The 750 SF, on the other hand, is a sporting man's motorcycle. Low, narrow (26-in.) handlebars, a headlight fairing and a short racing-type seat set the scene and rather rear mounted footrests make the rider feel like he's on a road racer. Quite heavy at 507 lb. with half-tank of fuel, the 750 SF is fairly clumsy at ultra-low speeds but loses this feeling at speeds above 20 mph or so and begins to feel like it should... a sports/roadster with a racing heritage.

Much of the Laverda's handling comes from race-proven frame and steering geometry. A double cradle-type frame with a multitude of top tubes supports the engine at the cylinder head with four mountings and the rear of the crankcase/transmission casting with an additional four mountings. There are no front down tubes; the engine just sort of hangs in there like the Honda Hawk series motorcycles of the mid-60s. If the frame tubes and engine unit are suitably strong, there is no reason to install front tubes at all.

Utilizing large tubes with sufficient triangulation, the Laverda's frame is strong enough to resist flexing from side loads imposed by vigorous cornering as well as those experienced while riding at speed over bumpy roads. Construction detail on the frame is good: welds are smooth, paintwork is smoothly applied and the whole package "looks" right, even though the frame is on the heavy side.

Braking, too, has benefited from Laverda's road racing ventures. Slightly over nine inches in diameter, both brakes feature double leading shoes using two brake arms which pull toward each other, instead of a rod between the arms which requires critical adjustment to work properly. Cool air is admitted to the front brake by a ribbed scoop cast into the brake backing plate, and a fan-type arrangement is employed on the rear wheel. After circulating around inside the brake drums and cooling them and the brake shoes, hot air is expelled through slots in the central portion of the hubs.

A brake swept area figure of 67 sq. in. for a machine weighing over 500 lb. might not sound too impressive, but the brakes are so well designed and executed that they match the machine's performance with no trouble. In fact, the rear brake must be applied with caution during heavy deceleration or it will lock up. This is caused by the tremendous mechanical advantage afforded by the long brake pedal assembly. It's rather like having a power assisted rear brake.

The Ceriani people have the reputation of producing some of the finest suspension units for motorcycles in the world and those fitted to both the front and rear of the 750 SF are no exception. The front forks are slightly stiff, fitting the nature of the machine, but have more than adequate travel and rebound damping characteristics for fast riding. A nice touch is the pair of aluminum alloy triple-clamps and the aluminum alloy steering damper knob. So precise and stable is the steering that we didn't bother using the damper at all. Also slightly stiffly sprung, the rear suspension units have more positive damping than other Ceriani units we've sampled lately and feature a lever almost 3 in. long for rapid adjustment of the three-position springs for heavier loads.

When we pulled into our favorite gas station for a fill up one of the attendants quipped "that's the biggest Honda Super Hawk I ever saw." Very similar in appearance to recent Hondas, the 750 SF engine is a vertical Twin with a twin-row chain driving the overhead camshaft. But many of the similarities between it and the Honda end here. The drive for the tachometer is located at the left hand end of the camshaft, but the contact breaker points aren't to be found on the right hand side of the head like a Honda. And instead of having a 180-deg. crankshaft the Laverda has the crank throws in the same plane so it fires like a British vertical Twin.

Many manufacturers have adopted the practice of splitting the crankcase halves horizontally instead of vertically, which simplifies inspection and rebuilding, and lessens the number of seams where oil might escape. The Laverda's entire oil supply, which is shared by the transmission and primary drive/clutch, is located in the crankcase and is circulated by a double gear pump. After being picked up by the pump the oil is directed to a centrifugal oil filter which spins impurities to the outside of the filter casting. The filter is readily accessible by removing a cover on the left hand side of the engine, and an additional wire mesh screen keeps any large flakes of aluminum or steel from going through the pump.

Four hefty main bearings support the crankshaft. The inner two are rollers and the outer two are ball bearings. With such support, the engine can be spun at high rpm without fear of crankshaft flexing and bearing failures. Strong steel I-section connecting rods ride on double-row roller bearings at the big ends and support the pistons using bronze bushings. Three-ring pistons featuring two compression and an oil scraper ring are used. Compression ratio is 9.65:1.

Getting the engine's power back to the transmission is a problem solved in many ways. The British have traditionally used chains, the Japanese use gears wherever possible. The Laverda follows in the British tradition and uses a triple-row roller chain whose tension is maintained by a spring-loaded roller wheel. A hefty clutch runs in an oil bath and is moderately hard to pull in. However, it takes the strain of drag strip starts without a whimper and is incredibly smooth in operation. A properly adjusted chain is quieter than even a helical cut gear, so the primary drive adds practically no noise to the motor area.

A look at the overall gear ratios will tell the alert reader that this five-speed gearbox would be well suited to production racing. Closely spaced, the gear ratios enable the rider to maintain a good rate of speed while keeping the engine "on the boil" on a twisty road. Shifting can only be described as flawless, or at least after the initial stiffness disappeared. Both mainshaft and layshaft are supported on the ends by ball bearings and the shifting drum is made of aluminum with a steel sheath around it to minimize wear where the shifter forks ride. Gear lever travel is reasonably short considering the length of the lever itself.

Although quite large as a package, the engine/transmission unit is surprisingly delicate in areas where strength is of minor importance and sufficiently robust where needed. Acting like it does as a frame member requires that certain areas be strong and they certainly are. Finish of the engine castings is particularly good with a sandblast finish on the cylinder head, cylinder barrel and central crankcases and highly polished castings for the outer covers. Not so smooth as the Japanese die castings, but a sandblast finish is more effective in dissipating heat than a smooth one.

Many items on the Laverda are of other than Italian manufacture, and not the least of these are the electrics, excluding the horns. Mention should be made of the Fiamm horns which emit a blast loud enough to wake a sleepy tractor-trailer driver from his air-conditioned reverie. Air-powered versions of these "hooters" come as standard equipment on many of Italy's high performance sports cars and not enough good can be said about them. They're the best motorcycle horns we've ever seen.

The battery is also manufactured by Fiamm, but the generator, starter motor and headlight are Bosch units manufactured in Germany. The headlight is identical to the ones fitted to the pre-/5 series BMW machines and features a round key which is inserted to supply current for starting and running. A turn of the key in one direction turns on the taillight and parking light, and a flick in the other direction turns on the headlight. No kickstarter is fitted to the Laverda so it would have to be given the old run-and-bump treatment if the battery went dead. With a hot battery, starting is extremely rapid. Just close the handlebar-mounted choke lever half way, touch the starter button on the right handlebar and the engine bursts to life almost immediately. Even after killing the engine several times on purpose, the battery supplied enough current. to spin the engine effortlessly.

Detailing is above average. A nifty compartment in the rear of the seat can be used to store tools (in addition to a holder under the seat and behind the battery) or small parcels. Aluminum alloy wheel rims are employed in an effort to reduce unsprung weight and beautiful stainless steel fenders with attractive shapes keep road dirt and moisture off the rider. A small handle is welded to the frame on the left hand side to give the rider a place to grab when putting the machine on the center stand.

Chrome plating on the exhaust pipes and mufflers, which has been a weak point on some Italian machines in the past, appears better than average and the mufflers emit a sound that will gladden the heart of the four-stroke enthusiast. Deep and mellow, with just a hint of throatiness, the sound is just beautiful although spirited riding might arouse the local gendarmerie. The balance tube between the two exhaust pipes helps mid and top-end power somewhat and reduces the exhaust noise level a trifle. Other items of German manufacture are the Metzler tires, a rib pattern on the front and a block pattern on the rear.

Surprises keep cropping up, even in front of the handlebars. Although calibrated in kph on our test machine the speedometer, as well as the tachometer, are manufactured in Japan and look suspiciously like they were swiped off a Honda CB 750.

Aside from a thin looking paint job on the gas tank and side covers, the 750 SF is a superbly finished motorcycle, but we feel that most American riders would prefer slightly higher handlebars and a longer seat for toting their lasses around. But then, that's what the 750 GT is all about and it will be available for $60 less than the SF.

Source Cycle World 1972

 

 

 

NOTE: Any correction or more information on these motorcycles will kindly be appreciated, Some country's motorcycle specifications can be different to motorcyclespecs.co.za. Confirm with your motorcycle dealer before ordering any parts or spares. Any objections to articles or photos placed on motorcyclespecs.co.za will be removed upon request.  

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