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| Classic sport bike makes a classy commuter |
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Dave Abrahams April 15 2003 at 06:55AM |
Get IOL on your mobile at m.iol.co.za |
Among the rarest and most unusual Italian bikes is Moto Morini's range of modular V-twins, produced in small numbers from 1972 to 1993 at the family-owned Bologna works. The first to appear was the 3½ (350cc), which was designed by Franco Lambertini and first shown at the Milan show in November 1971.
Lambertini's magnificent 72Ί V-twin is based on proven, conservative engineering principles, applied in unconventional ways. For instance, its a pushrod motor but with a high-mounted camshaft set in the vee and very short pushrods, driven by a toothed rubber cambelt, almost unheard of in 1971. The cylinder heads are flat, the valves are parallel and the combustion chambers are recessed into the top of the pistons. It's called a Heron head and, if it sounds familiar, it's exactly the same as on a 1600cc Ford Kent engine. It also allows impressive compression ratios on ordinary petrol the 500 runs at 10:1, high for the period. It's fed by two very ordinary 28mm Dell'Orto carbs mounted back-to-back in the vee and drives via a (theoretically) dry clutch and a five-speed gearbox. In typical late-1960s European fashion, the gearshift is on the right and the kickstart on the left. An electric start is fitted, though that on the test bike wasn't working.
This idiosyncratic motor kicks out 31.3kW at 7500rpm with usable power from 2500 revs. It vibrates noticeably until just over four, at which point it comes on song, smoothing out and surging strongly forward. Morini's contemporary factory literature claims a top speed of 175km/h and the Sport went easily up to 163 in performance testing, the little vee spinning at 6500rpm with no sign of distress, accompanied by a harsh and flat barking from the replica factory tailpipes (no noise regulations in 1975, Cyril). The clutch is firm and predictable, with a sudden take-up very close to the grip, typical of multi-plate dry clutches. The test bike's clutch exhibited some clutch drag when hot, due to a faulty seal having leaked some oil on to the friction plates, but that's easily fixed with some solvent and steel wool to remove the glazing. As it was, it just meant I had to be careful to find neutral before the bike stopped moving, not always as simple as it sounds because there's no neutral light. The gear lever extends from behind the foot-peg and its action is a little long but light and firmly positive. After a little practice I was able to reel off seamless upshifts without the clutch, although I always used it for downshifts out of respect to the box's age. conventional frame This beautifully sculpted and surprisingly narrow motor is mounted in a neat, conventional double-cradle frame welded from steel tubes with 35mm Marzocchi cartridge forks in front and twin hydraulic shock absorbers, adjustable only for preload, on the swing-arm. The wheels are crisp cast alloy and the brakes are by Grimeca, twin 260mm discs in front and a single rotor the same size on the back wheel, all with opposed-piston calipers. This was cutting-edge stuff in the mid-1970s. The rest of the bike is all borrowed: the switchgear and all the lights are from Ducati's 860GT, the instruments from the Guzzi V50 and the fuel cap is shared with every Laverda and Ducati of the period. It has all proved durable and reliable and everything falls neatly to hand, which is more than can be said for some modern machinery. Weird features abound; the bike has a unique electronic fuel tap on the left side of the tank which opens with an audible click when you switch on the ignition but the right (front) carburettor is fed by a normal three-position manual tap just like any other bike of the period. The motor has four breathers, all in a collector box behind the motor. To keep the bike from dribbling all over itself, the twin overflow pipes are now led into a 500ml bottle hidden behind the battery. In two weeks it collected about a tablespoonful of oil. Despite an odd riding position, with the footpegs rather too far forward for the low, narrow clip-ons, the long, deeply padded seat is remarkably comfortable with plenty of room to move around on longer rides. Superb road-holding The bike is a joyOn the road. The frame is taut and more than stiff enough to cope with 31kW and a dry weight of just 160kg. The steering is razor-sharp and as quick as a modern GP machine while the low centre of gravity and amazingly narrow chassis allow the bike to be flicked from side to side like a kitten chasing the wind. On smooth roads the road-holding is superb even by modern standards, the ground clearance more than adequate and suspension surprisingly supple. The only time the damping shows its vintage is on bumpy back roads, where it begins to patter when pushed. The brakes take a firm squeeze to get them working but then haul the bike down firmly and controllably although the back brake is if anything a little too powerful; I locked the rear wheel a couple of times at low speeds. In heavy traffic the motor's quick response and mid-range torque let you grab the narrowest of gaps and, unusually for an outright sports bike of any era, it will sit at a red light for as long as you like, quietly idling at an even 1000rpm. Within its limits, Morini's middleweight vee is a magnificently competent package. On a twisty but well-surfaced road it's pure sex on wheels, yet it will idle reliably and has the tightest turning circle I've yet measured on an Italian bike. It's as good a commuter as anything you can buy off the showroom floor, with a healthy dose of vintage class. It's also widely regarded as the prettiest motorcycle yetbuilt; certainly that air-cooled 72Ί V-twin is the most exquisitely sculpted engine in motorcycling. Allam and Piller were right; it's a very nice street bike. I didn't want to give it back so thanks for the loan, gentlemen. Specifications Motor: Air-cooled four-stroke V-twin. Capacity: 478cc. Bore x stroke: 69 x 64mm. Valvegear: Pushrod with two overhead valves per cylinder. Compression ratio: 10.0:1. Power: 31.3kW @ 7500rpm. Induction: Twin 28mm Dell'Orto PHBH slide carburettors. Ignition: Electronic. Starting: Electric and foot. Clutch: Cable-operated multi-plate dry clutch. Transmission: Five-speed gearbox with chain final drive. Suspension: 35mm conventional cartridge forks at front, twin hydraulic shock absorbers adjustable for preload at rear. Brakes: Twin 260mm discs with Grimeca twin-pot opposed piston callipers at front, 260mm disc with Grimeca twin-pot opposed piston calliper at rear. Tyres: Front: 100/90 H18 tube type. Rear: 110/90 - H18 tube type. Wheelbase: 1460mm. Seat height: 780 mm. Dry weight: 160kg.
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