MV Agusta 600GT
Asmooth rustling whistle, ihe quick tearing of thick silk, announces arrival of Count Domcnico Agusta's 600-cc Four. This fascinating sound, an exciting whisper-pitched portent of power, comes as a surprise to those who recall the thunderous MV Agusta machines of the Grand Prix circuit, the championship roadburncrs of Hailwood. Agostini and Surtccs. The good Count's racing Super/Fours arc the brutish forebears of the 60O's powcrplant. but in this machine the excessively peaky performance of the competition motorcycles has been replaced by broader, mid-range rpm flexibility that makes this MV perhaps the premier roadster of the world. This statement is bold, indeed, but it is not made without careful consideration — and a great deal of very pleasurable riding. The bulk of the MV Four is functional. What needs to be big is big. Once rolling, the last trace of massive demeanor disappears completely. If the engine is to be faulted in any respect, it is for lack of flywheel effect. Test riders were forced to maintain an inordinate idle rpm when stopped for traffic lights. Even lacking marked flywheel action, however, the Four delivers adequate getaway power without undue clutch slippage or overly high rpm. Technically sneaking, the powcrpJant is of double overhead camshaft design. The intake and exhaust camshafts both are driven through a gear tower located between No. 2 and No. 3 cylinders of the Four. This particular engine layout is best known for minimization of reciprocating valve train inertia, and for free breathing, as pushrods do not protrude into the intake or exhaust gas streams. Thus, the MV engine's designers weren't forced into parsimony for intake and exhaust port area. The ohc layout, with its straight-cut drive gears, numerous bearings, and lobe-to-stcm cam contact areas, contributes that which is perhaps the MV's outstanding characteristic — the beautiful sound. The valve equipment's audibility is directly attributable to the quietness of the remainder of the MVs power train. The primary gear drive (oil pump and distributor drives, too) also is between the middle cylinders. The constant mesh five-speed transmission delivers power, through the multiple-disc clutch, to a geared, slip-splined cardan shaft which turns the pinion gear, which turns the final drive ring gear. The drive shaft housing is employed as the right-hand swinging arm. The MV's shaft drive system showed no slack, or general jerky looseness, nor the characteristic sounds of chain drive motorcycles. Indeed. The test machine's induction system was not fitted with any sort of air filtration device. Rather, conical velocity pipes adorned the carburetor inlet orifices. Lack of filtered air may be well and good in a region where streets and highways arc regularly washed with rain, but filtration seems mandatory in areas where abrasive dust is an ever-present fact of life — in the western U. S.. for example. Ample spuce is available under the MV's fuel tank or split level saddle for an air filler cannister. The Count's designers could well busy themselves in readying such a device for export models of the MV Agusta 600 Four. True, restriction of intake air would reduce power output of the Four. But what is I bhp of 50 when a magnificent and expensive Italian engine can be prevented from grinding itself to usclcssncss with ingested grit? Frustrated is a less than adequate word to describe the feelings of those who were forced to bump-start the hefty tourer so carefully designed and equipped for effortless electrical pushbutton starting. A U. S.-made light aircraft battery would prove a replacement of adequate power output and suitable size. The MV's 12-V. I35-W generator (which doubles as starter) proved adequate to meet demands of the 45-W The roadable motorcycle, the machine thai is to be driven at lop legal speeds wherever it goes, musi be equipped with mean* to decelerate at the rider's chosen A full stop simply is greater lever pressure exerted more quickly — wilh care headlamp and the 25-W power requirement of tail and brake lights. The headlamp — the shape of which is prohibited in some unenlightened states among the 50 — provided a broad swath of brilliant illumination for nighttime operations. The roadable motorcycle, the machine thai is to be driven at lop legal speeds wherever it goes, musi be equipped with mean* to decelerate at the rider's chosen Source Cycle World 1968
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