Mv Four Cylinder

MV FOUR CYLINDER

CARLO PERELLI

IT’S HERE! The most fabulous roadster ever produced, the 600 MV four, is now on delivery at $1860.00 in Italy, and we’ve been lucky to have one for a day. Fantas-tic! Anxious to read about the riding im-pressions? Wait a minute, mates, take a few technical facts and figures first. They are like appetizers and will help you better understand this unique machine.

Derived from the ultra-successful 350 and 500 racing jobs used by Surtees, Hailwood and Agostini, the engine has been increased to 600cc and fitted with electric starter and shaft drive, not only for more luxury, but also to avoid custom (private) racing conversions, believed to have caused troubles and adverse publicity for the factory. In fact, Count Domenico Agusta, who initiated the project some two years ago, has been very keen on its development, and wants this mount to be the “supreme luxury” but with absolutely no racing attributes. As a matter of fact, there is no particular accent on acceleration (100 mph from standing in 24 seconds) nor on top speed (about 110 mph). But we already know of some people who are studying how to improve both, as well as to “underbore” it to 500 to have a go at racing!

The light alloy cylinders, with austenitic barrels, are separate and inclined at 20 degrees; the heads, on the contrary, are united two and two: of course, in light alloy, have 40 degree inclined valves, with helical springs and a diameter of 30mm inlet and 28.6mm exhaust (1.8” and 1.25” respectively). Bore and stroke are 58x56x4 — 572cc, compression ratio is 9.3—which makes 100 octane fuel compulsory—and power output 50 bhp at 8,200 rpm.

If you judge the price of the bike a trifle too high, just think that the crankshaft alone costs $480.00 , because of the built-up (composite) construction, enabling one-piece con rods with big ends on caged rollers. The crank runs on four inner and two outside main bearings and has a central gear to drive the double overhead cam, the ignition distributor (placed vertically behind the cylinders) and the oil pump, plus another gear—between the first and the second cylinder on the left—for the primary drive. The multi-disc clutch is also on the left.

The crankshaft chamber is split horizontally to facilitate mounting of the crankshaft; the crankcase, on the contrary, is in one piece, including the finned oil sump, with side covers and the 135W-12V generator-cum-starter placed at the rear of it, under the swinging-arm spindle. The rubber belt taking the drive to the engine is somewhat exposed.

Mixture is fed through two 24mm diameter carburetors, with a car-type “compensator” (no other details given by MV technicians) in the manifold for low and regular idling—which is really good, at 1,000 rpm—as well as right mixture in all four cylinders at every engine speed.

The primary drive ratio is 1.75:1; the five internal gearbox ratios are 3.57, 2.43, 1.68, 1.241; the bevel gear ratio is 1.06:1 in the crankcase and 3:1 at the rear wheel. Final drive ratios are 20, 13.6, 9.43, 6.96 and 5.6. The 18-inch light alloy rims are fitted with Metzler 3.50 (front) and 4.00 (rear) tires; diameter of the two front disc brakes is 216mm (8.5 inches), while the orthodox full width rear drum brake has the useful dimensions of 200x45mm (8.0x1.2 inches). Weight is 485 pounds, and main dimensions are: wheelbase, 55 inches; seat height, 31.5 inches; footrests height, 13 inches; ground clearance, 6.7 inches. Top speeds in the various gears are 30, 45, 65, 88, 110 mph.

And now, before rushing to the machine anxious to go, a few seconds more to have a look at it. A beauty, indeed, with dramatic impressions of power and fine engineering, plus luxury—this latter also due to the black painting, with the tank chromed at the sides. The big, square headlamp, the “meager” front brake, the too-evident hump on the huge five gallon tank, the old style tool-boxes at the sides of the rear mudguard may not please, but are very typical, indeed, as are the crash bars, the long, cylindrical silencers and the “double deck” dual seat.

Finally, let’s open the throttle! The feeling of the turbine-like, vibrations—less four-cylinder engine “crescendo” is wonderful and breathtaking, especially from 6,000 to 8,200 rpm—the limit indicated by the factory, but easily and safely surpassable in lower gears. The works testers often push the engine up to 9,000, but, of course, this is not to be taken as a rule!

Carburetion and pickup are both clean, with only a little spot of bother from 5,500 to 6,000 rpm, which is quickly over if the throttle is opened with decision. Also, after going at slow revs for some time, as it happens in town, for example, a couple of vigorous throttle openings in neutral are needed to clean the plugs again.

Exhaust noise is full and pleasant while the noticeable mechanical noise is practically unavoidable, in spite of extreme care during machining and assembling, because of the many straight teeth gears.

Acceleration is very brisk up to 100 mph. Then it flattens up a bit, and to reach the top speed of about 110 mph it is necessary to crouch on the tank, which is by no means easy and comfortable! As already pointed out, this is not a “speed” machine but a luxury tourer.

The riding position is good, with the body only slightly inclined to counteract wind pressure, but the wide fuel tank forces the legs open a bit too much, while the rubber side pads are not at the right place. Seat height is such that practically everybody can firmly put both feet to the ground. Comfort is, of course, first class.

From the very beginning, the machine offers plenty of confidence and safety at any speed; stability and road holding are good also, because, even with shaft drive, this bike has the engine turning over longitudinally and so has no torque reaction. Owing to the crankcase width, the footrests are rather apart, but they are not uncomfortable for the rider, and above all, being some 13 inches from the pavement, they are not grounding even during brisk cornering. In such occasions it is the side stand which scratches a bit (on the left).

Manual controls are quite good, including the useful handle on the left to facilitate lifting and lowering the machine from the center stand. The ignition key, which switches on the lights, is on the headlamp behind the rev counter (at left) and the speedometer, while the pushbutton making the engine start (without any noise from engaging mechanisms) is easy to reach with the right thumb, near the throttle. Foot controls, on the contrary, are not so good, because you must move the feet to operate both the rear brake pedal and the gearchange rocker type lever, which has medium length “travel” to engage the various gears. Gearbox mechanisms, anyway, work very well—always positive, silent and regularly operating even without the clutch, like on the racing jobs. Neutral is easy to select from standing. Bottom is a bit “short”, but the other four ratios are close, adding pleasure to riding and improving acceleration. Moreover, bottom on such a machine is not often used and, if you wish, it is also possible to start in second. The clutch is surprisingly light to operate and takes up the drive very smoothly.

On our test machine, the front brake was not yet bedded down completely and so made no impressive performances; frankly, also for appearance, we would prefer a nice full-width drum with four leading shoes, such as a Fontana. The rear one, instead, was well up to the needs.