MV Augusta Tre Cilindri
Even today, the Italian triple is still revered as the benchmark bike of the classic era of 500cc four-stroke GP racing
When the Grand Prix Hall of Fame is expanded to include machines, as well as the men who rode them, there’ll be many contenders for the title of Race Bike of the Century. But few will possess such strong credentials for that honour as the MV Agusta tre cilindri, which was responsible for Giacomo Agostini winning 13 of his 15 World titles between 1966 and 1973, in both 350cc and 500cc guise.
A key element in the success enjoyed by the triple-cylinder MV during its decade at the top of Grand Prix racing’s technological tree was its light 128kg dry weight, with its 12-valve dohc engine scaling just 55kg thanks to its sandcast magnesium one-piece crankcase. The prominent nose of the typically Italian heavily-finned longitudinal three-litre oil reservoir protrudes beneath it – in fact, its extensive oil system with separate pumps for both the engine and the unit-construction seven-speed gearbox, with its gear primary drive and dry clutch on the left side, means the MV triple motor is both air and oil-cooled.
This doubtless provided inspiration for the first Suzuki
Finned longitudinal three-litre oil reservoir protrudes under engine
GSX-R750 in 1975, which also aesthetically copied the reduced finning of the MV’S one-piece cylinder block, whose in-line cylinders are canted 10° forward from vertical. The train of gears running at half engine speed off the 120° crank to drive the double overhead camshafts, are located on the right side of the engine, inboard of the points for the coil ignition (no MV-3 ever raced with electronic ignition) and surmounted by a curious tower which looks like it contains a bevel shaft, but houses a shimming mechanism to take up the clearance on the cam drive geartrain.
The one-piece aluminium cylinder head houses a trio of bronze inserts containing the combustion chamber for each cylinder, with four valve guides surrounding a single central spark plug. The four valves in each cylinder sit at a total included angle of 73° to each other, with (on the bike pictured here) a set of three 37mm Dell’orto E154 carbs feeding the short intake stubs – 35mm sizes were also used, depending on the circuit. Two-ring Borgo forged pistons are used here as on all the triples, reducing friction without experiencing corresponding blow-by oil problems. Equally avantgarde was the extractable cassette-type seven-speed gearbox, a format MV had already used back in the 1950s on their 125s and 250s, and now considered de rigueur on modern Superbike and GP racers. Back in the 1966/67 seasons, a choice between five different gearsets on the MV-3 gave Agostini a big advantage over Hailwood’s faster Hondas in having the right set of internal gear ratios for each circuit. The three-cylinder MV engine measured 62mm x 55mm in this, its ultimate 498cc guise, with a compression ratio of 11:1, and in this form delivered 78bhp at 12,000rpm at the gearbox. That was a great deal more than the best Manx Norton, with around 50 bhp, or the 58bhp at the rear wheel of a two-valve-per-cylinder Paton twin – plus the MV Agusta tre cilindri was a very reliable machine.
That robustness extended to the double-cradle tubular steel frame, which, since Ago very rarely crashed, tended to enjoy a long life back in the day. This represented a Latin version of the Norton Featherbed, but with detachable lower chassis rails to allow quick removal of the engine. The fabricated box-section swingarm had eccentric pivot adjustment, while at 1310mm, the wheelbase is toy-like – later 125GP Honda two-stroke singles were longer!
This ultimate version of the MV Agusta 500 tre cilindri delivered its unique concert of road racing music via a trio of long, slowly tapering megaphone exhausts – two on the left, one on the right, to give more space for the period right-side race-pattern gearshift lever’s action.
‘THE ONE-PIECE ALUMINIUM CYLINDER HEAD HOUSES A TRIO OF BRONZE INSERTS CONTAINING THE COMBUSTION CHAMBER FOR EACH CYLINDER’