BSA Rocket 3

Rocket 3 / Trident

T160 Triumph Trident
Manufacturer	BSA/Triumph
Parent company	Triumph Engineering
Production	1968–1975
Predecessor	none
Successor	none
Engine	air-cooled 740 cc OHV transverse triple
Power	58 bhp (43 kW) @ 7,500 rpm
Transmission	chain
Brakes	1968–1971: 2LS drum/drum 1972–1975: disc/drum 1975: disc/disk T160
Weight	468 lb (212 kg) (dry)
Fuel consumption	30–40 mpg

The BSA Rocket 3/Triumph Trident was the last major motorcycle developed by Triumph Engineering at Meriden, West Midlands. It was a 750 cc air-cooled unit construction pushrod triple with four gears and a conventional chassis and suspension. The motorcycle was badge-engineered to be sold under both the Triumph and BSA marques. The Rocket 3/Trident was part of Triumph's plan to extend the model range beyond their 650 cc parallel twins. Created to meet the demands of the US market, the smooth 750 cc three-cylinder engine had less vibration than the existing 360° twins. Although BSA experienced serious financial difficulties, 27,480 Rocket 3/Tridents were produced during its seven-year history.

Although the Trident engine was developed in 1962 by Bert Hopwood and Doug Hele, this three-cylinder design was derived from Edward Turner's 1937 parallel twins, the 500 cc Triumph Speed Twin and its sportier sibling, the Tiger 100; but the Trident has an extra cylinder and a longer stroke than the Tiger 100 engine. Following Triumph practice, the OHV pushrod triple has separate camshafts for the inlet and exhaust valves.

Unlike the later Honda CB750 and other Japanese superbikes which had horizontally split crankcases, the Trident engine was essentially a vertically split parallel twin with a separate central chamber to accommodate the third cylinder. Whereas the Speed Twin was a traditional British twin with a 360° crankshaft, this new triple had crankpins offset 120° and so inherently had much smoother primary balance, albeit with a rocking couple. Although most British motorcycles used a wet multiplate clutch, this triple had a dry single-plate clutch in a housing between the primary chaincase and the gearbox. Mounted on the end of the gearbox mainshaft (where the clutch would be expected) was a large transmission shock-absorber.