Baby Bonnie: 1966-1973 Triumph 500cc T100R Daytona

Buddy Elmore’s victory in the 1966 Daytona 200 is the stuff of legend. Last-minute fixes to his tuned-to-the-max race bike put him at the back of the grid in 46th place. Regardless, by lap 22 he had fought his way through the field and stayed in the lead to the finish, setting a record speed of 96.58mph.

Elmore’s victory was remarkable in many other ways: his 1966 racer looked surprisingly close to the street 500 except for a new cylinder head with dual Amal GP carburetors, energy transfer ignition, oil cooler, one-gallon oil tank, racing exhaust and strengthened swingarm. Inside the engine, Triumph’s Doug Hele had worked his magic to unlock the engine’s potential, but reliability suffered; and in completing the full 200 miles, Elmore’s bike was more the exception than the rule. (Gary Nixon’s 1967 winning engine was strengthened with a full ball and roller main bearing crankshaft. That year, Elmore finished second.)

Moto marketers have never been shy about naming their machines for successful racing exploits and their locations. Think: Le Mans, Thruxton, Sebring, Monza, Manx, Bonneville, and — of course — Daytona. Winning the “Handlebar Derby” at the famous Florida course was perhaps the most prestigious victory of them all.

So when Triumph racked up three wins in the 1960s with their 500cc Tiger twin, (Don Burnett in ’62, Elmore ’66 and Nixon ’67), it was only a matter of time before the company capitalized on its successes. In late 1966, Triumph announced a new 500cc street sport bike based on the single-carb T100 Tiger but fitted with a new cylinder head featuring shallower valve angles, splayed intake ports to make room for twin Amal Monobloc carburetors, 9:1 compression, and Bonneville cams with larger followers: the T100R Daytona.

The drivetrain fitted in a new chassis with revised steering geometry and a stiffer swingarm mounting, but the rest of the bike was familiar Tiger territory. The 69mm x 65.5mm air-cooled OHV parallel twin’s heritage was easily traceable back to the 1937 Speed Twin, exposed pushrod tubes and all, though the transmission now shared its case with the engine. The new cylinder head topped the same iron cylinder barrels. The alloy rocker covers featured screw plugs providing access to check valve lash. Drive was by duplex primary chain to a 4-speed gearbox with gear position tell-tale. The Daytona ran on 3.25 x 19-inch front and 4:00 x 18-inch rear tires sharing the same 7-inch SLS drum brakes front and rear.

Upgrades for 1970 included a strengthened engine with ball and roller bearing bottom end, E3134 racing cams, revised front fork, and finally a decent front brake, the 8-inch TLS item from the Bonneville.

How did the Daytona compare with its bigger brother? It weighed in at 356 pounds dry, while the Bonnie claimed 387 pounds. Power was given as 39-41hp @ 7,400rpm for the smaller bike, and 46-50hp @ 7,000rpm for the 650. Seat height was 30-inches (31), and wheelbase 53.5-inches (56). This translated into a standing quarter of 14.9 seconds @ 90mph (13.9 @ 96) and a top speed of 105mph (112). The extra weight and power of the Bonnie cost potential buyers around $200 more than the Daytona’s $1199 list in 1969.

Though the Bonneville received the new oil-bearing chassis in 1971, the T100 continued with the lug and braze frame until the last Daytonas left the factory. Likewise, it never adopted the 1971-on TLS front brake, continuing to use the earlier (and superior) TLS brake from 1968. Nor did the Daytona ever get a front disc brake (though some 14 prototypes did escape the factory). Then in 1973 came the factory closure and the workers’ sit-in. Only the 750 Tiger and Bonneville were produced at Meriden after that.

Cycle World tested a Daytona in 1967, calling it “A café racer’s dream.” Cycle was equally gushing: “Nothing but good may be said of the Daytona as day-in, day-out sporting transportation. It is a fantastically comfortable bike — Starting is a snap, for it fires very willingly. Add to all that the obvious quality of materials and care in workmanship and you have a lot to like.”

But six years later the Daytona was looking stale-dated. In a side-by-side comparo with the new Yamaha TX500, Cycle concluded that everything the Daytona does, the 4-valve, electric-start, disc-braked TX “does better — except be a Triumph … and that is the best and as far as we can tell only reason for preferring it.” The last Daytonas were built at Meriden in late 1973. Buddy Elmore was killed in a street crash in 1975 aged just 39, and has yet to be inducted into the AMA Motorcycle Hall of Fame. MC

Contenders: Two more middleweight twins

1965-1974 Honda CB450K/SS

• Years produced: 1965-1974
• Power: 43hp @ 8,000rpm (1968-on, 45hp @ 9,000rpm)
• Top speed: 112mph (claimed)
• Engine: 444cc (70mm x 57.8mm) air-cooled, DOHC parallel twin, 9.0:1 compression
• Transmission: Wet multiplate clutch, 4 (5 1968-on)-speed gearbox, chain final drive
• Weight: 420lb (curb, half tank)
• MPG: 44.7 (period test)
• Price then/now: $957 (1968) $1,399 (1974)/$5,000-$11,000 (1965) $2,000-$5,000 (1974)

By the time Honda’s CB750 became the nail in the British motorcycle industry’s coffin, the Black Bomber had already closed the lid. With performance comparable to Triumph’s Bonneville, the CB450 also boasted double overhead camshafts, a twin leading shoe front brake and electric start. Perhaps even more important; unlike earlier pressed-steel-frame Hondas, the CB450’s tubular chassis looked right. Available only in black when it was first released, the CB450K was built around a short-stroke, 180-degree, 4-main-bearing crankshaft, which drove two overhead camshafts by chain. Valves were closed by torsion bar springs with eccentric adjusters. Drive to the 4-speed gearbox was by wet multiplate clutch with chain final drive.

The drivetrain fitted into a single-tube cradle frame with conventional telescopic fork and dual spring/shocks on the rear swingarm. And the CB450 was continually revised and improved over its production lifetime in technology and aesthetics. For 1969, the new Super Sport K1 got larger valves, revised camshaft timing for an extra 2hp, a 5-speed gearbox and nitrogen-filled de Carbon rear shocks. A disc front brake was fitted for 1970.

Cycle magazine tested a CB450 in November 1968, and while testers found the suspension stiff and the TLS front brake “marginal,” its handling was “on a par with the good middleweights, its toughness on a par all its own. Best of all, the bike feels right — everything tight, snug, rubber-mounted where necessary and working together.” They concluded: “The new Honda is beautifully engineered, clean, stylish, easy to maintain and quick. What more could you want in a motorcycle?”

1970-1973 BMW R50/5

• Years produced: 1969-1973
• Power: 32hp @ 6,400rpm
• Top speed: 97mph (claimed)
• Engine: 498cc (67mm x 70.6mm) air cooled, OHV flat twin, 8.6:1 compression
• Transmission: Dry clutch, 4-speed gearbox, shaft final drive
• Weight: 451lb (curb, full tank, 1970-1971), 440lb (1972-1973)
• MPG: 51 claimed
• Price then/now: $1,025 (est.)/$3,500-$8,000

BMW announced the “Slash 5” series (R50/5, R60/5 and R75/5 of 500, 600 and 750cc) for the 1970 season — and a revolution in BMW motorcycle design. Though the basic flat twin “boxer” layout remained, just about everything else was new. The engine used a forged one-piece crankshaft (previously built-up) with plain-bearing rods (rollers). A duplex chain (gears) drove the camshaft, moved from above the crankshaft to below. Light-alloy cylinders replaced cast iron and were capped with redesigned cylinder heads fed by dual Bing slide carbs (CV on the R75/5). Twelve-volt electrics featured push-button start, though a kickstarter was retained. A single-plate, engine speed clutch drove the 4-speed gearbox, with shaft final drive built into the right-side rear swing arm. The tubular steel frame used duplex tubes with rear spring/shock units adjustable for pre-load with a simple hand lever. A telescopic fork controlled the front. The tires were 3.25 x 19in front and 4.00 x 18in rear tires. Brakes were 200mm drums, TLS front and SLS rear.

Though similar in weight to the BMW R50/2, the /5 gained 6 horsepower, giving it a livelier performance, while the new frame and suspension improved handling. Moving the camshaft below the crank also meant the cylinders sat higher up, improving ground clearance. For 1972, the 4.5-gallon chrome-paneled “toaster” tank replaced the bulky 6.3-gallon item; and during 1973 the swingarm was lengthened by two inches. And while performance may not have been its strong point, the R50/5 developed a reputation for reliability and longevity. The 600 and 750cc engines were carried over to the disc-braked, 5-speed “Slash 6” range in 1974: the R50/5 was quietly dropped.

Originally published in the March/April 2023 issue of Motorcycle Classics.