Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/128331
I_~'---;;:-Tn;-'um :-oc'ke-:-t-;-; -11/-plh-;:;R - - - -- - -- - - - T - - - - - riumph's effrontery in conce iving t he largest-capacity vol um e-production moto rcycle ever to r each the streets in modern times , the 2]00cc Rocket III, was a courageous roll of the dice that seems certain to payoff. Extending the company's trademark t hree-cylinder engine for mat to the cruiser category was already a brave move - rather than concocting yet a nother pseudoHarley V-twi n or even, as was at one stage e nvisaged, a Valkyrie-rivaling V6 - and to do so by creating a motorcycle w ith a bigger engine than most cars to be found on the roads o f Europe was astonishing. But to endow the result w ith a level of perfo rm ance tha t any 1000cc Superbike will struggle to kee p up with in real -world condit ions up to license-losing speeds was comic-book stu ff turned into rea lity, confirmed - says Triump h - in side-by-side tests w ith some une xpected rivals. Triump h's Incredible (lite ra lly!) Hulk will out-accelerate a Hayabusa off t he mar k, powering from 0 to 60 mph in less than 2.8 seconds - faster than a Yamaha RI and, pe rhaps more importantly in the eyes of its ta rge t custom e r, twice as fast as a Ho nda VTX 1800. It produces more to rqu e at idle Technical: Bigger is The badges on the sidecovers beneath the seat of the new Triumph megacruiser say it all: "Rocket III 2]oocc." That makes the new bike the world's larges t-displace ment production motorcycle, with a very modem, very original - nobody ever did anything like this before! all-aluminum 101 .6 x 94.]mm liquid-cooled three-cylinder in-line 12-valve engine, mounted longitudinallyin the frame and measuring 2294cc - or a crucial 140 cubic inches in American rather than metric terminology, a nice, round number that says "Beat that !" to Triumph's 8.7: I compression. The 12-valve cylinder head has double overhead camshafts chain-driven up the front of the engine, with paired ]7.9mm inlet and 32.]mm exhaust valves and dual ignition employed for showroom rivals for the customer dollar. the first time on any That means the Rocket III bike engine rep resents exactly one-half of a current Chevrolet V6 car motor, and it has a larger capacity than the power units of 70 percent of the fourwheeled products manufactured last year by the European automotive industry, with an out put of 140 bhp at 5750 rpm and a humungous 147 ft.-Ibs. oftorque at just 2500 rpm - of which 90 percent is already on tap at just 1800 rpm . In order to achieve a low center of gravity for what by motorcycle standards is such a massive powerplant, weighing a hefty 275 pounds - includingthe five-speed gearbox offset to the left ofthe crank and fitted with stacked shafts RI-style, so as to reduce the overall width of the motor - the liquid-cooled Rocket III engine is a dry sump design, with the lozengeshaped five-liter oil tank emblazoned with the slogan "Fue l Injection" mounted halfwaydown the left side of the motor, beneath the intakes for the three 52mm Keihindual-butterfly single-injector throttle bodies. The lack of a conventional wet sump has the effect of making the vertical-block Rocket Ill's center of gravity even lower than Honda 's flat-six F6C Valkyrie, with the crank mounted just 205mm above the ground . To the rider sitting in the seat , the engine turns in a clockwise direction from left to right, with the ]8.9-pound forged crankshaft featur ing even, 120-degree throws so heavy that a special production line had to be installed in the Triumph factory at Hinckleyto build the motor, equipped with a crane to lifteach crank into place on the assembly line. In order to remove Triumph model to take vibration as well as minimize torque react ion from the lengthways engine, there's a substantial balance shaft alongside the crank, which rotates in the oppos ite direction to it, as does the transmission. Result: Youcan balance a flat-edged heptagonal British 50p coin on the fuel tank with the engine running at its 500 rpm idle speed, without it falling over. That 's smoot h. Though employing the same 10 1.6mm bore as the V I0 Dodge Viper sports car (and so, by definition, the outrageous but improbable Tomahawk project bike using the same e ngine), the Rocket Ill's three-ring pistons are actually a little smaller than the V-twin Kawasaki's VN2000's I03mm slugs, sitting on forged conrods running on the plain-bearing crank and delivering An II11V7 ?()()A • r.Vr.,r: N~WS account of the large bore size in maximizing combustion and enhancing emissions control. Aside from the long IO,OOO-mile service intervals, representing an expression of Triumph's confidence in the reliabilityof such an innovative if com paratively low-stressed engine, the Rocket III is also surprisingly frugal, delivering 42 mpg in spirited use and thus a range in excess of 200 miles from the 6.5-gallon fuel tank . This comes via the combustion efficiency of the twin-plug cylinders, as well as the optimized mixture flow and fuel mapping obtained via the Keihin EFI and the twin butterflies in each throttle body (same as in the Daytona 600), one of which is operated normally by the light-action twistgrip, the other by the ECU according to gear selected, engine load and road speed. This also provides for the engine 's massive torque to be restricted in the lower gears via the mapping of the engine management system, as is commonplace today with high-performance car engines in order to avoid placing too great a load on the transmission, and especially the drive shafts. Though that was surely a consideration on the Rocket III, too, Triumph says the main rea son for backing off the torq ue output by 7 percent in the bottom two gears was to deliver a more progressive power delivery so that riders stepping up to the 140 cubic-inch megacruiser from a less powerful motorcycle - like a Harley, say, or a Honda? - wou ldn't fee l daunted by the explosive pickup of the original prototype! Doe s that make it more user-friendly now cuddly, even? Well, let's just say test riders aboard the first Rocket III prototype spoke of "aweso me torque" and "absolutely massive power," persuading Triumph management that it could (should?) soften the de livery a little, without compromising the Rocket Ill's ability to produce the most from the biggest, the strongest from the best. This is in every way a bike 40th Anniversaru