The Triumph Rocket III has the world's largest production motorcycle engine and is famous for the massive torque it offers. Each cylinder of this engine is larger than that of the engines found in the Ferrari 458 Italia and even the Mercedes-Benz G63 AMG! In more direct terms, every cylinder displaces more than what a typical three or four-cylinder supersports motorcycle does. In this feature we take a look inside this massive powerplant, bringing to you an insight into how this unique engine works.
Superlatives have always had an unmatched charm that draws unfathomable attraction from followers of any particular genre. This theory works remarkably well in the world of motorcycles, especially when talking of numbers such as displacement and output. The Triumph Rocket III rules the kingdom of series-production two-wheelers globally in terms of displacement. Given our penchant to find out how things work inside-out, we asked Triumph for a Rocket III and what followed thereon is here for you to read.
The Rocket III has always been known for being propelled by large, torque-injected engines. In its latest form, which is sold as a CBU in India, the unit is a 2.3 l (2,294 c), three-cylinder, liquid-cooled, DOHC unit. With a bore of 101.6 mm and a 94.3 mm stroke, each cylinder displaces over 764 cc. In line with present and future emission norms, the bike is equipped with multipoint sequential electronic fuel injection. All this though isn't the highlight since that part is taken up by the odd triple-cylinder layout, which Triumph is a master of but we still had a hard time believing if it would really work as claimed.
We found the engine to be super-smooth and responsive, a bit off from our expectations in a positive manner. Also, the engine despite being huge felt visually somewhat compact, slimmer actually for a 2.3 l displacement. Part of the trick lies in the way the cylinders have been arranged – horizontally and along the motorcycle. This not only allows for a slimmer footprint, but also allows for the crankshaft to be aligned with the final shaft drive, further lowering the physical profile.
The advantage of using a shaft over of a chain/ belt drive is that the shaft needs no maintenance beyond the regular service schedule. The theoretical disadvantage is heavier weight and more loss of power from the crank to the wheel, the latter being something we weren't able to verify for the Rocket III in particular. An interesting find though was the bike's tendency to lean towards the left every time the throttle was pulled, when stationary. This is due to the north-south positioning of the crankshaft, which counter-rotates to the drive shaft.
Offsetting the vibrations of the triple-cylinder configuration further is the fact that the engine acts as a stressed member of the chassis. This helps dampen the vibrations to an extent, enhancing the smoothness of the ride.
Coming to power, the output for this engine is rated at about 146 hp and 221 Nm of torque @ 2,750 rpm. Factor in the 367 kg kerb weight, and the torque count is still a lot. Availability of torque in the lower revs is particularly helpful during quick overtaking and negotiating traffic. There is ample torque right uptill about 5,300 rpm, another 500 rpm north of which the engine signs-off, reflecting the short rev band. Shifting a bit under 5,500 rpm is the best way to ensure the tapering of power is negated. The mid-range then, between 2,500 rpm and 5,000 rpm is where the engine shines through in seamless and rapid power delivery.
The electronic engine management system does a great job of balancing out things and the wide spread of torque results in beyond-belief roll-on times. Such is the surge of power that the time lapse between opening the throttle at 100 km/h in top gear and reaching 160 km/h is just about five seconds. A 0-100 km/h dash was done by us in 3.2 s, and 0-160 km/h took just under eight seconds.
That brings us to the five-speed gearbox, which is the only thing in the powertrain that left us wanting. Compared to the earlier model, the present Rocket III has derestricted power in the first three gears, allowing for a quicker acceleration. The unit responds well to quick shifts but isn't as smooth as one would expect on basis of the engine refinement. Finding neutral is not simple and at times it feels as if the rider is tapping his left feet to a melody, while in reality the effort is to get the neutral gear position. The exhaust note is raspy and good to hear but given the bike's character and the engine size, a little more of decibels would've been a worthy addition.
The Rocket III is an unmatched machine, not just because of its massive dimensions but the sheer size and character of its engine. The design is purposeful and mixes muscular lines with mechanical beauty in a nice manner. The twin-headlamps, huge radiator, generous amount of chrome and a massive rear tyre lend the motorcycle a dynamic look.
Riding position is comfortable but the stretched handlebars become an aerodynamic hurdle at high speeds. The upright posture combined with open arms make the rider act as a major obstruction for the air, which can be quite uncomfortable at high speeds. When accelerating from about 100 km/h, an extra bit of caution is recommended as the wind resistance keeps getting stronger.
On the dynamic front, the Rocket III might give an impression of straight-line dominance and nervous in corners. Surprisingly though, the bike is genuinely agile and one can put it through a series of quick turns without losing confidence in the handling. Going through sharp turns though, one does need to muscle the motorcycle a bit. The brakes deserve a special mention here, as they bring the huge mass of the Rocket III in a quick and spectacularly stable manner. The ABS works brilliantly and on our manic roads one can apply the brakes hard without the worry of scraping the tarmac. The stability of the bike under hard braking adds further to the rider confidence. In traffic and on city roads, the motorcycle is manageable and the ride quality is quite comfortable.
At Rs 20.7 lakh, ex-showroom, Delhi, the Rocket III isn't an easy buy, but when one puts into equation the fact that there is no other motorcycle in the world like the Rocket III, the price-tag seems justified. The technology this machine delivers is thoroughly modern and proves that one doesn't need to stick to archaic technology to deliver character. In the end though, the Rocket III is a massively quick machine and deserves proper respect. With that respect in place, the Rocket III is a machine the rider can instantly form a bond with and exploit the vast envelope of performance that the motorcycle offers.
Text: Arpit Mahendra
Photo: Bharat Bhushan Upadhyay