LOCK STOCK RACER – EXCLUSIVE
Royal Enfield revealed a custom race bike at the recent Bike Shed show in London. Four days later, we’re the first people to ride it…
Behind the scenes and under the skin of RE’S radical new drag racer – and we’ve ridden it
This October, Royal Enfield are expected to start delivering their new 650cc twins. Powered by an all-new engine, the Interceptor and Continental GT (see page 14) are the first twin-cylinder models since production of the original Interceptor ended when the Redditch based factory closed in 1970. First seen at the Milan show last November, the 47bhp twin-cylinder engine is a blend of tradition and modern engineering, with air cooling and a central camchain mixed with a forged 270˚ crank, balance shaft and four-valve heads. By limiting its capacity to 648cc, Royal Enfield’s CEO Siddhartha Lal has astutely targeted a potentially sizeable market segment. There’s
presently no competition in the traditionally-styled retro sector, Triumph declining to move the Bonneville any lower than the 900cc T100 and Street Twin. With Enfield already so firmly established in the middleweight market, creating a 650 makes perfect sense. Except the radical bike here isn’t a 650 any more. This is the Lock Stock racer; it’s 865cc and makes over twice the power of the stock bike, as well as more than double the torque. Oh, and it has nitrous injection... Alongside establishing its new Bruntingthorpe R&D Centre (see page 18), Royal Enfield are developing their own custom programme run in the UK by its group manager for industrial design, Adrian Sellers. Originally focused on aesthetics for the single-cylinder Bullet and Classic, the imminent debut of the 650 means Sellers and his team have started working on delivering extra oomph from the pre-production parallel twin motor, in what also amounts to a bit of ‘what if’ R&D work. And it’s in collaboration with noted US tuning house S&S. Starting with the stock 648cc motor delivering 47bhp at the crank at 7100rpm and 38 lb.ft of torque at 4000rpm, S&S have bored out and presumably also stroked the engine to measure 865cc (hello, Triumph!) without any modification to the crankcases or cylinders. Exact dimensions are secret, though. “Our engineers measured the standard engine,” says S&S’S international sales manager, Martin Szlagowski. “We then worked out where we wanted to go with the bore size available, conrod length, piston weight and so on, in order to maintain a standard-looking engine that doesn’t detract from what the engineering staff at Enfield have done – but which goes a lot faster.” Changes include a high-performance camshaft, plus forged conrods carried by the stock but stroked forged crank, with high-compression forged pistons giving a much higher 12.4:1 compression ratio. There’s a ported cylinder head, and the multi-point sequential fuel injection features S&S’S own ECU matched to larger 38mm throttle bodies, with a high-flow injector kit and manifolds. The racing exhaust system features slash-cut custom headers and no silencing. Pinions in the six-speed gearbox have been undercut, there’s a highperformance clutch, and a Translogic Intellishift quickshifter is controlled by buttons mounted on the left handlebar. Then there’s the Nitrous Express N²O System which kicks in at 4000rpm. Redline is 8500rpm. They’re a little vague when it comes to power, but there’s “over 100bhp” at the rear wheel at 7040rpm with Stage 1 nitrous. They’re quite specific about the torque, though: 83.8 lb.ft at 5840rpm. Way more than double that of the standard engine... To house this radically uprated yet standard looking engine in a drag racing frame, Sellers naturally called on the services of Harris Performance. The glorious racing history of the wholly-owned Royal Enfield subsidiary needs no introduction, but they’d never worked on a drag racer before. “After we got the design ethos from Adrian, we sat down and thought, ‘OK, we’ve not done this sort of thing previously – which is nice!’,” admits Harris project leader Tim Allan. “Our number one aim was to make sure the bike was stable at high speed, and safe. But we also tried to keep it looking like the new 650 road models, so didn’t move too far away from the overall chassis design, even though there’s a hardtail rear that’s extended back for traction off the line, as well as stability. It’s eight inches (203mm) longer, and we can alter wheelbase forward and back by up to 150mm, depending on how we adjust the rear axle blocks. Originally, it was going to be built for an eighth-mile sprint event, but it’s expanded from there, really – it’s got a little carried away with itself, and now we’re looking at going to Bonneville. We’d modify the steering geometry in building a new frame for that – but what we’ve learnt from this bike will help the next-generation chassis.” Presumably Harris have drawn on S&S’S lengthy experience in racing on the Salt Flats; its chief designer Jeff Bailey holds several records for bikes up to 3000cc. “For the drag bike, we discovered that almost a 60/40%
front weight bias is best, but we know from chatting to the guys at S&S that for Bonneville they’re looking for more of a naturally balanced, almost 50/50 weight distribution. Obviously, we’re allowing for that in the design of the Bonneville bike, where the run is that much longer; we’ll be guided by S&S on weight distribution and the headstock, though obviously fork heights, yoke offset and such will change.” The Lock Stock drag racer’s Harris frame is a brazed steel duplex cradle, made from cold-drawn tube rather than chrome-moly and left unpainted to show off the workmanship. Wheelbase is 62in (1570mm) with a hardtail rear end. The 50mm Öhlins RT upside-down fork has been severely shortened for aerodynamic reasons, and so has just 60mm of wheel travel compared to 130mm normally. Braking is by a single 320mm Brembo disc with four-piston HPK radial caliper up front, and a 220mm rear with Goldline two-pot caliper at the back. Forged 17-inch PVM aluminium wheels carry Shinko Stealth tyres. Pete Wycherley made the carbon-fibre bodywork, though RE are reluctant to disclose the weight of the bike. The aptly-titled Royal Enfield Lock Stock (as in the movie, ...And Two Smoking Barrels) was unveiled at London’s influential Bike Shed Show the last weekend in May. The following Tuesday, I’m at Royal Enfield’s tech centre at Bruntingthorpe in Leicestershire for the chance to ride it on the proving ground outside – making it the first time anyone outside the company has actually ridden one of the new 650 twins. What Royal Enfield and S&S have extracted from the new twin-cylinder motor feels pretty close on overall performance to a 984cc Triumph Thruxton I once straight-lined to set a 152mph class record. In fact, the Lock Stock motor has more torque, so feels better off the line. Impressive. It tails off a little if I keep on the gas down the runway, past the end of the theoretical drag strip. However, shifting up through the gears with the push-button powershifter and throttle wide open is slick. Better still, clicking the next gear without using the powershifter or the heavy race clutch delivers crisp, seamless changes from Royal Enfield’s six-speed gearbox, with the glorious boom from the open exhaust altering just an octave or two. At no stage is there any significant vibration from the motor – the counter-balance shaft does its job ideally, in spite of the theoretical increase in vibes from the bored and stroked motor’s extra reciprocating weight. Then there’s the nitrous, which kicks in just on 4000rpm for another rush of acceleration. The tacho needle races towards the rev limiter, and you’re frequently instructed by a bright shifter light. On seeing the Lock Stock for the first time in RE’S workshop, I was uncertain how well I’d fit – but it turns out to be snug and reasonably aerodynamic for a 5ft 10in rider. What the bike can’t do is go around corners, of course, grinding away carbon-fibre from either side if I lean over more than about 15º from upright. It’s a drag racer, after all. For the sprint course at Wheels and Waves, Sellers plans to raise the bike by 45mm at the front to help negotiate the bend at the top of the hill. Though the Harris race chassis obviously has nothing to do with the production bikes, I’m able to get a rough impression of how the Interceptor and Continental GT are likely to be to ride in the coming autumn. What Royal Enfield have produced here is a fine example, in development terms, of having your cake and eating it. They’ve produced a 650 twin that has essentially no rivals in its chosen category – yet while using the same major engine components they’ve also developed a serious contestant in the next category up. Talk about a double whammy... And, with S&S being involved, does it mean we’ll eventually see a Royal Enfield performance parts catalogue for tuning their singles and twins? “The management teams from both companies have been in discussion about where we can go,” says Martin Szlagowski. “We have a performance pedigree, Royal Enfield want to expand their offerings to dealers and consumers, so there’s a good possibility – but that’s down to senior management.” I shouldn’t be surprised that RE’S new parallel twin is such a delightful engine to ride in tuned, uprated guise – especially given the calibre of those who created it, headed by the company’s head of development, Simon Warburton, who formerly did that job at Triumph. The new Royal Enfield 650s are likely to present serious competition for Triumph’s Thai-built Bonnies. And that includes at Bonneville itself, where I have an uncanny feeling that records will be broken by the Indian-made bike designed and developed here in the UK.
“THE NITROUS OXIDE RUSH KICKS IN AT 4000RPM”