Kawasaki Z1 Engine Strip

Transcript

Classic Bike CB1100R BUYER’S GUIDE Raced by Haslam, great for pottering SORT YOUR VELOCETTE Crank, clutch and valvespring solutions SUZUKI RG500 RESTORATION From box of bits to 140mph rocketship MARCH 2013 | DUCATI 750 SPORT & BMW R90S | JOHN SURTEES ON VINCENTS | SUZUKI GT750 ENGINE STRIP | THE BEST ENFIELD? RIDING THE 1953 ISDT WINNER | FREDDIE SPENCER ON HONDA’S 1980 S SUPERBIKES | ISSUE #398 4?? BIKES FOR SALE MARCH 2013 UK £3.99 USA $9.99 INSIDE COMMANDO R O C K E T G O L D STA R & BO N N E VI LL E HOW GOOD ARE THEY? + HOW TO BUY INTO THE DREAM R80G/S DAKAR Why this BMW is COME AGAIN? the perfect classic “I built a supercharged flat-four two-stroke racer in my shed” KAWASAKI Z1 ENGINE STRIP Inside the motor that made the 1970s faster “I HONED MY SKILLS ON THE CATERHAM BYPASS” Hard-charging Rex Butcher’s race career Three generations of the fast British twin On top of the WORLD Words: ben miller. Photography: jason critchell Half a century ago fast British twins offered a worldbeating blend of speed, style and charisma. But just how good were they, and did the concept evolve at all from 1950s pre-unit BSAs to 1970s Norton Commando? 38 39 Three generations of the fast British twin Great British singles part 2 bsa rocket gold star replica The RGS was the ultimate evolution of the 1950s twin. This replica isn’t bad either Engine air-cooled, four-stroke 646cc twin Chassis twin-loop steel cradle, twin shocks, telescopic forks The numbers 40bhp, 110mph, 423lb (192kg), £5000 T he most desirable of BSA’s myriad twins, the This BSA demands absolutely no acclimatisation whatsoever. Rocket Gold Star was built for just two years Much of the credit must go to the chassis geometry – the A10 (1962 and ’63) and combined twin-cylinder has always enjoyed a reputation as a fine bend-swinger – and, Super Rocket power with the fabled handling of by modern standards certainly, the ludicrously narrow rubber. the Gold Star sports single. Being rare and very The result is completely intuitive handling from the first corner. expensive, genuine bikes are now outnumbered by replicas. There are no oddities to work around, no brain-troubling This machine is fairly typical of the breed, with a genuine sensations of flopping-in or standing-up, just easy steering and Super Rocket engine (an evolution a reassuring feel from the tyres. of the 1950s A10 motor, with an ◗ Cute Smiths chronometrics sit above genuine RGS headlamp The riding position helps, too. brackets and A10 forks. Slim pipe around filler is a breather alloy head, increased compression The seat feels high and the fuel and lumpier cams) strung between tank relatively short, giving a 19in wheels using a good number perfectly-balanced riding position of parts plucked from the BSA as you lean forward to the narrow parts bin. While inarguably not and low-set handlebars. You feel the real deal, this machine is plugged-in and part of the action representative of the stage the fast before you’ve even turned a wheel. British twin had reached by the And the engine is a joy. It is not end of the 1950s, with its pre-unit fast – not compared to the engine and gearbox combined Bonneville and certainly not with 110mph performance. compared to the Norton – but it is Oh, and plenty of style. What a all you need, with enough guts to fantastic looking bike. Of course give you the choice of two gears for the sunshine helps – welcome to most corners (shift down and ride winter, Mallorca-style. The air is the revs, or drive though letting the warm and clear, the sky is a torque do the work) and the most luminescent Sistine ceiling of wonderful linearity to it; twist flawless blue and the light is more, get more. Simple. textbook Mediterranean; all softA genuine Rocket Gold Star diffused brilliance and Polaroid would be faster (especially fulllens flare. Ahead the fiendishly house examples with fruity racing twisty C710 coast road snakes carbs and the close-ratio RRT2 north-east, wriggling between ’box) arguably at the expense of huge drops to the sea and sunthe flexibility that makes this bike dappled glades of pine. Preso nice to ride, but there’s a lot to recession European Union be said for a good replica. As spending means the tarmac is Hugh, this bike’s owner, says: “If racetrack-standard. it was a genuine one, I don’t think There is no traffic – the package I’d be quite so happy letting clients holiday season is months away – ride it [Hugh runs Albion ◗ Arguably not quite as handsome as the real deal, but a fair and no noise. I swear the loudest Motorcycles, offering guided bit more affordable and usable. And it’s hardly ugly, is it? noise I can hear is the little spurt classic motorcycle tours on of petrol hitting the dirt as I tickle Mallorca – more on page 45] and the BSA’s carb. Not for long. With a good kick, the engine its value might also keep me from putting too many miles on it. shatters the serenity like a rifle shot through a fine vase. The I like the fact that I don’t have to worry about this one, I can noise is beautiful, rich and mellow through the siamesed pipe. just ride it. That usability is more important to me than Up into first gear and, with a final mental note to ride on the authenticity. And my clients love the bike as it is. It looks the right-hand side of the road, we’re off. part, it sounds fantastic and rides like a good British twin The first few miles aren’t to be hurried. With my goggles up, should – nimble, involving, fun.” I savour the feeling of warm sunshine on my face and a dry I can see their point. While a genuine Rocket Gold Star is road beneath me – it’s been a while. Occasionally, through something special, a race shop-developed factory special with breaks in the trees, I snatch glimpses of shimmering sea the kudos of being rarer than Parisian steak, a good replica is hundreds of feet below – is the mist-shrouded Gatwick airport pretty tempting too, with a lot of style and charisma for what we left behind this morning really on the same planet? is, by Bonneville standards certainly, very sensible money. 40 ◗ Non-standard 8in twin leadingshoe front brake is a decent stopper once set up properly. Plus the fine handling means you rarely need to use it... ◗ The standard Super Rocket engine uses an 8.5:1 compression ratio. Genuine RGS motors bump that to 9:1. A sports camshaft was offered, too 41 Three generations of the fast British twin “Cyclists give you the thumbs-up. Girls in cabriolets smile shyly. Life – rub a little Triumph Bonneville on it” Triumph T120 bonneville The world’s most famous British twin and the epitome of 1960s speed and style Engine air-cooled, four-stroke 649cc twin Chassis single-downtube cradle, twin shocks, telescopic forks The numbers 46bhp, 120mph, 385lb (175kg), £7500 W hile the late-1960s Bonnies are reckoned to be the Esporles, still I’m torn – ride the road and tear my gaze from finest, with their more effective front brakes and the views or kick back, shift up and just enjoy the moment. revised chassis geometry, the truth is that the best The great thing about the Triumph is its puppy-dog of any gaggle of Bonnies is likely to be the one in enthusiasm for either approach. If you want to cruise, the bike’s most regular use. I’ve tended to find myself on comfortable and mild-mannered enough to do so. And, thanks cosmetically flawless but mechanically wayward examples that perhaps to the badge on the tank and the bike’s timeless haven’t lived up to the legend. But Hugh’s bike is in very silhouette, it also has a magical ability to make the world regular use, clocking up hundreds around it a better place. Passing of miles a week for eight months ◗ The Triumph’s motor has a 8.5:1 compression ratio and serves packs of cyclists, none of whom up 46bhp smoothly – if those twin Amals are properly set up of the year – and you can tell. gave a monkey’s about the BSA, This is a 1964 machine. The offer a thumbs-up. Girls in Bonneville moved to unit cabriolets catch your eye and grin construction a year earlier, and shyly... Life – rub a little Triumph also gained coil ignition, new Bonneville on it. forks and a revised frame with But, of course, the Triumph can single sturdy downtube. This also get a shift on. Come the early machine, resplendent in gold/ 1980s the great name was being Alaskan white paint, is typical of used to sell actual cruisers, bikes the kind of bike you’re likely to like the mag-wheeled, go-fasterfind on a sensible budget; striped and inexplicably attractive matching-numbers correct, but American-market TSX, but bikes restored and with the odd part like this one were out-and-out from elsewhere. The tank and sports machines. And it shows. forks are ’68, as is the fine twinHold each gear longer, rev the leading-shoe front brake. smooth and soulful engine a little By this stage in its mammoth harder, through peak torque and production run (1959 to ’83 into the meant of the power, and initially, followed by a few false the world begins to scroll by starts and then, in 2001, the appreciably faster. Hinckley bikes) the Bonneville When a corner arrives, turn-in was in the ascendancy, recovering on the Triumph feels almost from a lukewarm initial reception weightless. Of course, it isn’t – far to become a strong seller the from it at around 385lb (175kg) – world over. Triumph had woken but something about the machine’s up to the truth that affluent, slim build and balanced chassis performance-hungry US makes honking on effortless and customers wanted what was hugely enjoyable. When riding like essentially a faster Trophy. this, the Bonneville’s class really For 1960 the deep mudguards shines through. All those years of ◗ Bonnie’s stuffy nacelle had disappeared by 1960, leaving a and stuffy headlamp nacelle were development, all that racing R&D satisfyingly clean rider’s view past the twin Smiths clocks dropped and 1963 saw the arrival and all those thousands of testof 18in wheels front and rear for rider miles mean that the Bonnie quicker steering. Now the Bonnie was ready to take over the never wilts, however carried away you care to get. That it can world. It was handsome, fast and fine-handling, and a worthy do this, and yet still bimble comfortably, is impressive. successor to the café-racing, youth-goading Tiger 110 of the Within a decade of this bike’s manufacture (June 5, 1964) 1950s. Sales duly soared from 200 bikes a week to 1300. the Bonneville was fighting an impossible war, growing to Climbing aboard, the Triumph feels immediately welcoming, 750cc with the T140V in ’73 but losing in smoothness, style offering sir a long, broad and comfortable seat, some just-so and balance anything it gained in speed. Perhaps a mid-1960s ’bars and a great view from the hot seat, with the parcel rack Brit twin like this is as good as it gets. The BSA feels a shade and twin Smiths clocks shimmering in the morning light. This under-gunned by comparison, and the later Commando, while easy-going character extends to the swift-shifting gearbox, the fast enough to curl your toes and stay with anything this side strong but never-intimidating engine and a light, direct steering of a Z1, is an all-or-nothing hard-charger. feel. Halfway up the coast road now, making for the town of The Triumph always delivers, however you choose to ride it. 42 43 Three generations of the fast British twin Be here now The Albion Motorcycles formula is simple but effective: great bikes on fantastic roads with good weather and all the distractions of the island of Mallorca on hand when you’re not riding. Flying out can cost as little as £50 with one of the budget airlines and for 180 euros a day you get the bike of your choice (the Albion fleet includes the three bikes you see here, plus another five – visit their website for the full rundown), insurance and riding kit, should you want it. What you do with your time is entirely up to you. Hugh Birley, the man behind Albion, knows the island’s food and roads intimately, and can create the perfect itinerary for you. He’s also a good egg, handy with the spanners and gifted at ordering wine. Call 0034 971 180783 or visit www.albion motorcycles.com for more details. More on Albion in the April 2013 issue, on sale 28 March. 44 45 Three generations of the fast British twin Great British singles part 2 norton 850 commando Big cubes and a clever frame kept the British twin relevant into the 1970s Type air-cooled, four-stroke parallel twin Chassis tubular steel double cradle, twin shocks, telescopic forks The numbers 60bhp, 125mph, 395lb (181kg), £6500 I t’s a classic David and Goliath scrap. I’ve jumped often means inviting lumpiness on a lunar-landscape level. on the Commando and Hugh’s riding buddy Norton-Villiers tackled the problem by treating the engine, Brendan’s taken the Triumph. As the road moves gearbox and swingarm assembly as one rigid unit, and inland, climbing steadily in a series of gorgeous, mounting it within the rest of the frame using isolating mounts sweeping hairpins, it’s clear Brendan’s found a that allowed the engine to shake but kept it aligned with the groove. He may be new to classics, and still adapting to a rightframe. The system, which comprises a series of rubber bushes, foot gearshift, but he’s no stranger to fast twins, having owned sleeves, spacers and thrust cups on long bolts, let the bulk of a 900SS Ducati until recently. the engine’s vibrations dissipate Crucially, being a resident, he also ◗ Norton made a better fist of taking the British twin into the while still retaining the chassis future than anyone else, but Z1s and Jotas were tough rivals knows these roads well. rigidity and integrity required for From the seat of the safe, consistent handling. The Commando, giving chase, I can’t Commando’s frame also canted help but smile. Like bringing a the engine forward, improving blunderbuss to a knife fight, the weight distribution – a forwardNorton’s 850 motor (actually biased split gives more confidence 828cc, up from the earlier 750’s in the front tyre – with the happy 745cc courtesy of bigger bores – side-effect of emphasising the 73mm to 77mm, stroke stayed the bike’s already rakish lines. same at 89mm) feels like a Your instincts tell you the chassis distinctly unfair advantage. Poor shouldn’t work. It’s a solution that old Brendan can brake as late as smacks of compromise and of he likes and carry as much corner making-do. But the Commando speed as the Triumph’s ground was a (ahem) triumph. The bike clearance can muster, but when won critical acclaim from the press the bends open out, as even these for its speed, handling and fiendish sequences must comfort, it raced successfully and eventually, the Commando simply in its myriad guises it sold strongly. shudders, squats slightly as the It appealed to enthusiast riders torque comes in with a wallop with too much flying time on and, without breaking a sweat, British twins to get their heads pulls back any lead the Triumph around the new breed of the inline may have eked out. No fuss, no triples and fours that were by then problem. You could argue the winning the war of impressive Commando’s ingenious enginespec-sheet numbers. isolating frame may not have the Back to the here and now, and ultimate feel or poise of the earlier there’s no denying the Commando Featherbed, or of Triumph’s is a significant step forward over highly-developed cradle, but when both the BSA and the Triumph. It’s the engine it holds has this much considerably quicker and more ◗ Separate gearbox was, by 1974, a quaint idiosyncrasy. Foursheer grunt it just doesn’t matter.  practical as a result. You could do speed unit is driven by a triplex chain. Carbs are Monoblocs The Commando is arguably the anything on one of these – tour ultimate evolution of the sporting Europe, take it round a racetrack British parallel twin (Weslake/Nourish may beg to differ). or, if needs be, put in a few motorway hours. The Norton’s Engineered by some brilliant minds, including former Rollshandling and braking performance are a match for the engine, Royce man Dr Stefan Bauer, and steered by the irrepressible too, the recently-rebuilt Lockheed front discs on this bike Dennis Poore, the Commando project was simple. The bike giving the confidence to brake late and hard. had to be fast enough to appeal to performance-conscious A whitewash, then? On performance alone, you have to say riders, but it had to summon that speed using a derivation of yes – but in 850 guise in particular, you’ve got to be up for fullNorton’s venerable parallel twin – an engine that had been in throttle lunacy most of the time on a Commando. With its service since the 1940s, first as the Model 7 and latterly in hair-trigger throttle response, lunging delivery and firmly745cc form in the Atlas. The resources weren’t available to damped chassis, the Norton’s fairly all-or-nothing. Sound like design and develop a multi-cylinder engine, as the competition your cup or tea? Excellent – you and the ultimate incarnation was doing. Vibration would be the issue – tuning parallel twins of the sporting British twin will get along just fine. 46 ◗ You beauty. A Roadster in black or yellow has to be the prettiest of the Commando’s many guises. The Interstate carries twice as much fuel, handily, but the 5.5-gallon tank is hardly elegant 47 Three generations of the fast British twin Words: Gerard Kane & Alan seeley buy into the bRitish Twin dream Feel the need to own a legendary British twin? Of course you do. Here’s how to buy a good one 48 BSA A10/Rocket Gold Star Triumph T120 Bonneville Norton Commando Any A10 with the 1954-on swingarm frame offers sure-footed handling, decent reliability and adequate performance. The 1954-63 Road Rocket, Super Rocket (introduced in ’58) and the Rocket Gold Star offer more speed and glamour. The main weakness of the A10 engine is the plain bush timing-side main bearing. A ball and roller bearing conversion with oil feed through the crank end is a wise investment. If the bike starts easily when cold but not when hot, suspect the magneto. A rebuild will cost £400. Marginal 6-volt electrics can be improved with a 12-volt conversion. The Rocket Gold Star is the ultimate A10. Genuine bikes are now £20,000, so make sure you’re buying a real one. Essentially a Super Rocket engine in a Gold Star-type frame (though without the kink in the lower right-hand frame rail), RGS frames are prefixed GA10 and heavily gusseted around the headstock. They also have forged (rather than welded) front engine mounts (as do later A10s) and there should be welded-on mounts for the rear sets. The rest of the spec is easier to fake, so contact the owners’ club – www.goldstarownersclub.com The 1960s T120 is the finest flowering of the Bonnie species. First-season ’59 models are hideously expensive, but a mid-1960s bike is a better bet if you’re buying your first British twin. Budget £6000-8000 for something in good order and ready to ride. All unit-construction Bonnevilles have alternator electrics (as do post-’59 pre-unit bikes) and coil ignition, while ’66-on bikes have 12-volt systems as standard. They’re surprisingly quick, with a near-120mph top end and strong acceleration. The lack of weight helps in this respect. For the best riding experience, go for a 1968-1970 model. They boast punchy engines, cheap and available Amal Concentric carbs (replacing Monoblocs) and an excellent twin-leading-shoe front brake. The revised 1969-on front brake arm gives a neater run for the cable and a better feel at the lever. Electrical components can fall foul of big-twin vibes, so a solid state regulator is a good investment. Electronic ignition kits are also available. Reliability is generally good, but check for adequate compression. Upgrades and mods are legion, but a good T120 doesn’t need them. Look after one and it will both surprise and excite you. Prices are on the rise but the Commando remains attractive compared to some of the rarer Bonnevilles and an absolute steal alongside exotica like the BSA Rocket Gold Star. Their sheer usability means they’re the untapped classic bargain – good bikes can be had for around four grand. Modifications proliferate, and some undoubtedly improve the riding experience. A vibrant aftermarket continues to upgrade the Commando while ensuring easy spares supply. The original horseshoe calipers fitted to disc-brake models are hopeless – many aftermarket solutions are available, some more congruous than others. A Peter Williams PW3 camshaft will pep up an already lusty engine. A belt primary will smooth the transmission while MkIII-type vernier adjusters make adjusting the Isolastics a breeze. For those chasing the Commando experience in the raw, a ’72 Combatengined 750 is the one. Ignore the Combat engine’s fragile rep; they’re all sorted now. A MkIII 850 Commando, introduced for 1975, is the best choice for those used to modern bikes. With disc brakes front and rear, left-foot gearchange and an electric starter, they’re almost modern.