Time to come in from the COLD

When Honda launched the VF750S shaft-drive vee-four in 1982, we never realised how much of an impact it would have on the factory's fortunes. John Nutting reckons the engine problems were exaggerated and, 20 years on, it's time for the early V4s to receive proper recognition.
HONDA’S current range provides a selection of engine configurations to suit any taste: screaming fours, melodious vee-twins, flat sixes, mundane twins, lithe singles, and fluid vee-fours. The choice is yours, but in the UK there are just two vee-fours.
Once however, Honda threw its all into the vee-four design. In a bid to make its mark in a world of ordinary straight fours, it offered a whole range of vee-fours, from 400cc to 1000cc, and clothed them in sports, custom and cruiser bodywork.
But the strategy was undermined by a series of mechanical gremlins that forced Honda to eventually save face, first with the CBR600 and CBR1000 models of 1987 that were the initiators of the modern liquid-cooled, in-line design and the phenomenal CBR900 Fireblade of 1992.
In the meantime, Honda’s superbike and endurance racing efforts had been based on the vee-four, using as a platform the sublime RC30 of 1988 and the later less seductive RC45.
Sack loads of money and engineering effort brought some success on the world scene but at nothing like the level Honda usually achieved. In contrast, when Honda’s RC51 vee-twin was launched two seasons ago, it won the world superbike series first time out.
It would, however, be a mistake to assume that the vee-four is a cul-de-sac in motorcycle design. It is as musical as a vee-twin yet more compact: it is in fact smoother. The trouble is that the vee-four is much more expensive to make than an in-line four for only a marginal improvement in user-friendliness. It is likewise more costly to manufacture than a relatively simple vee-twin.
But Honda has often made a virtue of being different. Its engineers overturn accepted design fashions to demonstrate their prowess. Remember the CX500 Turbo? Or the NR500 oval pistoned racer?
Now it’s playing with a vee-five for Grand Prix racing. Just to be different.
In the beginning
AND so it was when Honda’s first vee-four was introduced at the end of 1981. Its 16-valve, in-line 750cc/900cc/ 1100cc CB series had served the factory well since 1978, when they replaced the original CB750. But everyone had aircooled in-line fours and good though the CB750F was, a different, if not better, solution was on the horizon.
It was a change in strategy that was to blight Honda’s image for more than a decade.
My first contact with the vee-four VF750S was just before the Isle of Man TT in 1982 while I was editor of the monthly Which Bike? magazine. In retrospect, it is likely that Honda was softening up the market for what was to follow because the VF750S was like no high-performance 750cc four we’d ever experienced. As with the flat-four Gold Wing when it was introduced in the Seventies, we didn’t quite know what to make of it.
Brainchild of Honda engineer Sato-san, the bike was long and low and came with shaft drive. When I’d adjusted the handlebars so they were swept back comfortably to match the highish footrests I felt like I was perched on a race horse.
It was fast enough and smooth, and the exhaust note intoxicating. On the way up to Liverpool to catch the boat to Douglas, I marvelled at the instrumentation with its dot-matrix displays and the bike’s comfort and rock-like stability.
On the Island’s twistier roads, the combination of the VF750S’s 61.5 inch wheelbase (longer than a Ducati 900SS) and lanky suspension (using a Pro-link rear shock and a beefy front fork raked back at 60.5 degrees), showed it was ill-suited to sports riding and would pogo alarmingly through bends.
Afterwards I wrote: “In a straight line the vee-four was rock steady, and as long as the road surface is reasonably smooth, the bike retains its composure. Push it hard over tarmac that’s less than well-maintained however and the vee-four plays rough, reacting with a feedback that suggests to the rider he’d better back off.”
It was a strange confection
HONDA’S engineers had either been down the same design road as Ducati and struggled to fit the vee-four engine into the chassis without using a long wheelbase to prevent the front wheel tangling with the leading cylinder head; or they had wanted to design a stretched-out hot rod.
The engine was certainly novel. The two banks of cylinders were set at 90 degrees and were part of the crankcases. A bore and stroke of 70 x 48.6mm offered high safe revs and compact combustion chambers with a high 10.5 to 1 compression ratio.
Watercooled, the cylinder heads had four valves per cylinder and chain driven overhead camshafts. Feeding them were two pairs of 32mm Keihin CV carbs drawing air through a plenum chamber that sprouted either side of the 18 litre fuel tank.
Unusually, the crankshaft had two throws in line and rotated backwards, driving a hydraulically-operated clutch through gears and a six-speed gearbox. Two sets of spiral bevels drove the rear wheel.

‘Sumo bike’ SWANSONG

Kawasaki’s watercooled GPz900R kissed goodbye to the beefy aircooled fours and these are two of the last. Rod Ker slings his leg over a brace of ‘fast lorries’ of the early Eighties.
ETTORE Bugatti is supposed to have said that pre-war Bentleys were like very fast lorries. Borrowing the allusion many years later, TV’s ‘Mr Perm’, Jeremy Clarkson, said the same thing about Ferrari Daytonas.
Somehow this little witticism always springs to mind when I think about big Japanese bikes of the late Seventies and early Eighties. Yamaha’s XS1100 started the trend and the various Suzuki GSX1100 and Kawasaki GPz1100 variants brought the express trucking era to a close.
To qualify for the fast lorry club, you needed at least a litre of transverse four developing around 100 horsepower, 500lb or more of dry weight and a wheelbase of about 60 inches. An underseat storage compartment for Yorkie bars was not ‘de rigueur’, incidentally.
In the class of ‘83, the Suzuki GSX1100ES and Kawasaki GPz1100 Uni-Trak represented the ultimate in high-speed haulage. No-one could possibly doubt the ‘fast’ part and a tape-measure and weighbridge confirmed the rest.
The Kawasaki has an extended family tree that can be traced back to the 903cc Z1 released in 1972. 1980 gave us the Z1000H, a 540lb, 1015cc beast that looked very like any other Zed Thou until you noticed the absence of carburettors - fuel injection had finally reached motorcycling (with apologies to Wal Phillips). In practice, the high-tech induction apparatus made little difference.
Kawasaki only claimed a measly one bhp bonus and road test figures didn’t necessarily prove the existence of even that nominal gain. What they did find was less welcome - increased fuel consumption.
So the H wasn’t exactly a giant leap forward but it did pave the way for the GPz1100 series which kicked off in early ‘81 with the B1 model. The claimed output was 108 bhp, enough for standing quarters hovering around the 11.5 second mark and a top speed nudging 140mph.
A complete restyle helped too. Gone were the dull metallic paint jobs and dreary graphics of recent years. In came bright red paint, tank stripes and a contrasting black engine. The exhausts were also supposed to be black but they had an unfortunate tendency to turn a subtle shade of puce after a few trips in the rain.
Kawasaki revival
ROAD testers were full of praise. Although even bigger than the old King, at 525lb dry it was a bit lighter and substantially faster. Despite a few reliability scares, it’s true to say that Kawasaki’s flagging big bike sales were revived by the GPz1100, with a knock-on effect on smaller models.
In 1982 the B2 appeared, complete with handlebar-mounted mini-fairing. Inside lurked a totally revised set of instruments, including some liquid crystal gauges, in those days the last word in space-age technology.
The other visual change was that the matt black paint on (or usually off) the exhausts was now `black chrome’, a better finish, even if it still gave Kawasaki plenty of warranty claims.
The third and final GPz1100 incarnation, as seen here, was the Uni-Trak model announced in 1983. This time King Zed’s revamp was comprehensive. Although the engine was still very similar to the original Z1 unit in essence, power was now up by about 50 per cent and 120 bhp at 8750 rpm was quoted, achieved through extensive work on the cylinder head.
The frame was substantially revised, partly to accommodate Uni-Trak rear suspension, partly to make it stronger. New to road bikes, the Uni-Trak was related to the set-up used on the Godier/Genoud endurance racers of the Seventies. After transferring to motocross, the idea eventually migrated back to tarmac on the GPz range.
The linkage used on the 1100 was different from that on the smaller bikes, and in theory less efficient. Perhaps what mattered more was that the air-assisted shock was attached to a strong, well supported box-section aluminium swinging arm.
Some American mags managed to record standing quarter times of under 11 seconds but the British failed to match that. What impressed us over here was a top speed close to 150 mph, reflecting the revviness of the tuned engine.
Less than a year after the 1100 Uni-Trak debuted it was relegated to the background. First Kawasaki released the 750 Turbo, which was faster, smaller and far more fun to ride, then they unveiled their 900 Ninja, heralding a new age of watercooled sophistication.
Track winner
SUZUKI’S Suzuki’s GS series of fours arrived in 1976 with the 750 followed by 550cc and 1000cc models. The GS1000 fought it out with the Z1000 until 1980, when Suzuki released the considerably different GSX1100. The X denoted four valve heads with ‘Twin Swirl’ combustion chambers fed by gulping great 34mm Mikuni CV carbs.
To increase capacity Suzuki had upped the stroke to 66mm, claiming 100 bhp at 8700 rpm. There’s no doubt that the GSX handled and went at least as well as any other 1980 bike. To prove it, many were soon seen on tracks, winning races. Yet the 1100 was not exactly dainty and the slabby, rectangular styling did nothing to disguise the fact.
After a stunning redesign gave us the Katana, 1983 saw the launch of the bike featured here, the GSX1100ES, complete with half fairing, black engine, new instrument console and one of Suzuki’s favourite ‘ice cream van’ colour schemes, echoing the look of the earlier GS1000S.

The pain and the PLEASURE

This modified Morini Sport can trounce bigger bikes in the handling stakes - if you can stand the pain of the riding position! In the world of Morini, no two bikes are the same. Brian Tarbox explains why.
JASON Lake’s 1975 Morini Sport is a gem. The fact that it features too many mods to be regarded as a concours classic is of little matter. Most Morinis are rebuilt to be ridden rather than displayed which is why it took top honours at the Morini Riders’ Club’s annual festival this Summer (see Mechanics, August 2001).
Club members choose their own champion and no one is too obsessed with factory originality. Jason, a member of the club for seven years, said: “I don’t think I have ever seen a totally standard Morini. Every owner has made changes of some kind.”
Alex Mayhew, workshop manager at North Leicester Motorcycles, runs a highly tuned 507cc motor in a Strada frame with Valentini bodywork. With a top speed of around 125 mph it is probably the most potent Morini on UK roads.
Morini specialist Phil Smith (0208 542 8771) prefers Stradas to Sports because the power comes in at lower rpm and the riding position is more comfortable. He says the best hybrid he made for a customer involved the marriage of a Strada frame and X1 Kanguro engine, the trail bike motor boasting Nikasil barrels and an ‘M’ camshaft with profiles midway between Sport and Strada spec. In short, anything goes.
The Sport and Strada (see model history) share the same frame and suspension and most owners list superb handling as the most outstanding feature. The steering damper introduced on the Sport was merely a fashion accessory and Jason is among many owners who have stuck it at the back of the garage.
It certainly doesn’t seem necessary. Along twisty back lanes 350 Morinis can humble many far bigger and more powerful machines. It is one of the reasons Jason is a fan, but the 32 year-old from Norfolk says a 3 1/2 Sport went on his wanted list because of its look and sound. He was a teenager at the time and a friend on the same engineering course at college was a Morini owner.
He describes the 100 mph performance as “pretty good for a machine of its size and age” and says the only major drawback is the uncomfortable riding position. The combination of clip-ons and standard position Strada footpegs on the original Sport was a marriage made in hell.
The pegs were moved back several times on subsequent models, but never quite far enough. Jason’s machine has home-made rearsets fitted by the previous owner but he says the bike still has to be ridden hard to detract from the pain.
Stunning result
JASON bought the bike from his old college friend about seven years ago. Stripped but complete and with the engine already assembled, it cost him £1250. He quickly got it back on the road but rebuilt it again a few years ago.
It had started missing gears so he decided to start from scratch with a complete engine rebuild. A service manager with a tower crane company and experienced diesel engine mechanic, he tackled the job himself. Total outlay, including the original purchase price, was about £3000 and the result is stunning.
The good news for anyone planning a similar project is that North Leicester Motorcycles (01530 263381) are the world’s leading Morini parts specialists. They stock more than £500,000 worth of spares and have commissioned the re-manufacture of many components.
All genuine Sport engines are stamped with an ‘S’ below the right-hand side of the front cylinder barrel but only official UK import Sports and Stradas have engine numbers and many of the machines now available are used examples first sold in Italy.
Just what components were originally used on any particular model is a little iffy as the factory had the habit of using what was available on their parts shelf at the time of assembly. The good news is that all the upgrades made over the years can be fitted retrospectively.
Jason’s gearbox problem was due to wear of the original alloy selector forks. Morini tackled this in about 1976 when they introduced harder-wearing phosphor bronze replacements. You need three of them costing about £120 plus VAT.
Another modification the factory made around the same time was to fit a plain bearing in place of a ball-race on the timing side of the crankshaft because of reports of excessive wear due to thermal expansion. An oil leak from that side of the engine is an early sign of failure.
Jason opted to stick to the use of a ball-race and experts say there shouldn’t be any problem providing the oil is kept fresh and the sump clean of sludge. All bearings in the engine are standard sizes and can be bought off the shelf from any supplier.
All but the camshaft bearings are C3 spec. Jason had his crankcases and barrels vapour blasted by R D Cox and Son (01189 750289) and the crank reground at the K L Engine Centre in Norwich (01603 748999). The Centre now charges £28 to regrind the big end journals on a twin and £40 for a four.