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Crosby Moriwaki Replica - Limited Edition - #6 of 10

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Moriwaki Monster - An especially built replica of the 1979 World TTF1 Championship Entry (3rd place) 1979 - Limited to 10 numbered units

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Description

Kawasaki Z1B Moriwaki review

Wild and vibrant roadster

4 cylinders in line, 1,135 cm3, 119 hp, 160 kg

It has been exactly 40 years since New Zealander Graeme Crosby entered the GP 500 as a factory Suzuki driver for the team led by British importer Heron Suzuki. He was only 24 years old! His arrival on the British racing scene in 1979 caused a sensation, because of the motorcycle he was riding, the very straight and non-faired Kawasaki Z1B Superbike with its high handlebars which had been prepared by the small Japanese company Moriwaki then unknown.

Remember, the Superbike discipline had only been invented in the USA three years earlier, with a first race contested in Daytona in 1976. This naked 4-stroke monster had not had time to migrate to Europe. Anyway, the British federation had invented the TT Formula 1 in 1977, with production engines prepared in a racing chassis, in order to save the world championship status of the Tourist Trophy. It also meant that American-style Superbike racing wouldn't have its place for a decade. So, at that time when the full fairing and the handlebars straps were considered to be de rigueur on a racing motorcycle, here is a New Zealander out of nowhere, sitting very straight on his Japanese road motorcycle, with no dressings outside of the small fork head, came to face the local stars like Mick Grant and Ron Haslam who evolved them on the factory Honda. As one commentator pointed out at the time, "only a victory for a custom at the Senior TT would have made more noise!"

Moriwaki Kawasaki Z1B review
Moriwaki Kawasaki Z1B review

Genesis

Croz 'was one of the most versatile and talented pilots of his generation. He was also one of the most spectacular drivers the world has ever seen, making his mark on world-class road racing in just four years. He thus exploded on the international scene in 1979 riding this improbable Kawasaki superbike on which he finished between the two Honda by finishing second in the British TT F1 championship. This earned him a contract for the factory team Suzuki in 80/81 in 500 GP and TT F1, allowing him to win the TT F1 world championship and to win three times on the Isle of Man. Nothing less ! In 1982, he joined the Yamaha team newly formed by World Champion Giacomo Agostiniand won the Daytona 200 for its first race. But although he finished second in the championship that year, Croz was then discouraged by GP policy, so that he packed his bags and returned to New Zealand at the end of the season, withdrawing permanently from competition as its star was just beginning to shine in the Grand Prix galaxy.

Crosby on the Moriwaki Kawasaki Z1B during the 1979 Ulster GP
Crosby on the Moriwaki Kawasaki Z1B during the 1979 Ulster GP

Famous for his gimmick when he arrived on each new circuit, "which way is the track going and what is the lap record? ", Croz played his role of hero of the people. In addition to his regular wheelings which enchanted the crowd, his drifts from the back and his breathtaking overtaking, he was also noted for his spiritual replicas Combined with his carefree charm and his confidence, his sense of spectacle made him a pilot unanimously appreciated by fans around the world, with this ability to bring star pilots back to earth, both on and off. the track. His antics and gaiety reflected a seemingly nonchalant approach to racing, but one that actually masked the analysis of a fierce rival. Croz was running to win.

The history of road racing has known several iconic rider and motorcycle duos, such as Ago and the 3-cylinder MV , Mike Hailwood and his TT Ducati or even Mick Doohan on the Honda NSR500 . Graeme Crosby and the Moriwaki Kawasaki Z1 are on this list, especially after seeing him at work for most of the 1979 season, both from outside the track as a friend and a fan, but also closer was directly behind him on the starting grid of the TT F1 heats on my P&M Kawasaki.

I was lucky to be able to ride this bike on the Pembrey track in south-west Wales and thus answer a question I had been asking myself for 40 years: How well was the Moriwaki Kawasaki and what role did it play in Croz's rise to the top?

Graeme Crosby at the Festival of 1.000 Bikes in Mallory Park
Graeme Crosby at the Festival of 1.000 Bikes in Mallory Park

Discovery

Since the rules of TT Formula 1 limited the maximum displacement to 1,000 cm3 for the 4 stroke (and 500 cm3 for the 2 stroke), Mamoru Moriwaki could not use the Kawasaki Z 1000 introduced in 1977 as the basis for his TT F1 motorcycles . It had indeed a 1.015 cc engine. So he based the Crosby Superbike on the 1975 Z1B air-cooled engine., measuring 66 x 66 mm with a displacement of 903 cm3 with two overhead camshafts and mounted high compression pistons of 69.4 mm to reach 998.64 cm3 with a volumetric ratio of 11.5: 1. But when Gordon Pantall restored the engine, Moriwaki could not supply these pistons. He therefore mounted 74 mm Omega pistons on standard connecting rods, the cylinder being hollowed out to offer a final capacity of 1,135 cm3, or 14% more than on the Crosby version.

Kawasaki cube four-cylinder engine now at 1,135 cc
Kawasaki cube four-cylinder engine now at 1,135 cc

The eight-valve cylinder head with double overhead camshafts has been extensively reviewed by Moriwaki in Japan by being fitted with racing camshafts operating on oversized steel valves of 37.5 mm at intake and 31 mm at the exhaust, carrying robust springs via inverted horns from Z650. Although according to the TT F1 rules, Crosby was obliged to use the small Mikuni carburetors 28 mm road from the Z1B, for the races in Open class he mounted Keinhin CR of 32 mm race, which one still found on the machine today. An exact replica of the original Moriwaki 4-1 racing exhaust was purchased in Japan, with the exception of the aluminum silencer which replaces the original steel silencer. After encountering problems with the ignition of Pantall originally fitted a Dyna S electronic CDI powered by a 12V battery. The result is an engine that has been bench tested at 119 hp at 9,000 rpm. A Kawasaki five-speed short gearbox helps transmit this power to the ground via an original oil-bathed multi-plate clutch.

Keihin carburetors in the revised Z1B engine
Keihin carburetors in the revised Z1B engine

For the debut of the Moriwaki in racing during the 8 hours of Suzuka in 1979, this same prepared engine was mounted on a frame of Kawasaki Z1B modified with a hunting angle open of 2 ° additional compared to the origin for more stability . Triple T of Z650 were used, with a reduced offset for an elongated flush to 108 mm against the 90 mm stock. While changing the geometry of the steering, Moriwaki also stiffened the chassis with a bracing around the steering column and the front engine support. It is this same modified Z1B frame that is still present on the bike, with additional reinforcements. There is also a Moriwaki swingarm with two Kayaba shock absorbers 330 mm long adjustable on 9 preload levels.

Moriwaki modified shock absorbers are longer and more sloping than originally
Moriwaki modified shock absorbers are longer and more sloping than originally

These shock absorbers are much longer than the original components, they not only help increase the weight forward on the tire, but also offer additional ground clearance, crucial when combined with the large Moriwaki side covers of the motor. The fact that the upper shock absorber supports have also been moved further forward on the frame offers a semi-recumbent position which induces additional progressiveness for the suspension. The 36 mm Kayaba fork with pneumatic preload adjustment has a hunting angle of 28 °. The wide flat handlebar made in one piece is bolted to the upper triple tee by 40 mm bridges providing additional leverage. There is also a Kawasaki adjustable steering damper on the right.

The fork angle was opened at 28
The fork angle was opened at 28 °

The two 296 mm Kawasaki front brake discs in stainless steel remain the only characteristic of the Moriwaki which is constantly troublesome, easily overheating under the bite of AP-Lockheed two-piston calipers, whether on fast circuits like Silverstoneor slower like Scarborough. The 230 mm Kawasaki stainless steel rear disc with single-piston AP-Lockheed caliper ensures an additional slowdown essential to brake the 160 kg claimed dry by this racing bike, against the 232 kg of the Z1B! This weight is also made possible by the 18-inch Morris magnesium rims that have become extremely rare. Gordon Pantall bought them new via the Web when the motorcycle was restored. Their light weight also helps minimize the unsprung weight and therefore improves the tuning of the suspensions. These are fitted with vintage Dunlop racing tires with a KR125 3.50 / 3.25 on the 3 "front Morris wheel and a KR164 3.75 / 5.00 on the 4" rear.

The Moriwaki Kawasaki Z1B weighs only 160 kg when dry
The Moriwaki Kawasaki Z1B weighs only 160 kg when dry

Trial

The Moriwaki took a long time to start in the Paddock ... using the second gear! The first is indeed too low to be used elsewhere than at the start of a race. And this start-up was only done after having drowned the Keihin CR carburettors. Once warmed up, the engine then suffered a failure at high speed on the track, a problem solved by the replacement of a new 12v battery.

But once it runs, Moriwaki's prepared engine offers impressive acceleration for an eight-valve four-cylinder. This is also where the larger 32mm CR carburetors used for the Open category instead of the mandatory 28mm in TT F1 would have shown their interest on faster circuits.

Moriwaki Kawasaki Z1B test on track
Moriwaki Kawasaki Z1B test on track

Taking a seat in the old Croz saddle reveals an unusual riding position compared to other Superbikes from the early 80s that I have been able to ride. With the apparently very high flat handlebars, you have no choice but to ride with your elbows out. But the wide handlebars provide excellent leverage for tight turns on British short circuits, as evidenced by the hairpins from Mallory Park and Pembrey. The protection offered by the small fairing is then surprisingly good for the helmet and the shoulders. But this is partly because you sit low on the bike, as inside, the saddle only peaks at 740 mm, a little lower than on a modern sports car. With the relatively high footrests, this leaves little space to move on the Moriwaki. There is therefore no question of hoping to put the knee in a curve. Look at the photos of Croz at the time and you won't see any sliders, which had just been invented.

Wide handlebar provides good leverage for changing angles
Wide handlebar provides good leverage for changing angles

Gordon Pantall, a former Welsh TT driver, bought the bike in Moriwaki in late 79 and has owned it ever since. But by restoring the well-used Kawasaki Z1 engine, it had not been able to source original Moriwaki pistons of 69.4 mm to restore it to the 998 cc configuration for the TT F1. Instead, he got a 74mm British Omega package, which resulted in a cubed engine now at 1,135cc, with more power and much more torque than in Croz's last race. The lower powered Z1 engine powering my P&M Kawasaki with which I faced Croz and Moriwaki 40 years ago had lower mid-torque than the engine on today's motorcycle today and was also sharper in the way it delivered its power, encouraging to use the short five-speed gearbox to continue to rev up. It was not really a problem with the Moriwaki caliber that I rode at Pembrey and again at the Festival of 1,000 bikes in Mallory Park a few weeks later, in the company of Croz himself (who was riding the Suzuki XR69 from 1980). In its 1,135 cc version, the engine pulls strongly from 4,000 rpm with a linear power supply up to the red zone of 9,000 rpm, as indicated on the counter which remains the only instrumentation present on this air-cooled motorcycle. wasn't really a problem with the Moriwaki caliber that I rode in Pembrey and again at the Festival of 1,000 bikes in Mallory Park a few weeks later, in the company of Croz himself (who rode the 1980 Suzuki XR69) . In its 1,135 cc version, the engine pulls strongly from 4,000 rpm with a linear power supply up to the red zone of 9,000 rpm, as indicated on the counter which remains the only instrumentation present on this air-cooled motorcycle. wasn't really a problem with the Moriwaki caliber that I rode in Pembrey and again at the Festival of 1,000 bikes in Mallory Park a few weeks later, in the company of Croz himself (who rode the 1980 Suzuki XR69) . In its 1,135 cc version, the engine pulls strongly from 4,000 rpm with a linear power supply up to the red zone of 9,000 rpm, as indicated on the counter which remains the only instrumentation present on this air-cooled motorcycle.

Four-cylinder engine now delivers 119 horsepower
Four-cylinder engine now delivers 119 horsepower

Croz had warned me of the damage that a missed report could cause. Fortunately, the gearbox settings are flawless, even by today's standards. Coupled with the easy-to-operate clutch, the gear change is simply instinctive and is accompanied by the howling of the Moriwaki 4-in-1 exhaust. I had forgotten how noisy our F1 TT four-cylinder motorcycles at the time, at the beginning of the mandatory silencer! I still had short-shifterentering the triple left in front of the paddock of Pembrey to avoid scraping my left boot on the track while trying to descend a report on the lever while being still on the angle, to catch the fourth while taking the direction of Esses. The torquey nature of the engine allows you to do this, but it illustrates the risks of keeping a road configuration as so many Australians and New Zealanders have done, from Croz to Wayne Gardner via Chris Vermeulen. But hey, they all became World Champions!

The Moriwaki Kawasaki Z1B offers excellent handling while remaining stable
The Moriwaki Kawasaki Z1B offers excellent handling while remaining stable

Using the wide handlebars to raise the Moriwaki at the end of the curve allows you to make the best use of the tread of the rear Dunlop and to start the throttle with the meter needle in the 5 / 6,000 rpm zone. We are then rewarded by a dazzling acceleration by the standards of the time while we chain reports to the sound of the howling exhaust. Despite the height of the handlebars, there is no shimmy at the front, even when you change the angle quickly in a fast curve. The bike seems to be really glued to the asphalt as I take it in one go in the triple left, or on the last report in Woodlands. The revised geometry of the frame truly improves handling.

Cycle part

And while the 18-inch vintage Dunlop tires offer good grip despite the narrow rims on which they are fitted, the extra torque provided by the larger bore requires extra care when sliding the rear over large ones accelerations in the triple left.

18-inch Dunlop tires provide excellent grip
18-inch Dunlop tires provide excellent grip

The front suspension is very soft and under-cushioned at the start, until I stop and Gordon adds 10 psi of compressed air to the Kayaba forks to stiffen them. This solved the problem of the nose gear sinking and trying to fold in on the big brakes before Pembrey's very slow hairpins. The large handlebar is very useful here. Adjusting the fork also solved the problem of dribbling which I suffered in faster curves.

Braking

The Moriwaki's brakes were Achilles' heel when Croz drove it, robbing it of its best chance of victory in the TT F1 season in front of the Grand Prix celebrities at Silverstone. It was not the first time that this had happened and although the Lockheed calipers were doing the best they could to stop the bike, I discovered at Pembrey that you have to tighten the lever really, really hard for the brake, because there is no real bite when you grab the lever. In addition, even if it didn't happen to me during the tests, Croz experienced serious braking losses, caused by such heat buildup that the discs were deformed. The culprits are not difficult to find and take the form of the Japanese 296 mm double stainless steel discs mounted on the motorcycle. I find it surprising that Croz didn't solve the problem by simply switching to the Brembo cast discs that all the other drivers used. Used with the same Lockheed calipers as those mounted on the Moriwaki, my P&M ensured braking that was both predictable and effective. As it stands, you must not only brake hard on the 230 mm rear disc so that the Moriwaki slows down correctly in the fourth before the hairpin, but also use a little engine brake. Fortunately, there is no trace of dribbling, although I remain ready to operate the clutch lever if necessary ... did not solve the problem by simply switching to the Brembo cast iron discs that all the other drivers used. Used with the same Lockheed calipers as those mounted on the Moriwaki, my P&M ensured braking that was both predictable and effective. As it stands, you must not only brake hard on the 230 mm rear disc so that the Moriwaki slows down correctly in the fourth before the hairpin, but also use a little engine brake. Fortunately, there is no trace of dribbling, although I remain ready to operate the clutch lever if necessary ... did not solve the problem by simply switching to the Brembo cast iron discs that all the other drivers used. Used with the same Lockheed calipers as those mounted on the Moriwaki, my P&M ensured braking that was both predictable and effective. As it stands, you must not only brake hard on the 230 mm rear disc so that the Moriwaki slows down correctly in the fourth before the hairpin, but also use a little engine brake. Fortunately, there is no trace of dribbling, although I remain ready to operate the clutch lever if necessary ... not only do you have to brake hard on the 230 mm rear disc for the Moriwaki to slow down correctly in the fourth before the hairpin, but also use a little engine brake. Fortunately, there is no trace of dribbling, although I remain ready to operate the clutch lever if necessary ... not only do you have to brake hard on the 230 mm rear disc for the Moriwaki to slow down correctly in the fourth before the hairpin, but also use a little engine brake. Fortunately, there is no trace of dribbling, although I remain ready to operate the clutch lever if necessary ...

The front discs are truly the weak point of the bike
The front discs are truly the weak point of the bike

Conclusion

Mamoru Moriwaki's success in creating the Crosby superbike was to completely resolve the handling problems linked to the original frame, while providing an additional level of performance to the Kawasaki engine thanks to its own parts and cylinder head settings. . If this did not fully allow the bike to have the extension of the Honda, it provided him with sufficient surplus vis-à-vis his private rivals, like me. To this extent, the Moriwaki has indeed played a crucial role in the development of Crosby's career, which is why it holds a special place in his heart. But the key ingredient to reach the top was undoubtedly Graeme's own talent and that's what this glorious piece of

Moriwaki Kawasaki Z1B
Moriwaki Kawasaki Z1B



IMG 2625-748                       bike2-713-713
Croz Moriwaki – The Building Process
 
 The concept of re-producing a working replica of the Crosby Moriwaki TTF1 Monster from 1978/79 period has been an exciting project.
 The main aims were to re-produce an exact as possible copy of this “famous bike” and by using the similar manufacturing techniques as was used 40 years ago.
 The basic chassis is a 1976 model Z1-B so as to take advantage in those days of the regulations for the TTF1 World championship which stated that the maximum carburettor size must be same as the homologated model in this case the 1976 Z1-B being 28mm. The latter model Z900 came out with slightly smaller 26mm size carburettors making it not as desirable. 
By tig welding in strengthening bars in strategic area’s the chassis was made more rigid for racing purposes. A new headstock has been manufactured and fitted to the chassis at a slightly different angle. The triple clamps are designed to give the correct off-set and to work with the new caster angle.  Brackets and non essential tags and brackets have been removed and additional exhaust hanger brackets and other attachment points fitted.
The same period style 800mm Kayaba racing front suspension has been fitted using Moriwaki brake brackets to accommodate the classic AP style period brakes with there steel braided lines. The rear shock units posed a bigger problem as the original Kayaba units are no longer available but a suitable substitute has been found by using Performance works shocks with a very similar appearance.  
Mounted at the back is a Moriwaki steel period swing arm of 500mm in length to house the 4:00 x 18” rear magnesium Campagnolo copy wheel produced by Marvic from their “Classic” range.  The front is a 2:75"x18” Marvic and tires are a Continental ContiGo Attack Classic racing tire. 
Fuel tank is an exact glass replica complete with a dry brake re-fuelling system for authenticity. The fibre glass front guard, seat and bikini fairing have come from exact moulds off the original bike.  
The Z-1 engine has been build from the scratch using all new bearings, seals, valve gear, cams and 1075cc pistons at a nominal 1:25-1 ratio.  It comes with a standard ratio gear box or standard ratio for street use.  A high flow oil cooler has been fitted.
Replicating the look we used an old “Monster exhaust” with some subtle changes. The engine has been built to be ridden but only with enough power (120hp) not to require continuous maintenance. 




IMG 2623-621carb2-316-940rearWheel-132-427

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