Summary
- Kawasaki led the turbocharged bike revolution with the GPz750 Turbo, pushing boundaries with revolutionary know-how and design.
- The distinctive turbo setup lowered lag and optimized efficiency, offering an exhilarating driving expertise for bike lovers.
- Despite some drawbacks, the GPz750 Turbo stays a uncommon and collectible piece of retro-history, showcasing Kawasaki’s engineering prowess.
In the early Nineteen Eighties, with technological developments making the rounds within the bike world, lovers waited eagerly for some ground-breaking know-how to hit the market. That innovation was turbochargers. But simply as shortly because the know-how arrived, it disappeared. The Big Three, comprising Honda, Suzuki, and Yamaha had stopped constructing their 650 cc turbo-based bikes resulting from efficiency points. Their engines have been too small, and the turbocharger was not near the engine, resulting in spool-up time known as turbo lag.
As Honda, Suzuki, and Yamaha left the market, Kawasaki timed its reveal completely and revealed its turbo bike. It would have appeared logical for Kawasaki to tug the plug seeing its counterparts withdrawing from the market. But Kawasaki’s turbocharging roots could be traced again to the late Nineteen Seventies when Alan Masek, then Vice President of Kawasaki Motor Corporation, provided to purchase the Z1 from Kawasaki to collaborate with American Turbo Pac to supply a turbocharged Z1R. Kawasaki gave the go-ahead, although they weren’t instantly concerned within the venture.
ATP removed the Mikuni carburetors and the four-into-two exhaust system for a RayJay turbocharger, collector exhaust, and Bendix accelerator-pump carburetor. The set up was compact and neatly routed. It was their first foray into building turbocharged motorcycles that laid the foundation for future developments. The success of the Z1R/TC was highlighted by drag racing champion Jay Gleason’s outstanding 10.05-second quarter-mile run on a bike from the seventies. It was remarkable, but it surely did encourage Kawasaki to additional discover the potential of turbocharging know-how.
In order to provide the most recent and correct data potential, the info used to compile this text was sourced from Cycle World and https://www.motorcyclespecs.co.za/
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The turbo was totally different from those bought earlier than and was based mostly on a much bigger platform – a 750cc based mostly on the GPZ750 – giving Kawasaki a secure basis to work on. With any turbocharged system, a lift is necessary. However, bike engines in inventory type will not be designed to make use of their authentic compression numbers with a turbo setup resulting from detonation brought on by the overheating of the extra-induced fuel-air combination. Engine compression ratio is lowered when a turbo is added with a management machine put in as a security web known as a lift regulator, which ensures enhance stress going into the engine is regulated and doesn’t exceed a sure stress.
Conventional aspirated motorcycles rely on normal atmospheric pressure for the intake of air whereas turbochargers improve consumption stress above regular atmospheric stress when on enhance. All turbos have two chambers and turbine wheels linked by a standard, sealed shaft. Exhaust from the engine is routed by means of the turbine, spinning the shaft. The compressor is mounted on the opposite finish of the shaft, and, because it spins, incoming air is compressed and compelled by means of the consumption tract. The compressor should attain a sure RPM earlier than it will increase stress; to achieve that RPM, the turbine have to be powered by sufficient exhaust fuel. Reach that RPM and also you’re on enhance. Below that RPM, you’re not having enjoyable.
Engine Specifications
Engine |
Four-stroke, turbocharged, transverse four-cylinder, DOHC, 2 valves per cylinder |
Displacement |
738cc |
Bore x Stroke |
76.0 mm x 55.0 mm |
Max Power |
112 hp @ 9,000 rpm |
Max Torque |
73.1 lb-ft @ 6,500 RPM |
Compression Ratio |
7.8:1 |
Cooling System |
Air-cooled |
Induction |
Mikuni gasoline Injection |
Key Highlights
- Runs a lift of 10.5psi
- Full fairing options an built-in aluminum member to maintain it in place when on enhance
- O-ring ultimate drive chain has particular cut-outs in each different hyperlink to cut back weight and warmth build-up
Hardware And Components
In the iconic GPz750’s case, Kawasaki engineers used low-compression pistons (flat) slightly than domed ones, a cylinder head from a KZ650, and a hardened main chain. This was topped by thinner body tubes, a thicker walled swingarm, totally different cam timing, a bespoke Uni-Trac rear linkage, and a Hitachi HT10-B turbocharger. The turbo changed carburetors for gasoline injection managed by a small microprocessor to watch the electronics. The DFI (Digital Fuel Injection) pc (housed within the tail) used digital sensors to mechanically monitor and alter throttle place based mostly on numerous parameters akin to throttle place, altitude, and temperature. Due to the routing of pipes for the turbocharger and full fairing, the GPz got here out weighing an additional 30 kilos over the usual 750. But it additionally made a further 35 horsepower.
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The turbocharging system employed within the GPz750 Turbo featured a novel design aimed toward lowering lag and optimizing efficiency. By mounting the turbocharger near the engine (on the entrance in entrance of the crankcases) and using quick header pipes, Team Green minimized the space the air traveled earlier than reaching the turbocharger. This design not solely lowered turbo lag, but in addition improved throttle response, leading to higher acceleration and enhanced rideability.
Demonic Speed
11.40 seconds at a terminal velocity of 118.42 miles per hour–those are the figures for the GPz750’s quarter-mile run. The figures don’t appear that spectacular when in comparison with the prototype’s ads throughout testing or the Z1R which was based mostly on a 1000cc platform, but it surely had the thrust to knock you again. The enhance started constructing at 3,500 RPM and because it received previous 4,000 rpm, issues received severe, and above 5,000, the turbo spooled to problem the acceleration of any liter-class bike. As talked about above, due to the turbo being close to the engine, there isn’t a lot lag, both.
And Underpinnings To Match
While the GPz750 Turbo was undoubtedly a technological accomplishment, it was not with out its challenges. The transition from off-boost to on-boost may very well be abrupt, catching riders off guard. Additionally, the bike’s heavy steering and stiff suspension made low-speed maneuvering lower than best. However, the bike’s anti-dive forks had a valve fitting that closes beneath braking and re-routes the fork oil to extend compression damping. The damping was managed by way of a knob that had 4 positions and, surprisingly, the bottom setting on the Turbo corresponded to setting 4 on the usual GPz. This meant the anti-dive labored properly beneath heavy braking.
Speaking of braking, the setup – the rotors, calipers, and grasp cylinder – on the GPz Turbo was straight off the GPz1100. The solely distinction was the scale of the rotors on the Turbo, which measure 11 inches on the entrance and 10.6 inches on the rear – a rise of 1 inch and 0.6 inches on the entrance and rear (respectively) from the usual GPz. The brake traces on the Turbo have been additionally higher, with a stiffer wall and inside Teflon lining to withstand swelling beneath warmth in comparison with standard rubber hoses. They enabled consistent pressure and two-finger braking when not at ridiculous speeds.
Though the Turbo’s body was much like the GPz750 (with relation to the wheelbase, rake, and path), there have been variations in order that it may deal with the elevated forces and acceleration. The tubes have been bigger in diameter with thinner partitions, additionally together with the Turbo’s spine tube, the cross-brace positioned in entrance of the engine, and braces above and beneath the swingarm pivot. There’s additionally a brace behind the steering. The swingarm had a field cross-section with 0.5 mm thicker partitions fabricated from aluminum that pivoted on needle bearings and had eccentric axle adjusters. That mentioned, the wheelbase, although the identical, ought to have been made longer to deal with the elevated energy. That’s as a result of the entrance was all the time within the air beneath heavy acceleration.
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Despite a few of the GPz750 Turbo’s drawbacks, it stays a testomony to Kawasaki’s engineering ingenuity and revolutionary spirit. It is 2 sides of the identical coin; from well-behaved to thrust-back-in-the-seat foolish. Rare and collectible, it’s method forward of its time and totally different from Honda, Yamaha, and Suzuki turbo bikes that used to make use of aftermarket turbos. They weren’t efficient and didn’t have as a lot energy because the Kawasaki. So if you’ll find one, you would personal a bit of retro-history.
Additional Specifications
Ignition |
Digital |
Transmission |
5-speed |
Final Drive |
Sealed chain |
Frame Type |
Tubular body with spine. Reinforced with cross braces |
Front Suspension / Wheel Travel |
37mm air-adjustable forks, adjustable anti-dive / 5.1 inches |
Rear Suspension / Wheel Travel |
Kawasaki Uni-Trak air-adjustable single shock, adjustable for rebound damping / 4.0 inches |
Front Brakes |
2 caliper, 2 x 280 mm rotors |
Rear Brakes |
Single Caliper, 270mm rotor |
Rake / Trail |
24.5° / 4.1 inches |
Dimensions (L x W) |
87.0 in x 29.0 in |
Wheelbase |
59.0 inches |
Seat Height |
31.0 inches |
Ground Clearance |
5.1 inches |
Dry Weight |
492 lbs |
Curb Weight |
531 lbs |
Fuel Tank Capacity |
4.8 US gallons |
Top Speed |
136 mph |