Last 2008 Kawasaki implemented a number of tweaks and updates to the 14 aimed at improving low-end power, but the new model was given a head-to-toe going over for 2012. Although the land rocket of a sportbike retains a familiar look while gaining the R designation, below the surface the biggest of the Ninjas received its most comprehensive revision since its 2006 debut.
Headlining changes are a host of revisions for the big inline-Four powerplant, along with two firsts for the ZX-14: Kawasaki’s traction control system (KTRC) and a slipper clutch.
Leading off engine updates is a 4.0mm increase in stroke, from 61.0 to 65.0mm, while the 85mm bore remains unchanged. The ZX’s previous 1352cc was a class-leading displacement figure, but with the new 85.0mm x 65.0mm bore and stroke the 14 ensures its place as displacement king with 1441cc. Compression is also up, from 12.0:1 to 12.3:1.
Combustion chamber shapes were optimized for 2012, and they’re now surface-milled now rather than cast. Intake ports are reshaped and polished for improved flow, and new, longer intake valves have better durability, according to Kawasaki.
New camshafts have increased lift and revised profiles, while a stronger cam chain and revised tensioning system have improved reliability. Newly designed forged pistons with thinner crowns are lighter, and like many of the engine components, offer increased durability. The new pistons (paired to stronger connecting rods) are cooled by a new oil-jet cooling system that pumps a continuous stream of lubricant at the underside of each piston. Kawasaki says testing shows the engine runs considerably cooler with this piston cooling system.
Crankshaft main journals are thicker, from 38 to 40mm, and the engine’s dual gear-driven counter balancers have revised balance weights to help mitigate vibes in the longer-stroke engine.
A new air-cleaner element is larger and thicker, with 10% more surface area and 40% more airflow capability, allowing better breathing for the revised fuel injection system. The exhaust system is essentially all-new with reshaped, larger-diameter tapered header pipes, and larger-volume, reshaped mufflers each house a catalyzer.
Manufacturers aren’t always willing to divulge horsepower ratings, and this time is no different, but we can safely speculate crankshaft power above 200 ponies. The previous model claimed 190 hp at the crank with peak torqe at 113.5 ft-lbs at 7500 rpm. The last time Motorcycle.com dyno tested the 14, the big ZX produced 159.5 hp at 9550 rpm and 99 ft-lbs at 7800 rpm.
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