The Kawasaki Gpz305 was a 306 cc (18.7 cu in) twin cylinder air-cooled SOHC four-stroke motorcycle, produced in 1983 to 1994 by Kawasaki in Japan. The model evolved from the earlier ER250 model and used an overbored 61 mm × 52.4 mm (2.40 in × 2.06 in) version of the 249 cc engine first produced in 1979. Kawasaki gave this model the "Gpz" nomenclature to add to its expanding air-cooled sports bike range, and was marketed as a sports machine. It originally had chain final drive but in 1983 it had a new Kevlar belt final drive first seen on Kawasaki's American styled cruisers.

Kawasaki Gpz305
ManufacturerKawasaki
Production1983–1994
ClassRoadster or sport bike
Engine306 cc (18.7 cu in) SOHC four stroke parallel twin
Bore / stroke61 mm × 52.4 mm (2.40 in × 2.06 in)
Compression ratio9.7:1
Top speed158 km/h (98 mph)[1]
Power26 kW (35 bhp) @ 10,000 rpm (claimed)[1]
Torque25.5 N⋅m (18.8 lb⋅ft) @ 8,500 rpm (claimed)[1]
Ignition typeMagneto CDI
TransmissionWet clutch, 6-speed, belt drive
SuspensionFront: telescopic fork 150 mm (5.9 in) travel
Rear: swingarm 130 mm (5.1 in) travel
BrakesFront: 260 mm (10.2 in) disc
Rear: 160 mm (6.3 in) drum
TiresFront: 90/90-18 Dunlop F8
Rear: 110/90-18 Dunlop K130
Rake, trail26.5°, 94 mm (3.7 in)
Wheelbase1,355 mm (53.3 in)
DimensionsL: 2,130 mm (84 in)
W: 745 mm (29.3 in)
H: 1,185 mm (46.7 in)
Seat height780 mm (30.8 in)
Weight160.64 kg (354.15 lb)[1][2] (wet)
Fuel capacity16.5 L (3.6 imp gal; 4.4 US gal)
Oil capacity1,800 ml (1.9 US qt)
Fuel consumption3.0 L/100 km; 95 mpg‑imp (79 mpg‑US)[1]

It was available with a 250 cc engine as the Kawasaki Scorpion, but came in a different colour scheme.

In Cycle World's "Ten Best Bikes of 1983", the Gpz305 won best "Under 460 cc Street" motorcycle, because it was the "best of the lightweight roadsters", combining small bike advantages of low weight and low cost with the fun of a sport bike.[3] In their review, Cycle World praised the bike's quick handling in comparison with heavier, more powerful motorcycles, saying that the while 1,100 and 750 cc (67 and 46 cu in) displacement bikes have a much greater engine power advantage, they typically have 60 in (1,500 mm) wheelbases, giving the 55.2 in (1,400 mm) wheelbase Gpz305 an advantage in the ease that it leans into a turn.[1] They also said that while large engines have the advantage of having a wide power band and do not need frequent shifting during casual riding, the Gpz305's lack of power below 7,000 rpm forces the rider to shift frequently to get the most out of the bike, making it more fun to ride.[1] The review said the Gpz305's air-fuel ratio was excessively lean in order to meet EPA emissions requirements, which meant the bike took 10 mi (16 km) of riding to warm up enough to run smoothly without using the choke, and that the bike benefited greatly from re-jetting the carburetor, without losing fuel economy in the process.[1]

Notes edit

  1. ^ a b c d e f g h "Kawasaki GPz305", Cycle World, CBS Publishing  – via Bondi Digital Publishing (subscription required) , pp. 72–76, November 1983
  2. ^ Tank half full weight is 342 lb. and capacity is 4.0 US gal, so with a weight of 6.073 lbs per US gallon wet weight is 342 + (6.073 * 4.0 ÷ 2) = 354.15 lb. Bell Fuels. "Lead-Free gasoline Material Safety Data Sheet". NOAA. Archived from the original on 20 August 2002. Retrieved 6 July 2008.
  3. ^ "The Ten Best Bikes of 1983", Cycle World, CBS Publishing  – via Bondi Digital Publishing (subscription required) , p. 35, November 1983