History of the Kawasaki GPz305

History of the GPz305

The GPz305 is a follow up of the 1979 Z250. This bike was also in that year a rather powerful machine with a engine of 27 hp @ 10,000 rpm. An unto 306cc enlarged version was used to driven a little chopper in 1981. This model was good for 30hp @ 9000 rpm. A few years later the GPz series arrived. This model line concerns a 250cc engine of 33hp @ 10.500 rpm and a 306cc engine with 36hp @ 10.000 rpm. In Holland the 306 model chopper was favourite as the first bike after the new owned driverlicense. I've never seen the 250 model around here and the 305 GPz was not must sold, due to its high price. In Germany it became a popular machine, because it fitted perfect in the 27hp insurance class. The GPz305 was well known for its high performance and its low petrol consumption. Commonly a 30hp was measured at the back wheel and fuel consumption was around 3.4 liter/100km. Not bad, keeping in mind the conventional 2 valve air-cooled construction. Remarkable for all models are the big 32mm carburettors
Technical updates
The Z250 was build with either cast and wire-spoke wheels. The cast wheels were provided with discbrakes and the spoke wheels with drums. The chaindrive was replaced by a belt in 1985. The GPz series came on the market with the Unitrack suspension, instead of the stereo swing.
Also the engine was several times updated. The camshaft chain tensioner changed from hand to automatic tightened. The clutch became another control mechanism and the rollercamshaft chain was replaced by a Morse (teeth) type. The ignition started with points and ended with an electronic unit. The single fase alternator was replaced for a three fase one. The higher performance of the GPz models was achieved by a sharper camshaft.

Technical Data GPz305

Displacement 306 cm3
Power 36 hp @ 10.000 rpm
Torque 25,5 Nm @ 8.500 rpm
Compression 1:9,7
Topspeed +/- 170 km/h
Weight 147 kg
Gears 6
Fuel capacity 17 litre
Ignition CDI
Engine oil 1,8 litre SAE 10W-40
Accumulator 12 volt 9AH
Fuel consumption3.4 litre

Brave Harry on his moped.

A 100,000km? Possible, but not without some serious work at the engine.

Tips and trics.
pic hammer

The Sound! (Honda six) 106 kB

Honda 250cc six cylinder
From Castrol historical racing tapes


The kawasaki LTD305 (Dutch)
Lothi and the GPz305 (German)
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