The Z650 was one or the bikes that helped build up the Kawasaki reputation for powerful, bullet-proof fours; a reputation on which they are still trading. When it came out in 1977 it was faster than most 750s and proved astonishingly strong and reliable.

It was the first of a new generation of engines. The DOHC unit used a one-piece forged crank and plain bearings rather than the built-up, ball and roller systems of the earlier Z900s and Z1000s. The gearbox was so tough that the McLaren Grand Prix team tested one and were impressed by its level of engineering, and it was quite capable of surviving a major blow-up upstairs.

The bike didn't change much throughout its production run, so it stayed reasonably priced and useable, as well as offering a host of interchangeable parts.

It handled reasonably well, although the rear shocks were a weak spot and later models stopped well thanks to the first use of sintered pad material.

Over a decade after its launch, we are still seeing the direct result of this bike, in the guise of the GPzs and Ninjas, all built on the bedrock of the Z650.

Four basic types of 650 were imported into the UK: B, C, D and F. The B1 arrived in 1977 while the other three types were available concurrently from 1980 to '82. Most of the changes were cosmetic rather than mechanical as the engine

remained basically the same from the hi up to the last F4 of 1983.

The B1 came in Candy Super Red or Candy Emerald Green, with the B2 in Luminous Dark Blue or Luminous Burnt Red. The B2 had revised caliper position behind the fork leg modified carbs, different generator and brake master cylinder, diaphragm fuel tap, hazard lights and needle bearings in the swingarm.

Models up to engine number KZ650BE 092001 used single-plate camchains but after that they went over to Hy-Vos.

The Z650C came in Moon Dust Silver or Metallic Regal Blue, and was smart and improved. Twin discs went on to alloy wheels on uprated front forks, while heavier flywheels went inside polished crankcases. Only the C2 and C3 came to England, with engine numbers between KZ650BE 043950 and 092001 (note camchain comments above).

In 1980 came the unmistakable D, better known as the SR, with its custom styling, and crossover pipes, which Kawasaki claimed improved torque.

One innovation on it was the first use of sintered brake pads to try to combat wet-weather lag.

In "81 they fixed a weak spot and fitted electronic ignition. This practical step was negated somewhat on the F model {engine number KZ650BE 128901 onwards) by the Japanese disease of tarting the bike up beyond good taste.

Any model you find now will probably have a pretty high mileage and, while they can take it. it is worth changing a tew items just lor peace or mind. Oil pumps, for example, should be changed after 40,000 miles along with the pressure release valve.

The primary chain goes at about 50,000 miles and can get quite noisy. The clutch drive cush rubbers tend to harden after a while as well. The camchains, if of the single-plate type, might last over 60,000 miles (eat your hearts out, Honda) but the later Hy-Vos tend to go at about half that distance.

Coils can give trouble as they are just above the cam covers and tend to pick up a lot of road muck. If dirt gets in or the connections get sloppy the bike tends to run on two pots. Old starter motors sometimes give up, but weak and corroded connections throughout the bike can cause tedious problems, that are hard to diagnose.

Pre-electronic ignition models would be much improved by the installation of same.