1978 Z650-B2/B2A

Very few differences were made to the B2. The front brake caliper was reversed to the back of the fork leg and the front master cylinder reservoir was changed from a round item to a trapezoidal one. The charging system was changed from a three-phase system to a two phase and the regulator and rectifier were now combined in a single unit. A hazard switch was added to the left-hand switchgear. Needle roller bearings were now used in the swingarm instead of the previous model's plain bushings and slight modifications were made to the carbs to improve low speed operation. The manual operation fuel tap was replaced with an "automatic" diaphragm type unit. There were also some slight detail changes to the outer engine cases to incorporate the new lower case Kawasaki logo. The front forks were slightly modified. The B2A was a US-only model with 22mm carburators, as opposed to the 24mm items fitted to units sold elsewhere. Power output was reduced to 60 hp (SAE net at the crankshaft) at 8,000 . This change was probably due to emission requirements in the US market. All other aspects and equipment of the B2A construction were identical to the B2 models sold outside the US.

Both the B2 and B2A received the four way hazard flashers that had been previously installed only on the C1.

1978 Z650-C2

KZ650C2 All stock and original except for tires, engine guards and turn signals

The motor was, again, a standard B2 unit but the C2 carried on with mechanicals the same as were found on the C1: seven spoke alloy wheels with twin discs up front and a disc at the rear. The revised graphics (compared to the C1) made this model stand out from the crowd and the C2 was a very good seller. The first batch of bikes in the UK came with a free colour matched helmet. This model was only offered in certain markets so may not have been available in your particular country.

1978 KZ650-D1/D1A

This was actually the first "SR" model released. The D1 may have been sold only in Japan but this is unknown. It featured a lot of the equipment from the C model but with a different frame, the substitution of a 16-inch rear wheel, deletion of the tailpiece (which was such a trademark of the B/C models) and an entirely different seat with a "tuck and roll" appearance to give it the full-on "chopper" look. As well, the fuel tank shape was completely different from the B/C models and more in keeping with the "chopper" look. As well, the D model featured rubber mounted two bolt style footpegs. All other models used a single bolt rigid style peg setup until the 1979 models. All D models also included a "Low Fuel" warning light incorporated into the tachometer faceplate.

The D1A was a US-only model with 22 mm carburetors, as opposed to the 24 mm items fitted to units sold elsewhere. Power output was reduced to 58HP (SAE net at the crankshaft) at 8,000 RPM . This change was probably due to emission requirements in the US market. All other aspects and equipment of the D1A construction were identical to the D1 models sold outside the US.

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 few items just for 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.

Earlier models seem to have been a little faster, but many parts are interchangeable. One point to remember if buying an older B model is that there is only one bearing size available, so if the big ends go it means a new crank. Later models had a choice of bearing shells.