Kawasaki Z1: The 1970s Superbike

Is a Kawasaki Z1 the right bike for you?

Kawasaki Z1B

Original, unrestored Kawasaki Z1B – needs a lot of TLC to keep it in this condition.

Photo Courtesy Veloce Publishing

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The Essential Buyer's Guide: Kawasaki Z1 & Z900 (Veloce Publishing, 2013) by Dave Orritt is packed with good advice on choosing the right Kawasaki. Covering the Z1, Z1A, Z1B, Z900 and KZ900 from 1972 to 1976, this book features a comprehensive inspection guide and in-depth analysis of strengths and weaknesses. The following excerpt from section 3, “Living with a Kawasaki Z1” details the features of the 1970s superbike.

You can purchase this book from the Motorcycle Classics store: The Essential Buyer’s Guide: Kawasaki Z1 & Z900.

Living with a Kawasaki Z1 – Will you get along together?

From the start of Z1 ownership it is important to realise that the bike is a 1970s ‘superbike.’ In the 1970s the Z1 completely changed everyone’s perception of motorcycling. It gave unheard-of performance with a massive 903cc double overhead camshaft engine, 130mph top speed, four carburettors, 82bhp, and a sensational four-into-four exhaust system. Added benefits were electric starting, disc brake stopping power, and day-to-day reliability.

Modern bikes are largely maintenance free, except for routine chain adjustment and oil level checks. Owning a Z1 in the 21st century can also offer reliable motorcycling, but most Z1 owners will not use their bikes for commuting, but as a second or third bike to take out on good days to classic bike meets or shows.

Maintenance on all models is relatively straightforward. All models have the same engine configuration, and all are 903cc displacement as standard.

The 1972/73 Z1 is the original model, and was produced with a blackpainted engine. Kawasaki had problems with the durability of the paint on the crank cases, cylinder block and cylinder head. The subsequent 1974, 1975 and 1976 models were produced with the silver alloy finish to overcome the earlier problems.

Due to the power of the 903cc engine, the chain technology at the time was pushed to the limit and was helped by the fitting of a chain oiler mechanism. This plastic oil bottle and pump arrangement provided constant lubrication to aid chain life. The 1972/73 Z1 and the 1974 Z1A models had these oilers fitted as standard. By 1975, chain technology had moved on, and the1975 Z1B model was fitted with the new ‘o-ring’ chain technology, and Kawasaki omitted the oiler from this model.

Carburation on all Z1, Z1A and Z1B models was provided by 28mm Mikuni carburettors, giving the engine 82bhp. For improved performance, revised 28mm Mikuni carburettors were fitted to the Z1A model from approximately frame number Z1F32500 and for all of the Z1B model range. By the release of the Z900 (KZ900) model, emission laws had changed, so revised smaller 26mm Mikuni carburettors were used. This resulted in a drop in power to 80bhp, but better driveability.

Exhaust style did not change throughout the 1972-1976 period, but the Z1, Z1A, and Z1B models had fewer restrictive baffles to produce more power with the larger carburettors. For the 1976 Z900 (KZ900) model, more restrictive baffles were fitted to the exhausts, stamped with a ‘76’ marking to identify the emissions law changes.

Living with a Z1 can be even easier with modern technology. Many owners fit electronic ignition systems to eliminate the problems associated with contact breaker points. High-performance, cleanable air filters and modern oils help hot running. Tyres are now available in modern softer compounds for better road holding, and modern brake pads/brake shoes and braided brake hoses improve the standard performance.

This excerpt has been reprinted with permission fromby Dave Orritt and published by Veloce Publishing, 2013. Buy this book in our store: The Essential Buyer’s Guide: Kawasaki Z1 & Z900