Buyer’s guide

Practical Sportsbikes (UK) - - Contents -

The mighty Kawasaki Z900/Z1 in all its storm­ing glory

Electrics

It’s a typ­i­cal early ’70s sys­tem, ei­ther not charg­ing, or over­charg­ing and boil­ing the bat­tery. Most bikes will be fixed with a new reg/rec by now. Most peo­ple keep the old stuff when they fit a mod­ern unit – orig­i­nal­ity is worth money.

In­stru­ments

Nip­pon Denso stuff was the best around back then. The nee­dles lose their damp­ing af­ter time and fluc­tu­ate madly, and the red paint fades. But at £90 for a re­build, or £75 for repli­cas, this is not an ex­pen­sive fix.

Steer­ing head

Many be­lieve the weavy high-speed han­dling is down to old cup and ball head­stock tech. Not so. Dave Mars­den: “The only ben­e­fit of ta­per rollers is so you don’t have to mess with 39 ball bear­ings if you do the yokes.”

Forks

Soft with an­tique damp­ing as­sem­bly. Bet­ter brakes only make things worse. There’s not much you can do ex­cept fit springs prop­erly matched to your weight and then mess about with damp­ing oil quan­tity and vis­cos­ity.

Brakes

Back in the ’70s noth­ing on two or four wheels had any­thing like de­cent brakes, so the sin­gle-pis­ton, sin­gle disc set-up was OK. Fit­ting a sec­ond disc and caliper (a UK op­tion) makes a huge dif­fer­ence. Z-power does a kit for £400 all-in.

En­gine

Nu­clear Ar­maged­don-proof. Of­ten they don’t even need a re­bore af­ter huge mileages. The only things that wear are the cam­chain ten­sioner blades and any other rub­ber com­po­nents blighted by age, ie valve guide seals.

Gear­box

A very old, abused gear­box might jump out of sec­ond be­cause ei­ther the dogs or the se­lec­tor forks are worn. If the chain has been run too tight, the out­put shaft bear­ing can give up – a cases apart job to re­pair.

Car­bu­ret­tors

Gen­eral wear, sloppy link­ages and air leaks can all cause is­sues. Some rid­ers com­plain of a flat-spot off tick­over. Raise the tick­over up from 1200 to 1700rpm to mask the is­sue. Bet­ter still, fit new Kei­hin CR carbs.

Swingarm

It flexes and that’s where the ‘in­ter­est­ing’ han­dling is born. Strength­en­ing gus­sets and seams are the an­swer to main­tain the al­limpor­tant orig­i­nal look. Bet­ter shocks help, with pat­tern OES at £90 a pair.

Cy­cle parts

Replica 4-4 and 4-2 sys­tems are avail­able. Ready­painted body sets are avail­able for a modest £1300. Seats, again from Ja­pan, are off the shelf items. Huge pop­u­lar­ity of the model helps keeps

costs down.

Check out the twin disc con­ver­sion op­tion

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