Kawasaki Z Hints
KAWASAKI 900 IS VOTED
BIKE OF THE YEAR
In the annual reader poll conducted by REVS Motorcycle News . Australia's
largest-circulation enthusiast bi -weekly , more than 15 000 votes were received
and the Kawasaki 900 Z1 came out ahead with most votes In a field of 30 other
motorcycles. The newspaper described the Z1’s victory as " sensational" since the
model had been on the Australian market for less than six months . The paper said
that this was most unusual , as it normally takes at least 12 months for a machine to
be accepted by the Australian enthusiasts.
The above extract is from "Kawasaki Cycle World" ( Vol 6 No 2 June 1973)
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900 SECRETS
Neville Koyle, Australian Team Kawasaki tuner, revels the secrets
of the factory supported bike and
what can be passed on that'll work for the faster street 900s.
Definitely the best feature of Kawasaki’s ultra successful Z1 900 is that the very first model is much the same as the 76 specification. No weaknesses have been found and apart from detail , cosmetic and fashion changes the basic machine remains near identical in its fourth year.
The original design has proven to be strong and lend itself to all kinds of racing competition from drag bikes to sidecars. It has won the last three Castrol 6 hour races with the 75 award going to Team Kawasaki’s bike that has raced at the Calder 2 hour , Castrol 6 hour , Queensland 1 hour , with out even any appreciable chain wear !!
Like all powerful bikes, there are many fallacies on how to extract more horses and more speed. Even though the basic package is good , it can be improved to handle better, stop quick and maintain top speed longer.
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STEERING
Both wheels should be removed, the rims trued and then accurately balanced. On assembly, the wheel alignment is crucial. Ignore the swingarm marks and set the back spindle by sighting a length of string along both wheels. If wobbling persists then the trouble is almost sure to be steering head bearings . Faults wont show up by the old tug test and they should be replaced by new, and correctly tensioned . Sometimes even new bikes benefit by replace steering races property fitted!
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OIL
If you’re a leisurely touring man then an ordinary Super 20 - 50 grade is sufficient. Any more calls for a specialist oil such as BP Coarse Plus. Never overfill as excess oil will inevitably find its way through the breather system into the air filters and enrich the mixture . Keep the level between the two marks on the sight window. An interesting little sidenote is a warning not to use GTX in an H2 gearbox, hard riding will see clutch slip problems.
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CAMCHAIN
This is frequently overlooked by many enthusiasts. The chain must be set to the correct tension not only to prevent damaging "whip " but also to maintain correct valve timing. Correct tensioning sequence is :-
1. loosen lock nut and lock screw.
2.turn the engine till the static marks line up.
3. turn the engine forward by two full turns and HOLD in position.
5.lock.
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WEAR
To keep the engine going as long as possible adopt the following rules:-
1.after starting the motor let it warm up with a small amount of choke. Further warming at running speeds is necessary before top revs are applied.
2.use the best oil and change it regularly. Economy in this department is crazy
3.if you are not capable of setting the running adjustments spot on then pay some one who can . Its cheaper in the long run.
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REAR CHAIN
Would you believe that last years Castrol 6 Hour winner started the race with 1" chain slack and finished with only 1 1/2 " , and further more the same chain has raced the Calder 2 Hour , Castrol 6 Hour , Queensland 1 Hour and is still OK ?. It is of course a 75 spec self lubricating chain as currently fitted to new bikes . Older models should have the oil pump removed together with the old chain and $75 invested in a new one. A very wise buy.
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LIGHTS
A fault which few people appreciate is that most globe failures are caused buy the high frequency vibration put out by the Z1 engine. This can not only demand that standard globes are replace from time to time but also that non standard items brake down with expensive rapidity.
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CARB PIPES
A common mistake made by too many owners is to quickly replace the petrol tank and confuse the fuel lines with the carb breather pipes . The result is an engine that runs rough and floods. This has been cured by the latest model having pipes of different diameters that cannot be mistaken.
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VALVE CLEARANCE
Believe it or not but experience has shown that these are not absolutely critical . By this we don’t mean they can be let go to ridiculous limits , its just that they seem to have more safety margin than other running adjustments. Don’t let them become too tight though ; they seldom loosen.
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REAR DRUM
Understand that the 900’s rear drum is good enough for 20 hours flat out racing and has been praised by most top riders. "So don’t go complaining that Kawasaki should have fitted a rear disc long ago. All that is required to stop any grabbing and increase sensitivity is to increase the taper on the leading lining from 1/4" to 5/8" with the angle going right down to the shoe.
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REAR UNITS
If your original damper units aren’t worn then fitting Boge Mullholland or Koni shockers will not improve the bikes handling . The major problem here is often adjustment. For a person of average weight road riding means number 2 position and racing calls for either 4or 5 depending on the track.
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CARBS
Should a motor have a flat spot between 5 to 6,000 rpm then raising the needles by one notch each should cure it . Another common fault is rough running caused by hair or fluff in the emulsion tube above the main jet. Don’t go playing with the carburetor settings unless you are sure of what you are doing .
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SPARK PLUG
Providing these are in good condition correctly gapped and of the recommended heat range then there is no real difference between Bosch or NGK or whatever. The Team racing bikes run on either Champion N57G or N55G as per the racing Yamaha two strokes. In the Six Hour , N55G was chosen.
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SWING ARM
We’ve already said don’t trust the spindle adjustment marking so there’s no need to repeat why. Earlier 900’s were fitted with fibre swing arm bushes that had built in thrust washer faces. The latter broke off allowing the bush ( now without a retaining flange ) to move inwards so causing rear wheel wobble. Replacement with new is the only answer.
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VALVE SPRINGS
The 900 motor is good for a sustained 10,000 rpm with complete reliability. Best racing speeds are between 7 to 10,000 rpm , as was used by the winning 6 Hour bike. Increasing valve spring tension will do nothing to improve the engine.
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ROTOR
These can literally blow up if allowed to deteriorate. The steel insert in the alloy that has the 3 studs to the start clutch can work loose . If a gap develops between the steel and alloy then the rotor must be replaced. Engines that are continually revved high should have this point checked regularly. Take this seriously as the damage at 10,000 can be dangerous as well as wickedly expensive.
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FRONT DISC
If you afford it convert to a dual disc set up . The cost is high as the right assembly and the master cylinder is required. This definitely gives better feed back and demands less hand pressure to gain more control.
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GROUND CLEARANCE
The first things that scrape are the foot pegs . Next is the centre stand extension. By that time the bike is being leaned over a long long way and going further till the alternator cover grinds merely proves it is probably being ridden incorrectly. Greg Hansford only hits the alternator cover when circulating Amaroo at under the old lap record!.
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IGNITION
Timing is crucial . It must be very accurately set . Approximate is just not good enough. First of all the points should be cleaned or replaced and set to 14 thou. Then with a circuit meter (or even thin paper) set their breaking to roughly coincide with the static timing marks. NEVER advance the engine , if it must be set crudely then go for retardation . But don’t let this fluctuate more than a degree , the thickness of the timing line ! As strobe is the only way to set it correctly . The inter points relationship is vital., BOTH must be on the same mark and spot on. Exhaust pies don’t blue when the timing is correct.
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CLUTCH
Fortunately the clutch fitted to the 900 has proven very strong and trouble free, Its setting isn’t crucial.
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FORKS
Little wants doing here. There’s no point in going further than refilling with the correct quantity of A.T.F. ( automatic transmission fluid).
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HOTTING
If you’re hell bent on spending money on an otherwise perfectly satisfactory machine then think along these lines :
1.an alloy cooler , If the engine is continually belted in a hot climate then this is a necessity ,. Take it seriously.
2. 4 into 1 exhaust systems can improve overall performance ( sometimes they don’t make any difference at all ) if the jets etc., are tuned in to suit. To do the job properly the cams etc,. should also be modified as the pipes on their own aren’t sufficient .
3. POWER . This can be obtained by competent engineers only. The carbs should be bored out 2mm and up jetted , the cams modified for more dwell and lift (20 degrees and 25 respectively ) and stelite topped valves fitted (providing they are accurately ground to the correct length to main clearances) . A big bore kit is also required.
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