Read instructions before
This operation can be the
most difficult of any carried out on a JAWA CZ engine and you should follow
these instructions carefully or risk damage to the crankshaft and the
removal tool. Consult your manual and a qualified motorcycle engineer if in
doubt. Wear safety glasses as metals splinters may fly off the tool or the
|Remove the primary drive
chain – it does not need to be split. By removing the bush in the
centre of the clutch there is sufficient slack in the chain to
remove it from the drive teeth. Reassembly is the same in reverse.
Fit the chain and then insert the clutch sleeve.
The primary gear sprocket is a simple
taper fit on the shaft. There is no keyway or splines. A taper can
produce one of the strongest bonds and can prove difficult or even
impossible to break.
Worst case scenario you
split the gear using an angle grinder making sure you do not damage the
Heat on the gear might help
but releasing fluid is a waste of time as it cannot run into the taper fit
due to the close tolerances.
Loosen and remove the
retaining nut for the gear.
Fit the special puller on
to the collar on the gear and gently wind in the centre bolt ensuring the
“pull” will be directly along the line of the shaft. When finger tight
use a spanner to take out all slack and then:
Tighten the centre bolt by
one quarter turn.
not try to wind up the centre bolt of
the puller or you will break the puller or damage the end of the crankshaft.
Hit the head of the centre
bolt with the heaviest hammer you have. The gear may simply pop off.
If not turn the puller
centre bolt ¼ turn tighter and whack it very hard again.
The idea is that the impact
jars the gear free of the taper.
If this fails remove the
puller and replace the nut on the end of the crankshaft so it is flush with
the end of the shaft. That ensures that when you try the above process again
the shaft is not damaged.
The process is to keep
tightening the puller centre bolt by ¼ turn between each whack. You will
know when you are getting to the limit as the centre bolt will become
increasingly hard to turn the extra ¼.
If you get to 1 and ½
turns and the gear remains in place consider heating shaft with blowlamp and
whacking it again.
There is no exact science
– one member once said you need a thumpometer! Just bash the head of the
centre bolt as hard as you can.
JAWA CZ Owners Club accepts no
liability arising from providing this advice.
If you do not accept this, do not use this
By Pete Edwards
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10 October 2016 - Privacy
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