Alternator fixing bolt

[jacobmarley]

I recently read an article in an old bike mag that said on a Z1 check the alternator bolt on the end of the crankshaft every 12 months as it can cause severe damage if it comes loose. After the inaccuracy of the manual on cam torques I thought I would check on alternator bolt torques before I do it ( Manual says 95 ft lbs). What does everyone think?
I have a 1979 KZ1000 shaft, are there any tricky bits to doing this job on a shaft. - Regards Jacobmarley

[Rich]

95 is right, the only tricky bit is holding the rotor whilst tightening, make yourself a holding tool for it, don't screw the screws in too tight or you will knacker the magnets.

[Pigford]

Use a bit of strap (that nylon 'tie down' stuff) to wrap tightly around the rotor, then attach to the footpeg mount or similar secure item on the bike.
As you tighten (or loosen even) the bolt, the strapping grips the rotor tighter & will not damage it
Works everytime

[Keefleaf]

When replacing altnenator magnet,it`s worth a little grinding paste to get the taper 100%.A little dab of paste on taper,thenslide magnet on and
grind/lap left to right motion.Remove rotate 180degrees and repeat.
similar to grinding in valves....old Nortons never had woodruf keys ,
they relied on this tight taper fit. Key in place ,slide magnet on.I`ve used
oil filter wrench to hold in place while doing up nut,a little locktight might help.
added note ;top yoke center bolt doubles as extracter.take it out ,turn it into magnet center until it bottoms out on crank,hit with mallet.tighten bolt,wack again,repeat until it "pops off". good luck.

[jacobmarley]

Got around to doing the job today, the webbing strap trick worked great - thanks Pigford - Jacobmarley

[ChrisB]

Thanks for the tip Pigford, just done the same thing with my new project.
The tapers in the rotor and on the crankshaft have damage and when bolted up, the rotor has a slight wobble which is enough to stop the starter motor spinning the engine. Measured the run out with a DTI and found this to be 0.03mm on the bearing face of the starter gear, and 0.13 at the outer end of the taper suggesting previous crash damage. Any suggestions for a fix which doesn't involve having the crank out, very much appreciated!!!