kz 900 alternator rotor end crank shaft taper.

i have a 1976 kz 900. the bolt that holds the rotor on the crank shaft came loose and sheered the woodruf key for the rotor. i also found damage to the starter clutch, small and large thrust bushings and the bearing from the crankshaft to starter clutch twisted and trashed. that bearing looks like a large version of a smal end rod bearing. i have a 1980 kz 1000 engine that i have pulled all of the parts off of to get the 900 going again. i was able to get the remains of the woodruf key out of the crank easily with a pick. there was no apparant damage to the crank or taper unusually. after cleaning up the pieces, lubeing them and begining installation i ran into a problem. i used the bolt from the 1000, both were the same, and as i was torqueing it it felt like there was no contact and the bolt finally broke. the manual i have says that the bolt should go to 116 foot pounds. after removing the broken remains of the bolt from the crank i found a stronger bolt of same thread and pitch and tryed a beam type torque wrench, i could only get to about 55 foot pounds before it started to feel like the bolt was starting to stretch. all of the bushings are in place, the rubber damper seems ok, the woodruf key is in the crank correctly. kind of at a loss right now with this. your thoughts and ideas would be greatly appreciated. i used the rotor and clutch assembly from the 1000, starter pinion gear from the 1000. the only thing from the 900 on that side of the engine is the crank and sidecover.

Make sure you're reading the manual correctly.

My manual says;

"Apply loctite to the rotor mounting bolt before istallation, and tighten the bolt with 18 ft-lbs (2.5 kg-M) torque."

Also make sure the thick shim that goes against the crank has the "chamfer" side toward the crank.

Buzz

Hello, Marc, and WELCOME to KZR!
We're glad you're here!

Here's some info from another thread that might possibly be helpful.

Make sure the bolt is in good condition and has not stretched.
Make sure the threads on the both the bolt and the crank are clean - if you have any debris in the crank thread, you may be torquing against the debris rather than tightening the rotor.

...also, make sure the cast aluminum part of the rotor has not started to pull away from the hex steel center. If you have any sign of play / crack, replace the rotor.

Good Luck!

He will need to "Adress" the differences between the 1976 Crank, and the 1980 Crank before coming to a proper solution here.

hello and thank you for your replys. i have checked the fat bushing, it is installed correctly. i have a brand new bolt that is stronger than the original. the rotor looks like it is in good condition. im not exactly sure how to go about checking for the differences between the two crank tapers though. do they make a gauge for this? i still need to get to my manual to recheck the torque value. i just checked the manual that i have, it states to take the bolt to 116 ft lbs. although, it turns out that it is a manual for a 1983kz 1100. the rotor looks different and it doesnt give any size specs for the bolt so it is possible that the 83 uses a larger bolt but im not sure. i know this is confusing but thanks for all of your help. as always, any thoughts and suggestions are welcome, marc...

benjamin wrote:

i have a 1976 kz 900. the bolt that holds the rotor on the crank shaft came loose and sheered the woodruf key for the rotor. i also found damage to the starter clutch, small and large thrust bushings and the bearing from the crankshaft to starter clutch twisted and trashed. that bearing looks like a large version of a smal end rod bearing. i have a 1980 kz 1000 engine that i have pulled all of the parts off of to get the 900 going again. i was able to get the remains of the woodruf key out of the crank easily with a pick. there was no apparant damage to the crank or taper unusually. after cleaning up the pieces, lubeing them and begining installation i ran into a problem. i used the bolt from the 1000, both were the same, and as i was torqueing it it felt like there was no contact and the bolt finally broke. the manual i have says that the bolt should go to 116 foot pounds. after removing the broken remains of the bolt from the crank i found a stronger bolt of same thread and pitch and tryed a beam type torque wrench, i could only get to about 55 foot pounds before it started to feel like the bolt was starting to stretch. all of the bushings are in place, the rubber damper seems ok, the woodruf key is in the crank correctly. kind of at a loss right now with this. your thoughts and ideas would be greatly appreciated. i used the rotor and clutch assembly from the 1000, starter pinion gear from the 1000. the only thing from the 900 on that side of the engine is the crank and sidecover.

the manual i have says that the bolt should go to 116 foot pounds.

The FSM for Z1~KZ900 specifies Loctite and 18 ft-lbs . That's "eighteen" ft-lbs.

1977 KZ1000 is 16.5~19.5 ft-lbs (with Loctite).

1978 KZ1000 increased to 51~54 ft-lbs (No loctite).

1979 KZ1000 increased to 94 ft-lbs (No Loctite).

Good Luck!

My 1976 KZ900A Kawasaki Factory Service Manual specifies Loctite and 18 ft-lbs.

Ok and what are the differences between these two Rotor Assemblies?

thanks to all who expressed their thoughts and ideas. i believe it was a simple stupid mistake. i was using the wrong manual for the job. as posted earlier, i looked up the correct torque value and it was 18 ft lbs. thanks you guys. by the way, the latest post shows two different style rotors, one appears to be a "male" and one is a "female" style in terms of how it rotates inside or outside of the stator. thanks again, now i can move on to the nest step of the project. anybody have or seen a four pin ignition switch for the 76 kz 900. everybody wants to sell me a six pin. i have a six pin but it doesnt excite all of the terminals for all electrical functions. ie, no electric start, horn, lights. think i have a bum ignition? or am i right in thinking that i just need the right part? thanks again and happy safe riding to all, marc.... HAPPY FATHERS DAY TOO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Click here > for replacement ignition switch from Z1E

Good Luck!

i believe one style is considered a generator while the other is an alternator

benjamin wrote:

thanks to all who expressed their thoughts and ideas. i believe it was a simple stupid mistake. i was using the wrong manual for the job. as posted earlier, i looked up the correct torque value and it was 18 ft lbs. thanks you guys.

by the way, the latest post shows two different style rotors, one appears to be a "male" and one is a "female" style in terms of how it rotates inside or outside of the stator. thanks again, now i can move on to the nest step of the project.

thanks again and happy safe riding to all, marc.... HAPPY FATHERS DAY TOO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Benjamin/Marc, Please review the "Crankshaft Tapers" "Woodruff Key" "Style Of Dynamos" note the differences in a 1976 Crank, and a 1980 Crank. I sent you a PM last night, and I'm not sure if you understand how the Member to Member Message System works. There are no stupid mistakes when you're learning.

Early Cutaway Showing "Key Way"



Early Dynamo (Alternator)



Later Dynamo (Alternator) Break-Down "No Woodruff Key".



Which Crank are you using? And what Parts are you using on Which Crank?