Keyed rotor on keyless crank?

Hey folks!

I've got a problem. I spun a rotor. Its galled good inside. The crank is actually ok though. Seems like the crank was much harder than the rotor. I believe with a little bit of lapping that the crank taper will be fine.

I have a spare engine with a keyed rotor. Can I used this rotor? will it work? its a '77 kz1000 engine. My rider is a '78 kz1000. I'd swap the whole crank, but the runner '78 has a falicon super crank so I really want to make it work.

Thoughts? Do i need to keep searching for a keyless rotor?

No you can't the taper is different.

If both rotors are the same early type that run inside the alt windings then YES you can use the keyed rotor and the tapers ARE the same on those.
The later MK2 engine with larger taper also runs a different style dished rotor too so there's no way you could mix up the two.
The larger taper is actually the same angle as the earlier crank but it is on a larger diameter.

zed1015 wrote: If both rotors are the same early type that run inside the alt windings then YES you can use the keyed rotor and the tapers ARE the same on those.
The later MK2 engine with larger taper also runs a different style dished rotor too so there's no way you could mix up the two.
The larger taper is actually the same angle as the earlier crank but it is on a larger diameter.

Agree, I've been running an earlier Z keyed rotor on my Z1R for a while now, the original was starting to come apart from the steel boss. keep away from the 1000J model onwards, not only are the rotors different but so is the starter system

I thought so. The late rotor won't work on a Z1/KZ 900 because of the larger bolt required?
Steve

swest wrote: I thought so. The late rotor won't work on a Z1/KZ 900 because of the larger bolt required?
Steve

Yes! bigger 10mm bolt compensates for lack of woodruff key on the later rotors.
Keyed crank with 8mm bolts needs the keyed rotor otherwise it will spin and chew the taper.

Awesome, so I'm ok to run early keyed rotor on later keyless crank provided I use correct torque for the larger 10mm bolt.

Just wanted to clarify to ensure we are all on the same page!

Alright, follow up. I used the keyed rotor on my keyless crank. I applied loctite 680 retaining compound to the taper before assembly. I used red loctite on the rotor bolt and sent it on home with my Milwaukee m12 impact. I'm guessing I got around 50-60 ft lbs.

I let it all settle and set up for 24 hours and I'm happy to report that the taper is holding nicely. I would recommend the 680 retaining compound to anyone with a spun taper. It can fill 15 thousandths gaps and is meant for exactly this application. Alternatively, if you've got worse gaps, 660 will provide a little less strength, but is designed for 20 thousandths gaps. Both are from the retaining compound line and are meant to fix sloppy press fits and failed keyways.

I worked on a Aprilla 650 and it called for Lock Tight blue. OK, so I used some on my Z1 rotor. It was coming apart like they do, I had to heat up the rotor with a torch to get the DAMN thing off. If the fit is good, I'll stick to just tightening it up.
Steve

I agree that a good fit is probably sufficient; however, I'd already spun the crank. I am 110% certain that I'll need to use a torch when the time comes to remove this rotor. I would ONLY suggest this to someone who has an already damaged taper.

With that said, I never intend to remove this rotor. Ever.

Never say never. These rotors are notorious for coming apart. Instead of one pin keeping the clutch from shifting, it has holes for three just not in the clutch. That's the problem. Back in I guess 77, I had one get sloppy, kept riding it until rrrrump. It froze up. :ohmy: I had a hell of a time getting that cover off. I used my flat bar and wood chisels to eep it off, one side and the other. Finally I got it off. I took out the rotor and had kick start only and had to charge the battery every day when I got home from work. $350 later I had a new one. That was a lot of money for me back then. My rent was $155 including utilities!
Steve