Topic: Reinstalling rotor- Question

[scondon]

   I finally got my bored cylinders back and am able to finish putting this engine together. I'm putting the rotor and starter clutch gear back on the crankshaft and something doesn't seem right. Since the rotor is generally pretty hard to remove from the tapered end of the crank I figured I might need to whack it with a rubber mallet to get it to seat back on the taper. But it is all the way on and still spinning freely. I tightened the rotor bolt just a bit(about 12 ft/lbs) and then backed it off and the rotor still spins free.

   My question is this, will the 80 ft/lbs of torque on the rotor bolt be enough to press the rotor on the shaft? Is it normal for the rotor to spin free until fully torqued down?   

[mrbreeze]

Sean,I haven't been there before(yet!!) but without even going to the book to research what you're describing....does this not have a key to hold it in place? Most things that bolt to a shaft have a keyway in the shaft with a key to hold it in position.Then you torque a nut to hold it all together.Like a harmonic balancer or something. If I'm full of sh!t,I'm sure someone will be kind enough to point it out to me!!!!

[scondon]

 Thanks for the input,Fred   The rotor is just a press-on fit to the crankshaft with no keyways or locating pins. The inside of the rotor is tapered to press fit to the tapered end of the crankshaft.

  I may be OK with this rotor. I was just expecting SOME resistance as the rotor was placed on the shaft

[Patrick]

The bolt pushes the rotor down on the taper, but I could have sworn there was a woodruff key that fit into a slot on the crank. All my other bikes have that key. It's been a while since I pulled the rotor, though, so my aging memory might be faulty....

Patrick

[scondon]

Not sure what bike were talking about but on my 550 the torque from the bolt alone fully seated it on the crankshaft, I dont recall any free spinning but then I dont remember attempting to spin it until the bolt was fully torqued. Good luck with the rest.

   Doh! I keep forgetting that vital info. It's a '78 CB750.

   The rotor stops spinning on the shaft as soon as I apply torque to the bolt. I just figured that if I backed the bolt off after applying a little torque there would be some indication that it was beginning to "press-fit" but it's still slipping off the shaft(spinning free).

    I can't apply 80 ft/lbs of torque to that bolt until the engine is in the bike. Just wanted to know if something is amiss while the motor's still on the stand.