Correct seating of sprocket on crankshaft

My chain parted and chewed a piece out of the inner primary case earlier this year. I had that repaired and now I'm putting it all back together again.

Here's where I'm at ...



And a close up of the sprocket / crankshaft ...



The manual calls for the sprocket to be drifted onto the crankshaft to seat the sprocket onto the woodruf key, which I did.

My question is, how do I know I've tapped that sucker in enough? Visibly it all looks good but is there a measurement that I can make to make sure it's seated correctly?

Any help, advice, comments most gratefully received.

Over to you Norton Guru's!

Nellie_Rocks said:

The manual calls for the sprocket to be drifted onto the crankshaft to seat the sprocket onto the woodruf key, which I did.

Click to expand...

What the factory manual says is: "......push the sprocket fully home over the woodruff key, if necessary using a tubular drift to push the sprocket fully home." (my underline)

If you re-fit the parts you removed (shims, rotor spacer and rotor) the sprocket will be pressed onto the crank taper when the rotor nut is tightened to 70 ft. lbs..

Thanks - I was thinking that tightening up the nut would finish everything off but always good to hear it from a place of experience.

BTW - I see you're in Norfolk (UK), my home town is (was) Wolverhampton but know displaced to Napa, California. Bummer ...

Nellie_Rocks said:

my home town is (was) Wolverhampton but know displaced to Napa, California. Bummer ...

Click to expand...

A true Wolverhampton wanderer! :wink:

I would suggest, if you haven't done already, remove the crank and clutch sprockets and primary chain again. Then replace the sprockets without the chain and lay a steel ruler across both of the sprockets teeth. This will show if you have perfect alignment for the primary chain.
Add or subtract shims behind the clutch if needed.

What do you think caused the primary chain failure?

Have you shimmed the clutch hub to square the hub to the sprocket?

The sprocket is of course fixed by the taper and adjustments are made at the clutch hub with shims on top of the clutch locating washer.

This is done with the chain laying aside and a straight across the facing teeth of both units.

Thanks Guys - I was thinking the same and I'm kicking myself I didn't do it before, I was relying on the original spacers to re-align the sprocket and clutch again. I think I will pull them off and check alignment before re-installing the primary chain.

The primary chain wasn't my original issue, the final chain parted and chewed out the splash guard on the outside of the inner primary case - just glad it didn't happen at any meaningful speed ....

I guess we all assumed you were talking about the primary chain parting.
i was going to say that whomever repaired the primary case was a real artist as I couldn't see any repair scars.
Knowing it was the drive chain cleared that up.
It is always a good thing to check the primary chain alignment since you have it torn down anyway.