Change the chain case seal band or leave it?

I took my chain case off to change the oil (thanks to everyone for the advice!). The oil was indeed really dirty and appeared to be the wrong type. I cleaned it up and am about to reassemble it.

Planning for this work, I picked up a sealing band (gasket) for the chain case. The bike hasn't been touched in 6 years and I imagine the gasket is 10+ years old.

I'm not an expert at inspecting this stuff, so pardon the simple question. The gasket doesn't feel brittle, and has a tacky, rubbery feel with friction. In other words, it's not clearly damaged. But since I have a part, and it's open should I just change it? Or if it's good enough would you just leave it?

Also, if I fit a new one do you suggest putting grease on the new seal? A little clean oil? Nothing? Thanks!

Anything else look like it needs attention in the case?

If not damaged or stretched I would re-use and fit it dry, but get ready for more than 1 right answer

If it ain't broke, don't fix it.

If you got a new one replace it and keep the old one as a spare, but if I didn't have a new one I would use the old one.

It must sit proud of the inner cover slot so you get a seal, replace if its flat.

I use a smear of clear RTV on the cover.

kommando said:

It must sit proud of the inner cover slot so you get a seal, replace if its flat.

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It was flat. Thanks, this was a good detail!

Thanks everyone! This would be an obvious "might as well change it" with assembly line bikes but when each Norton fits together a little differently I'm hesitant to just replace parts. The seal is low risk, but anyway.

I replaced it. The old one was still a bit tacky, but flat on the seal side. I figured when's the next time I'll be in there (wishful thinking), and I have the part sitting here..

I've been buying the $1 rubber bits and washers freely whenever I do a big Andover order since I'd rather have them on hand for a job instead of paying shipping when I need it.

Now I'm checking out this Sparx component in there wondering if that needs attention. I've read some negative comments on them here in the forums.

Nortorious said:

Now I'm checking out this Sparx component in there wondering if that needs attention. I've read some negative comments on them here in the forums.

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Their rotor/stator are great. A bit more output than Lucas. I've had one for almost 15 years and the only problem was that the regulator fried due to a short circuit. Replaced that with a big Shindegen MOSFET shunt regulator. I get 14.5 volts at 2000 RPM. The regulator worked well until I shorted it out and destroyed it.

The weak spot of this design is where the wires exit the stator. Be sure to keep a "service loop" there and avoid bending the wires at 90°. This applies to any brand of that design.

One of the biggest reasons to go to belt drive is that that damned primary always seems to manage to leak. Good luck!