mystery piece in a long owned belt drive setup

Hello to all,

After a long pause I'm back on the basket case known as XBSKT2

On to the primary while the front end waits.

Long ago I bought a belt drive setup from a vendor named Art Xanders. It was cutting edge over ten years ago and went on a shelf till it was time to build the "next" basket case.
Art has long since left us here on Earth from what I understand. There were no instructions and I believe the installation should be fairly straight forward. One curiosity is a mystery disc that is in the kit. I think it is supposed to be used to help the front pulley be pressed on by the rotor nut so as not to damage the aluminum front pulley. That is all I could come up with. The disc seems to fit well on the crankshaft and it seems the right size and thickness to relieve the stress of installation from the hub of the pulley.
Any one care to opine?
Please see a few pics of the kit on my too-long-dormant photo bucket album.
Look for the pics at the bottom having to do with the primary.

http://s957.photobucket.com/albums/ae58/xbskt/

Any help appreciated.

Jeff

That could be the use of it. Another is if it is larger in OD than the front sprocket--it is used as the outside belt retention disc to keep the belt from running off the sprocket in case of misalignment. Some kits have something like this disc included.
Wait to see what other feedback contains---could be entirely different use.

It looks like my fair spares kit, it is to retain the belt on the front pulley.

You can kind of make it out in this picture.

It looks like my fair spares kit, it is to retain the belt on the front pulley.

Click to expand...

Same as mine and there should be an inner one screwed to the pulley. For the outer I filed a slot in the bore to clear the rotor key. (Made it easier to assemble the key without the end plate in position on mine).