OK! Terry and big_jim -
I've been using aluminum plate for my mockups, to get the right center-to-center distance, using available sprockets and belts [Gates]. I'm hampered by the fact that there is not much room beneath the carbs/behind the cylinders/in front of the clutch housing. So, using the Fairbanks-Morse mag housing (pretty much universal) and the crank centerline, I've come up with 145mm c-to-c for my CB500/550 conversion. That's approximately 5 11/16". I'll be using 32 tooth sprockets, which are ~2 1/8" dia. The belt length works out to 425mm [85 tooth], for a 5T belt [5mm pitch x 16mm width].
No problem. I have it mocked up; fits fine, works OK. (On the bench - not running). But I don't really want to have the belt exposed. Too many variables out of my control unless I'm standing next to the bike all the time.
So, I really need a box to house the belt drive...
Here's what I've come up with. An aluminum conduit box. Two, actually; TIG welded together.
http://appletonelec.com/SectionProducts.asphttp://appletonelec.com/pdf/A-2-3-12-13-14-16.pdf2" Hub size; "LB" style conduit box, LB200-A or LB200T-A; "P" gives 2.75" box ID - enough to clear my sprockets.
I'll cut and weld the two boxes together to give a single rounded-end box w/2 holes on the back side, and then machine it to fit my points cover disk. And fasten it with 1/4" SHCS or BHCS. The mag will bolt on to one end, the disk to the other. I'll machine a flat aluminum cover for it, too.
I don't have the equipment to TIG weld a box that size, so I'll have to farm that work out.
(Hmmm...Who do I know that can TIG weld an aluminum box up??)