'73 Yamaha MX 360 & '74 SC500.....trick swingarms.

[firko]

What's more interesting than a couple of reasonably average Yamahas is the alloy swingarms that go with them. I've been told and have read on this forum that alloy swingarms weren't generally available prior to 1975 but here's a couple....a Pro-Fab with the 360 and a AA with the 500. Add Boyd and Stellings to the mix and I think we can finally put that old phurphy to bed.
http://cgi.ebay.com/ebaymotors/Yamaha-MX360-MX360-MX360-Yamaha-AHRMA-VMX-MX-motocross-vintage-pro-fab-/280726243303?pt=US_motorcycles&hash=item415c9687e7#v4-34
http://cgi.ebay.com/ebaymotors/Yamaha-MX360-MX360-MX360-Yamaha-AHRMA-VMX-MX-motocross-vintage-pro-fab-/280726243303?pt=US_motorcycles&hash=item415c9687e7#v4-34

[mx250]

That ProFab swingarm looks like this one from Mark's swap.



http://www.vintagemx.us/cgi-bin/largephoto.cgi?C=MQRhDqbT9SmcpFfB&w=3

He wanted $300 for it (or still does ).

Interesting, but I think it would make it an LTR (and not pre75 eligible ).

Even with a trick swingarm thrown in I think $2000 is a bit rich for a seized MX360 .

[mx250]

Were you also referring to this swing arm in the other ad? This one isn't LTR so should be eligible (after a GCR fight maybe ).



A very interesting swing arm, looks cast to me.

http://cgi.ebay.com/ebaymotors/Yamaha-SC500-SC500-SC500-pro-fab-AHRMA-VMX-MX-motocross-vintage-yamaha-YZ-/280725822724?pt=US_motorcycles&hash=item415c901d04#v4-34

[firko]

The AA swingarm is indeed cast alloy. I've seen a couple of them over the years but they're not that common. This forum's Bazza was contemplating buying one for his B44 BSA but I talked him out of it because fitting it would have propelled the pre 65/70 bike into pre '75. The Pro-Fab swingarm that goes with the siezed MX360 is indeed for forward mounting but that's not the point I was trying to make. The fact that it existed prior to 1975 would indicate that a Pro-Fab alloy swingarm is legal for pre '75 as long as the suspension pick up points are in the original position. I was merely pointing offering a little proof that alloy swingarms were avalilable in 1974 to whoever it was that mentioned that they weren't available somewhere in the past on this forum. That particular swingarm isn't Kosher though, purely because of the shock mounting position being too far forward.