If my XT was allowed in the pre '75 class which, as I read the 2011 MOMs, says "cut off at '76" Rule 18.10.0.1. I would be fine with a split at pre '75.
Pancho...I don't know where you got the 1976 cutoff for
pre 75 my 2008 rulebook states
in Rule 18.10.0.1...
For the pre 75 class, all performance parts must be manufactured before December 31 1974. There is no way an XT/TT500 Yamaha will ever be eligible for the pre 75 class due to their 1975 release date.
The 2 valve stipulation stems back to the original 2 valve class which was never intended to be a vintage class. It was designed to entice the then dormant Jawa and JAP sliders out of sheds and onto tracks. Back in the 90s I proposed that "production based" OHC engines be allowed to compete in the 2 valve class but the powers that be on the commission at that time didn't share my vision so it was knocked back. Interestingly, the big Condo meting every year had it's own sup regs and they allowed XT powered sliders. Chris Ellis proved how good a Yamaha slider can be when he battled shoulder to shoulder with the great Gary O'Brien on his JAP at the final Condo meet. Chris's efforts inspired a number of people to build XT sliders but the authorities stuck by their guns outlawing them.
You've raised a valid point that the rulebook needing a good going over, sooner than later. The wheel size stipulation is especially ridiculous and I don't recall it ever being used to refuse a machine. As it stands now Wally, your XT500 slider fits comfortably into the pre '78 class.