I've got a SuperTrapp on an old 1986 XR 250 and
am looking to add some discs. I haven't taken
it appart yet, but the actual outside diameter of the discs
themselves is just under 3.75 inches. The diameter of the end of the
pipe itself is 4 inches, so I wasn't sure if these are
called 4 inch discs, or if my SuperTrapp is so old that
3.75 inch discs are not made anymore. I've seen 4 inch
and 3.5 inch sized discs on ebay...
Any info appreciated.