...on another note, it seems I may have a big bore Curtis Sparks MX pipe....the O.D. of the end of the head pipe, where the stinger fits over, on mine is 1.130". It seems the standard bore Sparks pipes are 1.115", from what I have read. Maybe I need a new head pipe altogether, since mine is not a BB, and only 269cc. Dang, this is a mess.....