I've been racing a '75 Z1 for 5 years (over 60 races and the motor's still strong).Stock except for a Wiseco 1015 kit,Progressive shocks and fork springs,and Avon race rubber.A bit of a handfull,but great fun to ride.I bought a Rickman frame and 2 motors a few years ago,but couldn't afford a build.This year the company I work for sponsored the motor work-a '77 motor with a 1075 Wiseco kit,welded crank,headwork,29mm Mikunis,and race rubber.I hope to have it finished in a few weeks,and race it with the VRRA and save the '75 for the 2 hour endurance races.