On rolling starts and down the straight a ways, how does your kart compare? Are the other engines EVO? What rpm does your clutch stall at?
FYI- The new style clutches came out a few years ago. Along with the new clutch and drum came metal gears to replace the nylon ones. IMO you should have upgraded the clutch along with the EVO mods.
LAD Specialties customer / tony kart / rotax / kt100