Oh dear - it sounds like they messed up your igintion timing. FYI, its well worth continuing with the mod. I have removed my rotor completely from my 650L racer (ie total loss ignition, the pickups on the 650L being on the RHS of the crank) and the engine spins up so quick Ive had to beef up the clutch. Stick with it, tho you are likely to have a problem with easier wheelies and/or clutch slip using std springs but Id get the rotor as light as you can if you want fast response. HTH!