Buell  S1, S2, S3, M2, X1 models rear pulley 61 teeth, ( replacement ) 

specification 61 Teeth. Can be mounted on Europe Tube frame models to enhange the accelerating

Fit's on S1, S2, S3, M2, X1 all models. all years.

replaces Oem partnumbers G0400.8A & 34927-94Y