This paper describes the results of 63 full scale motorcycle/car impact tests to evaluate the effects of various add-0n engine guard treatments on impact performance. Test variables included engine guard presence, engine guard design, motorcycle type, and impact configuration. Dynamic measurements comprised photo-optic time histories and measurements as well as electronically sensed dummy accelerations. For each test, a set of kinematic injury potential indices were calculated from the dynamic measurements. Differences in kinematic injury potential, due to the addition of various engine guard treatments and variations in other test variables, are discussed. Conclusions and recommendations are presented.