This paper describes the results of 101 full scale motorcycle/car impact tests to evaluate the effects of various engine guard treatments and impact configurations, and also the effects of a passenger and vehicle speed combinations on impact performance and kinematic injury potential (KIP) for various motorcycle models. Included were seven different impact configurations, two moving/moving speed combinations, tests with and without passengers, three different add-on engine guards and three different motorcycle types. The impact dummies used were a partially instrumented fiftieth percentile male Hybrid II (operator dummy) and fifth percentile female (passenger dummy). Data included dummy and vehicle trajectory information from high speed films and electronically measured accelerations. Changes in kinematic injury potential due to the addition of add-on engine guards, passengers, and speed variations were analyzed. Conclusions and recommendations based on statistical analysis of the data are presented.