A two-color Particle Image Velocimetry (PIV) technique has been applied to a motored single cylinder two-stroke motored research engine. In two-color PIV, two light sheets of different wavelengths are used to successively record, at a known time separation, the positions of the particulate seeds in the flowfield. By separately interrogating the two images of different color and cross-correlating them, a two-dimensional velocity field is obtained. Since the sequence of the images is known, directional ambiguity is eliminated and two-color PIV can be used to study complex, recirculating flows such as those found in an internal combustion engine.The technique is used here to measure the flow in the cup of a motored, single cylinder, cup-in-head, research engine operating with high swirl. Velocity fields were measured at several planes parallel to the piston crown. Multiple images were obtained at each plane, and ensemble averaged velocity and velocity fluctuation were determined. Laser Doppler velocimetry was also used to make point velocity measurements at a limited number of locations and these measurements were compared with those made by PIV.