In this study, a thorough in-cylinder flow analysis is performed to visualize the actual flow traits through the intake & compression strokes of the crank-rocker engine. For this purpose, particle image velocimetry (PIV), which is a method for flow visualization is used to better understand the air-fuel mixing and flow properties. CFD was also performed with Re Normalized Group k-ε model to validate the results using the widely used commercial software CONVERGE. The results of PIV experiments were in agreement with the CFD results to the highest degree. The tumble and TKE were analyzed at cold-flow conditions and the initial and boundary conditions were used in CFD analysis to validate the results. This study helps in understanding the flow characteristics of crank-rocker engine numerically and experimentally. © 2023 Elsevier Ltd. All rights reserved.