In this study, by performing a dynamic modeling of a four-stroke single cylinder engine, its dynamic behavior in acceleration period under loaded and unloaded conditions, vibrations of engine block and angular velocity fluctuations of the crankshaft were investigated. The dynamic model consisted of motion equations of piston, connecting rod, crankshaft and engine block. The motions of the engine block and the other moving elements were described on a plane perpendicular to the crank shaft axis. The block of the engine has two degree of freedom; one is translational motion on the direction of the cylinder axis and the other is angular vibration around the crank axis. Numerical solution was performed on time domain by means of using initial conditions. The working gas pressure exerting on the piston was obtained experimentally from a four-stroke single cylinder diesel engine. The vibration characteristics of the engine components and forces occuring on the mounts were graphically presented.