Proposal of the calculation formula and the derivation method for piston inertia force of motorcycle engine that can be used regardless of the presence or absence of cylinder offset

Abstract

In recent years, the number of motorcycle engines adopting cylinder offset has increased, but there is no literature that confirms the validity of the calculation formula for the slider crank mechanism with cylinder offset, which is the basis of dynamics. We need to establish the basis of the calculation formula used when adopting the cylinder offset to increase the certainty of the crank shaft design. As a result of verifying the approximation deployment method and the order of the variables used during approximation deployment based on mass production past record for motorcycle engines, it was confirmed that the piston inertia force is expressed by the following calculation formula.