Crank, rocker arm and piston
could you scale what you found to the right size? or just make your own to match?
Sometimes the best things are made when you build them yourself, however quick fix, just scale what you have. Have you tried other sites for cad files, grabcad is hands down the best for what I do. But I think Solidworks has there own file sharing community and so does 3dvia. Honestly though other sites may be quite a long shot. I ran into a similar issue a few months ago, scaling is what I should have don from the start.