the rod cant slip on the crank without breaking, and the rod is built for the engine so it will fit, first starts are hard, here is what will make it easier, take the glow plug out, drop 3 drops of after run oil in it, put it back in, take the air filter off, drop 3 drops of after run oil in it, then, when you go to start it (after isntalling a new pull start) heat it up with a hairdryer for 2 or so minutes until its hot, since these engines dont have piston rings like cars, they rely on something called pinch for compression, the top of the cyilinder is smaller than the bottom, but when ti heats up, it expands, make sure you do a proper break in too