I was cleaning the carbon off my piston and while scraping, noticed that the piston can rotate ±5 degrees in the cylinder. Shouldn't it be completely constrained, except for up and down?
Is my wrist pin wearing out? Thanks for any help
oh man, no no no. if it is twisting, you need a new gudgeon pin and bearing. its ok if it has a slightly side to side perpendicular to the rod, but twisting is a sign tht wrist pin ( gudgeon) bearing is bad or not the right one. i use a wrist pin bearing made for stihl chain saws. it's slightly wider and thicker than the stock bearing. i get it from a small engine and power tool shop a few miles from my house. they cost me like 5 bucks each. well worth the money when you compare to a new jug, pin, piston and rings.