On the front end of my rebuild on 71 cb500. Started with the engine first then on to the fancy stuff. Bike was running when I bought her but had a small leak on the #2 cylinder. Skip ahead and I get the jugs off to discover a 1in hole in the #2 piston. Found the chunks of aluminum in the oil pan, miracle they didn't get stuck in the gears. Good ol honda has 20k miles and was still running on three pistons.
My question what would cause the hole? My first thought was the valves getting hit but they are fine and seated. An old mechanic said a vacuum effect caused to much oxygen to get in and it exploded causing the weakest point (piston) to give. Any thoughts?
My question what would cause the hole? My first thought was the valves getting hit but they are fine and seated. An old mechanic said a vacuum effect caused to much oxygen to get in and it exploded causing the weakest point (piston) to give. Any thoughts?