Posted by Jack Smith on February 18, 1999 at 00:10:45:
In Reply to: Hole in Piston, Expert Opinions Please !?!?! posted by Sean Butler on February 17, 1999 at 22:22:19:
Sean,
Sounds like the loose plug allowed an air leak, leaning the mixture to that cylinder. Remember that the pistons are all locked together on the same shaft, so a lean cylinder gets dragged along until it melts the pistion crown. The hesitation you felt was when it burned through. This is common on V-twin motorcycle engines. The term "hot plug" usually refers to the electrode temp of the plug itself, relative to running without fouling. A hot plug doesn't really cause the cylinder to run hotter, but it couldc ause ignition to falter in that cylinder. Too cold, and it'll foul, too hot and it'll erode too quickly. While there are misconceptions about plug heat ranges, I doubt if a hot plug could cause your piston to burn. I'd vote for a leanout. Before you put it all back together, be sure to check and double check all the intake manifold nuts & bolts, and look closely for cracks. There may be other leaks. One more thought would be when you assembled the engine, did you get all the oil squirt holes for the pistons lined up right? (correct rods in correct holes) Good luck, and have fun!
Regards,
Jack