Has anyone had a problem with an engine noise that is hard to diagnose. It sounds like piston slap that gets louder as motor revs up. To date I have done the following with no success: -Changed piston rod, new piston/pin/circlips, checked measurement of the cylinder, new cam chain and adjuster,checked valve clearence, visual check of all bearings, gears and clutch assembly. I have not replace any bearings because they all felt ok when I inspected them. I am totaLLY STUMPED.