There's a nice, local lad who just moved to Toronto to go to school. He's a regular at one of our weekly meets. His ZZR250 began making odd sounds and running really rough. He pulled the motor and ripped it apart and did not find anything wrong. The same symptoms exist (see/hear video in the first link). The other links are more about the problem and the tear-down. Any ideas?
CCT thread makes me think that one of connecting ends is bent... I'd say bearings, but then it should always be loose (assuming the plugs are out when he is doing these tests)
Pretty sure a factory service manual will list tolerances for things like run-out and what have you. Yes, it will be a time consuming task to spec out the engine...but if he's going to tear into it again why not make sure everything is as it should be? He's obviously mechanically inclined enough to not only tear apart an engine, but also put it back together. Point him down (what I think to be) the right road, and make him check the measurements of the 'knowns', maybe map out the 'unknowns' as well.
And I must disclaim. I am not a professional mechanic, and very very rarely go past the head of an engine. I do not have the patience nor skill to build an engine.
if you love your motorcycle, set it free.. if it comes back and hits you.. you highsided