For you engine builders and spurts, why did the factory put different size shims on that engine? Were there some 1/1000ths out of spec in some places? Could the factory even measure such a small amount trying to decide this size shim and that size? I thought I heard him say the shims on one side were one size and on the other side another size.
Shims are for fine tuning valve stem/bucket style cover, to cam lobe clearance.
They usually all vary a few thousandths from new. As you Cannot machine perfect tolerances into multiple parts, especially all requiring such small clearances.
If the shim size was too small(loose) from the factory...the engine would have ticked/rattled noticeably from it's first start, and continuously from there on until the shim was replaced with the correct size.
No way it left the factory, and the dealer that way, and the customer not hear it either.
Not the problem.
As for hitting the rev limiter;
In gear, with the engine loaded, there should be no issues, as the rev limiter is pretty conservative...and it's there to Prevent over rev damage.
Correct me if I am wrong, but you cannot redline the gen3 in neutral(ecu safety), but you can pull the clutch and redline it in gear, as if the engine were in neutral.
If you do that, and bounce off the rev limiter, that puts alot more stress on the engine, as there's no load on the engine.
It's like missing with a punch.
As for the air/fuel being too lean? No.
Lean? Yes
Dangerous? No
Performing well? No
Plenty of full exhaust untuned engines still running fine.
The Proof? Look at the engine internals.
Nothing is visibly damaged from a lean condition.
Only one cylinder had a problem.
The keepers on #1 cylinder, and/or the valve stem where they fit, failed.
One of those parts(possibly even the guide) was either an out of spec part, had a stress fracture, or some sort of defect in the manufacturing process.
That part(s) failed under circumstances it should have been able to withstand for 100k+ miles(with valves adjusted when needed).
The Dealer doesn't like that guy for whatever reason, otherwise they would've warrantied it for him.
Fortunately, the guy knows how to fix it(doesn't have to be concerned if someone fixed it correctly or not).
He can afford to(which is great, but aside from the point).
And, he's back up and running already(his bike would probably be at the dealer a long time).
