My riding friend Angel, who has a Carbon Fiber ZZR 1100 C model had a very lucky escape. He recently did a little work on his bike and when he was putting the airbox back he noticed he was 1 screw short. He had a little look but could not find it. Oh well he thought, not a problem.
Well, he was having trouble starting the bike and he push started it. When the engine started the was a sound reminiscent of a valve issue. A loud tapping noise. He initially thought it may have been the cam chain tensioner. He checked that and all seemed OK. Concerned that it it was indeed a valve issue he RODE IT to a mechanics. There they started to strip it to find the issue. This is what they found!
The airbox screw had fell into the carb and then into the head. There it had come into contact with a valve but, in a chance in a million, it had caused the shim to come out of position
A closer image of the displaced shim.
There are so many things that could have happened and none of them good. What is even more amazing was once the screw was removed and the shim put back in place the bike ran fine!