The way I look at it is they aren't going to take off your head, and measure the cylinder. I've had police ask me questions about my bike, and I had to educate them on the laws.
The one thing that does concern me about my kitted ped is that the head, and sprocket are black, when the stock stuff was silver. I'm wondering if that's supposed to tell the cops your stuff is not stock..
I wouldn't worry about it too much though, long as you aren't doing 45 in a 25, no one will ask questions.