zxr250 engine timing...?

Is there such a thing... wait.. there probably is... what do we call it and how is it adjusted? (Not technically, I meant how do we know then it's at the right spot.)
The reason I'm asking is that before leaving work I was having a chat with an old friend (who I hooked on to netrider btw, as she was interested in getting her bike L's) at my bike when I started it.
We were having a bit of a chat, and just before I got my gear on to leave she mentioned "ooh, you might want your bike looked at, listen to the engine purring.." It was not in rhythm, and there was a couple of breaks in the rumbling.
She used to race cars, and she mentioned that its just akin to tweaking the carburetor or checking the timing belt (which I have no clue about.)
And once done it'll run a lot more smoother.
Does anyone have any tips on how to do this right for a total noob? Or is it just better to take it a mechanics?
Or..... "bikes are cars are different okay?"
Anybody?
The reason I'm asking is that before leaving work I was having a chat with an old friend (who I hooked on to netrider btw, as she was interested in getting her bike L's) at my bike when I started it.
We were having a bit of a chat, and just before I got my gear on to leave she mentioned "ooh, you might want your bike looked at, listen to the engine purring.." It was not in rhythm, and there was a couple of breaks in the rumbling.
She used to race cars, and she mentioned that its just akin to tweaking the carburetor or checking the timing belt (which I have no clue about.)
And once done it'll run a lot more smoother.
Does anyone have any tips on how to do this right for a total noob? Or is it just better to take it a mechanics?
Or..... "bikes are cars are different okay?"

Anybody?