Strange noises…

I don’t know if this is all in my head, but I think I’m hearing some strange bottom end noises coming from my 03’ wr250f. I started my bike after washing it yesterday and I was hearing what I can best describe and a banging or knocking coming from what sounded like the bottom end. I would give the bike some gas to rev it up a little, and as the revs were falling I would hear the knock. This would not happen every time though. The thing is it sounded just like the knock it makes when it stalls out either from rider error or when it is really cold and not warmed up (driveline lash??). I also saw what was very light, very intermittent white smoke or vapor only when revving ( again very intermediate). However it was cool with very high humidity, so that could have been just the water vapor in the exhaust condensing. My question is should I be concerned? Is there any way to inspect the bottom end without taking the bike completely apart? My friends and are going to Hatfield and McCoy at the end of the month and I don’t want to take a sick bike.

…also, I haven’t taken anything apart yet. I’m starting that process tonight.