kdx200 noise Hmm ???

Hello,
I have just bought a 2002 model kdx200. 2700klm on the clock.
the bike looks as close to new condition as you would ever find so I would say the 2700klm is right , Not even paint wear on the frame.
I have never heard one of these start up before, But mine has a knocking sound from the Top end that sounds like piston slap.
?? I have only ridden it up & down the street , Seems to run fine, stops & steers like new. Smokes bad on Idile, some oil from the flange,
& it has a knocking sound from the Top End. As I say it looks new.
Do they all knock ??? any Ideas ??

Thanks Peter

thanks for the Reply, It certainly has me worried , Can;t hear in while Riding just on Idle. I need to get on the dirt & give it a good go I think . Up & down the street a couple of times is not much of a test. When I heard the knocking I thought perhaps I should take the Head off & have peek at it .
But if think they all sound like that, I might take it for a good ride & see what happens. Mine is blowing lots of smoke on Idle & I think the pipe must need a go blow out . The Guy who own it just Rode it to work sometimes so I'm thinking the smoke must be from a oily pipe.
I cleaned out the tank & refueled it at 32:1 .

Ok Guys , I took it for a good run & it became louder. I pulled the Head & barrel off & now I'm looking for some identification marks on the Piston.
It has an A stamped on top ! Inside the piston is a little Star emblem with a 3 in it & maybe a K or an A?? Above that is stamped 1.
There are no scores in the Bore, It looks like it would clean up ok. The conrod has a lot of play in the bottom end , No Carbon build up in the Head.
The ports are all clean. Any Ideas what Piston I have ?
Thanks peter

Just some feed back on this bike, The piston & the bore are in good shape with low miles. I took the piston & bore to a Motorcycle mechanic.
He said it's all fine , Some small blow by , but it's in good shape.
As I had already ordered in a new piston kit for it , I will put it in anyway. I'm pretty sure I found the problem . The main Kips connecting shaft had a stripped nut on the left hand-side of the motor.
It appears it was put on crooked & it is not possible to know how tight it was done up because it was stripped. I guess that would certainly explain the noise. I tied to buy a new shaft but, there there is none in the country & it would have had to come from Japan "6 weeks "
I got a new nut & the shaft looks straight. The tread is a little bent over where it has been forced when they stripped it, So I will put a bit of lock-tight on the nut. The rest of the kips parts were all in top condition , only a little dirty. I will put it all back together with the new piston kit even though it's not need & see how it
sounds. The bike is in great condtion with only2700kml on the speedo, I have been looking for a KDX in this condtion for along time

. IMG]http://i579.photobucket.com/albums/ss235/howesvalley/DSC07749.jpg[/IMG] peter