http://www.wiseco.com/ProductSearch.aspxmeasure your cylinder and look good in this list, which piston you need . your old size is 85,94, than is your needed size 85,95 in cast!
if you replace a cast-piston by a forged piston you have to know, that forged pistons need more clearance, caused of the different material character. a long time ago i found out that cast pistons with the same mark on the top, are a little bit bigger than forged pistons.
forged cast
- = A
A = B
B = C
C = D ...
feel free to contact wiseco for the right piston size and your problem with the rattling in the motor will be gone forever. than it will sound like a swiss rolex...
you heared motorads bike in the video,
the C -size cast piston, you found in your motor you can get at all kawasaki-dealers . the stock pistons and con rods, that kawasaki build in all kx-modells are made by prox in japan, but without the prox-logo in the inside.