i have a 2003 honda cr125r. as of today i put a brand new top end in it 5/20/10. it wasn't blown up just worn so i replaced it. it started the third kick and there was no noises. i shut it off and started it back up and now there is a noise in the top end. in only does it when its idling though. once you get into higher rpm's the noise goes away. i thought it might be piston slap but the sound wouldn't go away correct? what else could it be? crank bearings?
