I need some help guys. I just finished a topend rebuild of an 03 YZ250 and I am getting a nasty knocking noise. It was knocking a bit before I replaced the piston and rings but now it just worries me. It mainly does it at idle and goes away around a quarter throttle (this is as much throttle as i have given it). The bike has not been started in a couple of months. Am I overlooking something small but big? Is there anyway that I could just have a jet clogged or something, or at worst do I have a bottom end issue. Any advice would be greatly appreciated. Thanks