Also, when removing the cylinder, locate the oil jet which lubricates the bottom of the piston. The jet is located inside the red circle in the photograph below. Verify this jet is unobstructed.
Also make sure the oil passage in the crankcase which feeds the cylinder head is unobstructed. This oil passage is located inside the orange circles shown in both photographs.
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Spud
"Never argue with an idiot. He will drag you down to his level, and beat you with experience."
Mark Twain
2015 Zongshen ZS250GY-3 (RX3)
2006 Zongshen ZS200GY-2 (Sierra 200)
2005 Honda XR650L
2004 Honda CRF250X
1998 Kawasaki KDX220
Mods made to my Zongshen ZS200GY-2:
http://www.chinariders.net/showthread.php?t=6894