getting ready to do top end on my 2002 kdx 200. I hear that there is supposed to be an i. d. letter stamped somewhere on cylinder (a,b,c,or d) cant find it for ordering new piston. where is it located. Also while im here please tell me if I look into exhaust port with pipe removed arent I supposed to see the kips valves or something. All I see is the piston and no valves (maybe its in open position from carbon or is it supposed to look like this) Noticed a slow responce from rolling on power lately. Done all my jetting-45 pilot, air screw1/2 turn out (any more out and will produce a bad bog off idle) needle in 2nd from top and a 152 main was running good until lately thanks