1981-1984 Official Honda ATC250R Shop Manual, Page 50Get this manual
r:::iiJ HONDA CYLINDER HEADCYLINDERPISTON
CYLINDER HEAD
ATC 250R
Remove the spark plugRemove the six flange nuts attaching the cylinder head to the cylinderNOTE To avoid warping the cylinder head, use crisscross pattern to loosen each nut about 14 turn, then remove the nuts
INSPECTION
Check the cylinder head for warpage with straight edge and feeler gauge in the directions shownSERVICE LIMIT: 0.20 mm (0.008 in)