1986-1989 Honda TRX250 FourTrax 250R Service Manual, Page 66Get this manual
CYLINDER HEADCYLINDERPISTON Install the bearing and piston pin in the connecting rod smal end and check for excessive playIf it feels loose, measure the small end 10 SERVICE LIMIT: 22.022 mm 10.8670 in) If not over the service limit, replace the piston pin and small end bearingIf over the service limit, replace the crankshaft assembly
Insert the piston rings into the cylinderUse the piston to place the ring squarely in the cylinderMeasure each piston ring's end gap with feeler gaugeSERVICE LIMIT: 0.5 mm 10.02 in)
CYLINDER AND PISTON SELECTION
The cylinder and piston are select fitted Select new proper piston and or cylinder as follows: Piston selection Record the 0.0code on the piston head (1)