1986-1989 Honda TRX250 FourTrax 250R Service Manual, Page 60Get this manual
5CYLINDER HEADCYLINDERPISTON SERVICE INFORMATION TROUBLESHOOTING
CYLINDER HEAD CYLINDERPISTON
SERVICE INFORMATION
GENERAL
All cylinder head, cylinder and piston maintenance and ins pection can be done with the engine installed Before disassembling the engine, clean the outside of the frame and engine thoroughly to keep dirt and dust out of the cylinder and crankcase Remove all traces of gasket material from the mating surfaces of the cylinder headcylinder and crankcase Clean all parts before inspecting Before assembling, apply clean 2-stroke engine oil to all sliding surfaces Under racing conditionsthe piston and rings should be replaced after 30 hours of runningThe piston pin and small end connecting rod bearing should be replaced after 30 hours of running Optional oversize pistons and piston rings are availableRefer to page 1- 15
SPECIFICATIONS
Unit: mm (in) ITEM Cylinder head warpage Cylinder 1.0A
STANDARD 0.05 (0.002) 66.030-66 .040 (2 .59961 -2 .60000) 66.020-66.029 (2.599212.59957)