1999-2004 Honda TRX400EX FourTrax Service Manual, Page 119Get this manual
CYLINDERPISTON Apply oil to the cylinder wall, piston and piston ring outer surfacesRoute the cam chain through the cylinder and install the cylinder over the piston while compressing the piston rings with your fingers,
CAUTION:
Be careful not to damage the piston rings and cylinder wall
Apply oil the 10 mm cylinder bolt threads and seating surfaces and install them with the washersTighten the bolts in crisscross pattern in or steps