ATV-1069 ATV-1085B 2. Install the compression rings (1 and 2) so the let- Measuring Piston Skirt/ ter(s) on the top surface of each ring faces the Cylinder Clearance dome of the piston. Rotate the rings until the ring end gaps are on directly opposite sides of the pis- 1. Measure the cylinder front to back in six places. ton according to the illustration. NOTE: The chrome (silver) ring should be installed in the top position. 3 CC397D 2. Measure the corresponding piston diameter at a point 15 mm (0.6 in.) above the piston skirt at a right angle to the piston-pin bore. Subtract this MD1343A measurement from the measurement in step 1. The ! CAUTION difference (clearance) must be within specifica- tions. Incorrect installation of the piston rings will result in engine damage. Installing Piston Rings CYLINDER/CYLINDER HEAD 1. Install ring expander (4) in the bottom groove of ASSEMBLY the piston; then install the thin oil rings (3) over the expander making sure the expander ends do NOTE: If the cylinder/cylinder head assembly not overlap. Stagger the end gaps of the upper and lower thin oil rings according to the illustration. cannot be trued, they must be replaced. NOTE: Note the direction of the exhaust side of Cleaning/Inspecting Cylinder Head the piston (5) for correct ring end gap orientation. ! CAUTION The cylinder head studs must be removed for this procedure. 1. Using a non-metallic carbon removal tool, remove any carbon buildup from the combustion chamber being careful not to nick, scrape, or damage the combustion chamber or the sealing surface. 2. Inspect the spark plug hole for any damaged threads. Repair damaged threads using a "heli-coil" insert. 3-17