Toro 500 EFI Service Manual page 86


NOTE: Note the direction of the exhaust side of the
piston (5) for correct ring end gap orientation.
2. The ring with the orientation mark (MTOP or TOP)
should be installed in the second (middle) groove
and the ring with the orientation mark (M or O)
should be installed in the first (top) groove.
CAUTION
Incorrect installation of the piston rings will result in
engine damage.
CYLINDER /CYLINDER HEAD
ASSEMBLY

NOTE: If the cylinder/cylinder head cannot be trued,
they must be replaced as an assembly.
84
Cleaning/Inspecting Cylinder Head
The cylinder head studs must be removed for this pro-
cedure.
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 com-
bustion chamber or the sealing surface.
2. Inspect the spark plug hole for any damaged threads.
Repair damaged threads using a "heli-coil" insert.
3. Place the cylinder head on a surface plate covered
ATV-1085B
with #400 grit wet-or-dry sandpaper. Using light
pressure, move the cylinder head in a figure eight
motion. Inspect the sealing surface for any indication
of high spots. A high spot can be noted by a bright
metallic finish. Correct any high spots before assem-
bly by continuing to move the cylinder head in a fig-
ure eight motion until a uniform bright metallic
finish is attained.
Water or parts-cleaning solvent must be used in con-
junction with the wet-or-dry sandpaper or damage to
the sealing surface may result.
ATV-1024A
Measuring Cylinder Head Distortion
1. Remove any carbon buildup in the combustion
chamber.
2. Lay a straightedge across the cylinder head; then
using a feeler gauge, check the distortion factor
between the head and the straightedge.
ATV-1024B
3. Maximum distortion must not exceed specifications.
CAUTION
CAUTION
CC128D