sure the oil passages at either end of the
cylinder block are clear (Figure 57).
2. Install the rear cam chain guide assembly
(Figure 58); use Loctite on the 2 Allen bolts.
3. Install the 2 oil control orifices and new
O-rings at either side of the crankcase (Figure
59). The end of the orifice with the small hole
4. Check the studs to the right ofthe cam chain
tunnel. If there are O-rings on the studs,
remove them and install new ones; not all
models have these O-rings.
5. Install a new cylinder base gasket on the
crankcase; the notched end of the gasket goes
toward the left side of the crankcase (Figure
6. Install a piston holding fixture under the 2
inner pistons (Figure 61).
You can easily make a simple piston
holding fixture out of wood. See Figure
7. Lightly oil the piston rings and cylinder
8. Carefully slide the cylinder block down over
the studs, threading the cam chain up through
the block (Figure 63). Tie the chain up or stick
a screwdriver through it to keep it from falling
down into the crankcase.
9. Rock the cylinder block and slide it down
over the inner 2 pistons and rings. Compress
each piston ring with your fingers as the
cylinder starts to slide over it, then slide the
block down over the outer pistons.
N O T E
the rings are hard to compress, you
can use a large hose clamp as a cheap,
but effective piston ring compressor
10. Remove the piston holding fixture and
push the cylinder block down until it seats on
the crankcase. Check that the cylinder block is
fully seated against the crankcase all around.
1 1. Install the
2 nuts at the rear of the cylinder
base (Figure 52) and the one at the front (Figure
53) and torque them as specified in Table 2.
PISTONS A N D RINGS
The pistons can be removed after removing
the cylinder block. With the pistons off, the
connecting rods can be inspected without
separating the crankcase halves.
Each piston has 3 rings. The top 2 rings are
compression rings, to prevent compression
blowby into the crankcase. The bottom ring is
an oil control ring, to keep excess oil out of the
combustion chamber. Some bikes have a
1 -piece oil control ring and some have a 3-piece
oil control ring consisting of 2 flat rails with an
expander in between.
1. Lightly mark the top of the piston with a
"I", "2", "3'' and
so that each will be
Property of www.SmallEngineDiscount.com - Not for Resale