Yamaha XS750, Manual, Page: 49 / 154

b. Determine piston clearance
as
follows:
I
Minimum bore measurement
-
Maximum Diston measurement
=
Piston clearance
EXAMPLE:
68.02mm
-
67.97mm
=
.05mm
piston clearance
c. Piston ring/ring groove fit must have correct
clearance.
If
the piston and
ring
have already
been used, the ring must be removed and the
ring groove cleaned of carbon. The ringshould
then be reinstalled. Use a feeler gauge to meas-
0.04-0.08mm
0.03-0.07mm
(0.001
2-0.0028
in
.
)
(0.0016-0.003
in.)
Side clearance
ure the gap between the
ring
and the land.
2. Piston Ring
a.
The oversize top and middle ring sizes are
stamped on top of the ring.
Standard
Oversize
1
Oversize
2
Oversize 3
67.96mm
67.97
m
m
68.25mm
68.50mm
68.75mm
Oversize
2
Oversize 3
Oversize 4
0.50mm
0.75mm
1.00mm
b. The expander spacer of the bottom ring (oil
control ring) is color-coded t o identify sizes.
The color mark is painted on the expander
spacer.
Size Color
Oversize
1
Brown
Oversize
2
Oversize
3
Black
Oversize 4 Yellow
c. Push the ring into the bore and check end gap
clearance with
a
feeler gauge.
NOTE: The end
gap
on the expander spacer
of the oil control ring
is
unmeasureable. I f the
oil control ring rails show excessive gap, all
three components should be replaced.
Top/2nd ring 0.2~0.4mm
0.80mm
(.008~.016
in.)
(0.03
in.)
Oil control
0.2~0.9mm
Visual
(Rails)
H. Piston Pin
1. Apply a light film of oil to pin. Install in con-
necting rod small end. Check for play. There
should be no noticeable vertical play. If play
exists, check connecting rod small end for
wear. Replace pin and connecting rod as
re-
quired.
2.
The piston pin should have no noticeable free
play in piston.
If the piston pin is loose, re-
place the pin andlor the piston.
I. Crankshaft
1.
Crankshaft Run-Out
Support the crankshaft a t both ends on
V-blocks. Measure the amount of crankshaft
run-out on the main bearing journals with a
dial gauge while rotating crankshaft.