Yanmar 1GM User Manual page 99

SINGLE-CYLINDER ENGINES
93
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- Dial ga uge
,
3. Che ck all journals aga inst specifications (Ta ble 1) for
out-of-roundness and taper. Have the crankshaft
reground, ifnecessary, and install new undersize bearings.
5
If gear back lash is incorrect, rep lace the camshaft
and crankshaft gears.
Inspection
1. Clean the crankshaft thoroughly with solvent. Blow
out the oil passages with compressed air.
2. Check the ma in and connecting rod journals for wear,
scratches, grooves, scoring or cracks. Check the oil seal
contact surface for burrs, nicks or ot her sharp edges that
might damage a seal during installation.
NOTE
Unless precision measuring equipment is
available, have a machine shop perform
Step 3.
M AI N BEARINGS
The crankshaft is supported at each end by bush-
ing-type main bearings. The front main beari ng is located
in the crankcase and the rear main bearing is located in the
rem ovab le main bearing carrier. Thrust bearings located
at the front of the cra nkshaft control cran kshaft end play.
Refer to Figure 70 .
Remove the crankshaft as described in the previous sec-
tion for access to the main bearings and thrust washers.
Unless prec ision measuring equipment is available, have
a dealership or machine shop measure main bearing di-
mensions. Refe r to specifications in
Tab le I.
If bearing repl acement is necessary, have the main bear-
ings rep laced by a deal ership or machine shop. Make sure
the oil holes (B, Figure 76) in the main bearings align
with the oil passages in the crankcase an d main bearing
earner.
CAMS HAFT
Removal and Installation
I. Remove the fuel transfer pump (Figur e 80 ).
2. Remove {he crankshaft as previously described.
3. Prevent rotation of the camshaft gear by ho lding a
screwdriver or other tool against the camshaft bearing re-
taining screw (F igu re 81 ).
4 . Remove the camshaft gea r nut (A, Flgu re 82), fuel in-
jection pump cam (B) and camshaft gear (C) .
5. Position the engine so the valve lifters will not fall out
when the camshaft is withdrawn/removed.