Yamaha MA190, Service Manual

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56
4
Camshaft check
The camshaft is main driving part of the train
valve mechanism, which controls the intake
and exhaust valves opening and closing.
Feature: The shaft is equipped with cam and
journal which can control intake and exhaust.
When operating, camshaft operating face and
lifter will be badly rubbed from periodically
impacting and easily be damaged. So, the
camshaft shall be wearable and lubrication
well.
9
Visually inspect camshaft face and cam-
shaft height for damaged, and camshaft
and bearing for loosening and wearing,
replace as required.
9
Check camshaft for height dimension. If out
of the service limit, replace the camshaft.
Standard Service limit
IN lifter 23.98 mm 23.730 mm
EX lifter 27.88 mm 27.630 mm
9
Check inner diameter of the camshaft hole,
if less than the service limit, replace the
camshaft.
Standard Service limit
9.00–9.04 mm 9.090 mm
4-3 Engine
9
Remove connecting rod and measure
with plastic gauge.
9
If the clearance exceeds the service
limit, replace the connecting rod and
recheck the clearance.
Standard Service limit
0.019–0.049 mm 0.120 mm
Plastic feeler
Plastic feeler with scale