Inspection Of Pistons - TOHATSU EverRun MX50D2 Manual De Servicio

Power Unit
b
a
5-62
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18) Inspection of Pistons

1. Inspection of Piston Outer Diameter
Measure piston outer diameter, and replace the piston if
the outer diameter is less than the functional Limit.
2. Inspection of Piston Clearance
Calculate piston clearance, and if it is over the limit,
replace piston or any of piston rings, replace cylinder, or
use oversized piston.
3. Inspection of Piston Rings
1) Push a piston ring into the cylinder by using top surface
2) Use thickness gauge to measure piston ring gap.
Measurement Point b :
12 mm (0.47 in) above bottom end of piston skirt.
approximately 90 degrees from pin hole.
Standard Value a :
Standard Piston : 67.96 mm (2.6756 in)
Oversized Piston : 68.46 mm (2.6953 in)
Functional Limit a :
Standard Piston : 67.90 mm (2.673 in)
Oversized Piston : 68.40 mm (2.69 in)
Piston Clearance :
Standard Value : 0.08 - 0.12 mm (0.00315 - 0.00472 in)
Functional Limit :
0.21 mm (0.00827 in)
Calculation of Piston Clearance :
Cylinder Inner Diameter - Piston Outer
Diameter
Use the maximum value of the cylinder inner
diameter measured.
of a piston.
Replace piston ring if the gap is over specified value.
Thickness Gauge :
Commercially Available Item
Piston Ring End Gap : Standard Value
Top Ring
Second Ring
Functional Limit :
}
Top Ring
Second Ring
GB
0.22 - 0.37 mm
(0.009 - 0.015 in)
0.33 - 0.48 mm
(0.013 - 0.019 in)
1.0 mm
(0.00394 in)
2st X50D2 2011