Inspection Of Piston Outer Diameter; Inspection Of Cylinder Inner Diameter; Inspection Of Piston Clearance - TOHATSU MFS 60A Service Manual

Power Unit

27) Inspection of Piston Outer Diameter

1. Measure piston outer diameter between points specified.
Replace if the diameter is less than specified value.
Piston Outer Diameter a : Standard Value
69.97 mm (2.7547 in)
Measurement Points b :
9 mm (0.35 in) above piston skirt bottom
Functional Limit :
69.90 mm (2.7520 in)

28) Inspection of Cylinder Inner Diameter

Measure cylinder inner diameters (D1 to D6) at a, b and c
1.
in crankshaft directions d (D1, D3 and D5 respectively), and
in crank web directions e (D2, D4 and D6 respectively).
Cylinder Inner Diameters (D1 to D6) : Standard Value
70.00 mm (2.7559 in)
Functional Limit :
Replace if over 70.06 mm (2.7583 in).
Note : Measure at the maximum wear points.
2. Obtain taper through calculation described below. Replace
cylinder block if taper is over specified value.
Taper :
D1 – D5 (Measurement Point a)
D2 – D6 (Measurement Point c)
Functional Limit :
0.06 mm (0.0024 in)
3. Obtain out-of-roundness through calculation described
below. Replace cylinder block if out-of-roundness is over
specified value.
Out-of-roundness :
D2 – D1 (Direction d)
D6 – D5 (Direction e)
Functional Limit :
0.06 mm (0.0024 in)

29) Inspection of Piston Clearance

1. If piston clearance is over specified limit, replace cylinder
block, piston and piston rings as a set, or both.
Piston Clearance (Cylinder inside diameter –
Piston outside diameter):
0.020 to 0.055 mm (0.00079 to 0.00217 in)
Functional Limit :
0.150 mm (0.00591 in)
5-42
a
D1
D3
D5
a 15 mm (0.6 in)
b 35 mm (1.4 in)
c 55 mm (2.2 in)
b
D2
a
b
D4
c
D6
d
e
4st 60 2019