Inspection Of Piston Outer Diameter; Inspection Of Cylinder Inner Diameter; Inspection Of Piston Clearance - TOHATSU MFS 4 Service Manual

Power Unit

19) Inspection of Piston Outer Diameter

1. Measure piston outer diameter between points specified.
Replace if it is less than specified value.
Piston Outer Diameter a : Standard value
58.960 mm (2.3213 in)
Measuring Point b :
7mm (0.28 in) upward from the bottom of piston skirt
Functional Limit :
58.90 mm (2.3189 in)

20) Inspection of Cylinder Inner Diameter

Measure cylinder inner diameters (D1 - D6) at a, b and c in
1.
crank shaft directions d (D1, D3 and D5 respectively), and in
crank web directions e (D2, D4 and D6 respectively). Replace
cylinder block if the inner diameters are over specified value.
Cylinder Inner Diameter (D1 - D6) : Standard value
59.00 mm (2.3228 in)
Functional Limit :
59.07 mm (2.3256 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 Limit :
D1—D5 (Direction d)
D2—D6 (Direction e)
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 (Measuring Point a)
D6—D5 (Measuring Point c)
Functional Limit :
0.06 mm (0.0024 in)

21) 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 :
0.020 - 0.055 mm (0.00079 - 0.00217 in)
Functional Limit :
0.150 mm (0.00591 in)
5-30
a
D2
D4
D6
a 5mm d Crank Shaft Direction
(0.2in)
b 30mm e Crank Web Direction
(1.2in)
c 60mm
(2.4in)
b
D1
a
b
D3
c
D5
d
e
4st 4/5/6 2011