Power Unit - TOHATSU MFS25 Service Manual

1 Special Tools
.................................... 5-2
2 Parts Layout
.................................... 5-3
Engine ................................................... 5-3
Recoil Starter .......................................... 5-4
Magneto & ECU ....................................... 5-5
Electric Parts .......................................... 5-6
Fuel Pump, Fuel Rail, Vapor Separator ......... 5-8
Intake Manifold ....................................... 5-11
Cam Shaft & Oil Pump .............................. 5-12
Cylinder Head.......................................... 5-13
Intake Valve & Exhaust Valve ..................... 5-14
Cylinder ................................................ 5-15
Piston & Crankshaft ................................. 5-16
Top Cowl ................................................ 5-17
3 Inspection Items
........................... 5-18
1) Inspection of Compression Pressure......... 5-18
2) Inspection of Oil Pressure ..................... 5-19
3) Inspection of Valve Clearance ............... 5-20
4) Removing Power Unit ........................... 5-22
5) Removing Timing Belt and Pulley ............ 5-25
6) Inspection of Timing Belt ........................ 5-26
7) Installation of Pulley and Timing Belt......... 5-27
8) Removing Cylinder Head........................ 5-30
9) Inspection of Valve Spring ..................... 5-32
10) Inspection of Valve .............................. 5-33
11) Inspection of Valve Guide ..................... 5-33
12) Inspection of Valve Seat ........................ 5-34
13) Correction of Valve Seat ........................ 5-35
14) Inspection of Rocker Arm and Rocker Arm Shaft... 5-37
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Power Unit

15) Inspection of Cam Shaft .................. 5-38
16) Inspection of Cylinder Head ............... 5-39
17) Inspection of Oil Pump ..................... 5-40
18) Installation of Valves ........................ 5-41
19) Installation of Cam Shaft .................. 5-42
20) Installation of Rocker Arm Shaft ......... 5-42
21) Installation of Oil Pump ..................... 5-43
22) Installation of Cylinder Head............... 5-44
23) Disassembly of Cylinder Block............ 5-45
24) Inspection of Piston Outer Diameter ... 5-46
25) Inspection of Cylinder Inner Diameter... 5-46
26) Inspection of Piston Clearance ......... 5-46
27) Inspection of Piston Ring Side Clearance...... 5-47
28) Inspection of Piston Rings ............... 5-47
29) Inspection of Piston Pins .................. 5-48
30) Inspection of Connecting Rod Small End Inner Diameter 5-48
31) Inspection of Connecting Rod Big End Side Clearance 5-48
32) Inspection of Crankshaft .................. 5-49
33) Inspection of Crank Pin Oil Clearance ...... 5-50
34) Inspection of Crankshaft Main Journal Oil Clearance ... 5-51
35) Inner Diameter of Cylinder/Crank Case Bearing Holder (Inner Diameter Code)... 5-52
36) Thickness of Bearing (Color of Inner Diameter Code) ... 5-52
37) Assembling Piston and Connecting Rod ... 5-53
38) Installation of Power Unit .................. 5-57
39) Removing Recoil Starter .................. 5-59
40) Disassembly of Recoil Starter ............ 5-59
41) Inspection of Recoil Starter ............... 5-60
42) Installation of Recoil Starter ............... 5-61
5