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F25C SERVICE MANUAL 290539 6D5-28197-5F-11...
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NOTICE This manual has been prepared by Yamaha primarily for use by Yamaha dealers and their trained mechanics when performing maintenance procedures and repairs to Yamaha equipment. It has been written to suit the needs of persons who have a basic understanding of the mechanical and electrical concepts and procedures inherent in the work, for without such knowledge attempted repairs or service to the equipment could render it unsafe or unfit for use.
Contents General information INFO Specifications SPEC Periodic checks and adjustments Fuel system FUEL Power unit POWR Lower unit LOWR Bracket unit BRKT – Electrical systems ELEC Troubleshooting TRBL SHTG Index...
INFO General information How to use this manual ................. 1-1 Manual format.................... 1-1 Symbols..................... 1-2 Safety while working..................1-3 Fire prevention................... 1-3 Ventilation....................1-3 Self-protection ................... 1-3 Parts, lubricants, and sealants ..............1-3 Good working practices ................1-4 Disassembly and assembly ............... 1-4 Identification....................1-5 Applicable models ..................1-5 Serial number ....................
INFO General information How to use this manual Manual format The format of this manual has been designed to make service procedures clear and easy to under- stand. Use the information below as a guide for effective and quality service. 1 Parts are shown and detailed in an exploded diagram and are listed in the components list.
Parts, lubricants, and sealants Use only genuine Yamaha parts, lubricants, and sealants or those recommended by Yamaha, when servicing or repairing the out- board motor. Ventilation Gasoline vapor and exhaust gas are heavier than air and extremely poisonous.
Safety while working Disassembly and assembly 6. Keep a supply of clean, lint-free cloths for wiping up spills, etc. 1. Use compressed air to remove dust and dirt during disassembly. Good working practices Special service tools 2. Apply engine oil to the contact surfaces Use the recommended special service tools of moving parts before assembly.
INFO General information Identification Propeller selection Applicable models The performance of a boat and outboard motor will be critically affected by the size This manual covers the following models. and type of propeller you choose. Propellers Applicable models greatly affect boat speed, acceleration, engine life, fuel economy, and even boating F25CMH, F25CM and steering capabilities.
Identification / Propeller selection / Predelivery checks a Propeller diameter (in inches) b Propeller pitch (in inches) CAUTION: c Propeller type (propeller mark) This is a 4-stroke engine. Never use pre- mixed fuel. Selection When the engine speed is at the full throttle operating range (5,000–6,000 r/min), the Checking the engine oil level ideal propeller for the boat is one that pro-...
INFO General information Checking the outboard motor mounting height 1. Check that the anti-cavitation plate is between the bottom of the boat and a maximum of 25 mm (1 in) a below it. If the mounting height is too high, cavita- tion will occur and propulsion will be reduced.
Predelivery checks Checking the steering system Checking the gear shift and throttle 1. Check the steering friction for proper operation adjustment. 1. Check that the gear shift operates smoothly when the remote control lever or shift lever is shifted from neutral to for- ward or reverse.
INFO General information Checking the engine stop lanyard Checking the cooling water pilot switch holes 1. Check that the engine turns off when the 1. Check that cooling water is discharged engine stop lanyard switch is pushed or from the cooling water pilot holes. the engine stop lanyard is pulled from the engine stop lanyard switch.
Predelivery checks Break-in During the test run, perform the break-in operation in the following three stages. 1. One hour a at 2,000 r/min or at approxi- mately half throttle 2. One hour b at 3,000 r/min or 3/4 throttle and 1 minute out of every 10 at full throt- 3.
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INFO General information — MEMO — 1-11 6D55F11...
SPEC Specifications Maintenance specification Power unit Model Item Unit F25CMH F25CM Power unit Minimum compression 810 (8.1, 115) (*1) pressure (kgf/cm , psi) (*2) Lubrication oil pressure 80 (0.8, 11) at engine idle speed (kgf/cm , psi) Cylinder heads Warpage limit mm (in) 0.10 (0.0039) (lines indicate straightedge...
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Maintenance specification Model Item Unit F25CMH F25CM Piston rings Top ring Dimension B mm (in) 1.17–1.19 (0.0461–0.0469) Dimension T mm (in) 2.25–2.45 (0.0885–0.0965) End gap mm (in) 0.15–0.30 (0.0059–0.0118) Side clearance mm (in) 0.02–0.06 (0.0008–0.0024) Oversize diameter mm (in) 65.250 (2.5689) mm (in) 65.500 (2.5787) 2nd ring...
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SPEC Specifications Model Item Unit F25CMH F25CM Valves Valve clearance (cold) Intake mm (in) 0.15–0.25 (0.006–0.010) Exhaust mm (in) 0.25–0.35 (0.010–0.014) Head diameter (A) Intake mm (in) 31.90–32.10 (1.256–1.264) Exhaust mm (in) 25.90–26.10 (1.020–1.028) Face width (B) Intake mm (in) 1.84–2.97 (0.072–0.117) Exhaust mm (in)
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Maintenance specification Model Item Unit F25CMH F25CM Crankcase Crankshaft main journal oil mm (in) 0.012–0.044 (0.0005–0.0017) clearance Crankcase main journal bearing thickness Blue mm (in) 1.498–1.502 (0.0590–0.0591) Black mm (in) 1.494–1.498 (0.0588–0.0590) Brown mm (in) 1.490–1.494 (0.0587–0.0588) Oil pump Type Trochoid Outer rotor-to-housing mm (in)
SPEC Specifications Tightening torques Specified torques Tightening torques Part to be tightened Thread size N·m kgf·m ft·lb Fuel system Fuel pump mounting bolt Fuel pump screw Carburetor bracket bolt Throttle link rod screw Power unit Power unit mounting bolt 15.5 Apron bolt Start-in-gear protection cable bolt Manual starter roller bolt...
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Tightening torques Tightening torques Part to be tightened Thread size N·m kgf·m ft·lb Lower unit Gear oil drain screw — Gear oil check screw — Lower case mounting bolt 27.3 Cooling water inlet cover screw Propeller nut 25.1 Propeller shaft housing bolt Pinion nut 36.9 Bracket unit...
SPEC Specifications General torques This chart specifies tightening torques for standard fasteners with a standard ISO thread pitch. Tightening torque specifications for special components or assemblies are provided in applicable sections of this man- ual. To avoid warpage, tighten multi-fastener assemblies in a crisscross fashion and pro- gressive stages until the specified torque is reached.
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Periodic checks and adjustments Special service tools ..................3-1 Maintenance interval chart................3-2 Top cowling ....................3-3 Checking the top cowling................3-3 Fuel system ....................3-3 Checking the fuel joint and fuel hoses (fuel joint-to-carburetor) ....3-3 Checking the fuel filter ................3-3 Power unit.......................
Periodic checks and adjustments Top cowling Checking the top cowling 1. Check the fitting by pushing the cowling with both hands. Adjust if necessary. Fuel system Checking the fuel joint and fuel hoses (fuel joint-to-carburetor) S6D53010 1. Check the fuel hose connections and fuel 2.
Top cowling / Fuel system / Power unit NOTE: Be sure not to spill any fuel when removing the fuel filter cup. Power unit Checking the engine oil 1. Place the outboard motor in an upright position. 2. Remove the engine oil dipstick, wipe it 3.
Periodic checks and adjustments 7. Turn the engine off, and then check the Oil filter: oil level and correct it if necessary. 18 N·m (1.8 kgf·m, 13.3 ft·lb) Replacing the oil filter 1. Drain the engine oil. 5. Pour the specified amount of the recom- mended engine oil into the oil filler hole.
Power unit 5. Install the spark plugs, tighten them fin- NOTE: ger tight, then to the specified torque The valve system of this model will not be using a spark plug wrench. damaged even if the timing belt breaks. Spark plug: 17 N·m (1.7 kgf·m, 12.5 ft·lb) Timing belt slack a: Within 13 mm (0.5 in)
Periodic checks and adjustments 4. Check the thermostat valve opening at 3. Check for water flow at the cooling water specified water temperatures. pilot holes. If there is no water flow, Replace if out of specification. check the cooling water passages inside the outboard motor.
Power unit / Control system 5. Operate the throttle cam to check that the throttle valve fully opens and fully closes. Adjusting the throttle cables (tiller handle model) 1. Turn the throttle grip to the fully open position. S6D53210 2. Loosen the locknut 1, and then turn the adjusting nut 2 to adjust the throttle Adjusting the throttle cable cable 3.
Periodic checks and adjustments 5. Check the throttle cable for smooth oper- ation and, if necessary, repeat steps 1–4. Checking the gear shift operation (tiller handle model) 1. Check that the gear shift operates smoothly when shifting it from neutral to forward or reverse.
Control system 3. Turn the throttle stop screw 2 in direc- NOTE: tion a or b until the specified engine If the starter rope cannot be pulled out, the idle speed is obtained. start-in-gear protection is working correctly. 3. Shift the remote control lever or shift lever to neutral.
Periodic checks and adjustments 4. Check that the a is specified timing on the flywheel magnet. Lower unit Checking the gear oil level Ignition timing at engine idle speed: 1. Fully tilt the outboard motor down. BTDC 8.5° 2. Remove the check screw 1, and then Bracket check the gear oil level in the lower case.
Control system / Bracket / Lower unit Changing the gear oil Checking the lower unit for air 1. Tilt the outboard motor up slightly. leakage 1. Remove the check screw 1, and then 2. Place a drain pan under the drain screw install the special service tool.
Periodic checks and adjustments General Checking the anodes 1. Check the anodes for scales, grease, or oil. Clean if necessary. S6D53240 È CAUTION: Do not oil, grease, or paint the anodes, otherwise they will be ineffective. S6D53290 È Tiller handle model 2.
FUEL Fuel system Special service tools ..................4-1 Hose routing ....................4-2 Fuel hoses and fuel filter................4-3 Fuel pump ....................... 4-4 Checking the fuel pump................4-5 Disassembling the fuel pump ..............4-5 Checking the diaphragms and valves............4-6 Assembling the fuel pump ................. 4-6 Checking the fuel joint ................
FUEL Fuel system Fuel hoses and fuel filter Part name Q’ty Remarks Fuel joint M6 × 25 mm Bolt Fuel hose M8 × 14 mm Bolt Bracket Fuel filter Fuel filter element O-ring Not reusable Fuel hose Fuel hose Fuel pump O-ring Not reusable Bracket...
Fuel hoses and fuel filter / Fuel pump Fuel pump Part name Q’ty Remarks ø5 × 43 mm Screw Cover Gasket Not reusable Diaphragm Not reusable Fuel pump body 2 assembly Plunger Spring Fuel pump body 1 Spring Diaphragm 6D55F11...
FUEL Fuel system Checking the fuel pump 6. Apply the specified positive pressure and check that there is no air leakage. Disas- 1. Place a drain pan under the fuel hose semble the fuel pump if necessary. connections, and then disconnect the fuel hoses from the fuel pump.
Fuel pump 3. Turn fuel pump body 1 2 approximately 90°, and then push down on the plunger several times to make sure that the pin does not come out. 3. Slowly let up on the plunger and dia- phragm, and then remove them. Checking the diaphragms and valves 1.
FUEL Fuel system Checking the fuel joint 1. Visually check the fuel hose connector for cracks or damage. 2. Connect the special service tool at the outlet of fuel hose connector. 3. Apply the specified pressure to check that the pressure is maintained for 10 seconds.
Fuel pump / Carburetor unit Carburetor unit Part name Q’ty Remarks M6 × 25 mm Bolt Fuel hose Plastic tie Not reusable Blowby hose M6 × 100 mm Bolt Intake silencer Joint Seal O-ring Not reusable Plate Bracket O-ring Not reusable Spacer Carburetor 6D55F11...
FUEL Fuel system Carburetor Part name Q’ty Remarks Throttle link rod ø4 × 5 mm Screw ø4 × 10 mm Screw Retainer Prime Start O-ring Not reusable ø4 × 10 mm Screw Cover Gasket Not reusable Throttle stop screw Spring Pilot screw O-ring Not reusable...
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Carburetor Part name Q’ty Remarks Carburetor body Float chamber Gasket Not reusable Plunger rod Plunger Spring Circlip Ball Drain screw ø4 × 13 mm Screw ø4 × 7 mm Screw Float Needle valve Main jet Main nozzle Plug Pilot jet 4-10 6D55F11...
FUEL Fuel system Removing the carburetor 1. Remove the manual starter. 2. Disconnect the throttle link rod and Prime Start connectors. 3. Disconnect the fuel hose. 4. Disconnect the blowby hose 1. CAUTION: • Direct the compressed air downward, otherwise cleaning solvent may be blown into your eyes or small parts of the carburetor may be blown off.
Carburetor Prime Start plunger extended length a (reference data): 10.7–15.4 mm (0.42–0.61 in) Time (min) Length (mm [in]) 10.7 (0.42) 12.6 (0.50) 14.1 (0.56) 14.8 (0.58) 15.3 (0.60) NOTE: • The float should be resting on the needle 15.4 (0.61) valve 1, but not compressing it.
FUEL Fuel system 2. Install the needle valve 5, float 6, float pin 7, and screw 8 as shown, and then the check the float for smooth operation. NOTE: For remote control models, the throttle cam S6D54120 cannot be turned unless the remote control lever is shifted to forward.
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Carburetor NOTE: • To increase the idle speed, turn the throttle stop screw in direction a. • To decrease the idle speed, turn the throttle stop screw in direction b. Engine idle speed: 925–1,025 r/min 4-14 6D55F11...
POWR Power unit Special service tools ..................5-1 Power unit....................... 5-3 Checking the compression pressure ............5-3 Checking the oil pressure ................5-3 Checking the valve clearance..............5-4 Disassembling the manual starter ............5-13 Checking the spiral spring ............... 5-13 Measuring the starter rope ..............5-13 Assembling the manual starter ..............5-13 Installing the starter rope .................5-14 Removing the timing belt and sprockets..........
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Cylinder block ....................5-33 Disassembling the cylinder block ............5-36 Checking the balancer................5-37 Checking the piston diameter ..............5-37 Checking the cylinder bore ..............5-37 Checking the piston clearance ..............5-38 Checking the piston rings ................5-38 Checking the piston ring grooves ............5-39 Checking the piston ring side clearance..........
POWR Power unit Power unit 5. If the compression pressure is below specification and the compression pres- Checking the compression pressure sure for each cylinder is unbalanced, add 1. Start the engine, warm it up for 5 min- a small amount of engine oil to the cylin- utes, and then turn it off.
Power unit Checking the valve clearance 7. Check the intake and exhaust valve clearances for cylinder #2. Adjust if out of 1. Remove the manual starter. specification. 2. Remove the fuel pump 1. 3. Disconnect the ignition coil connectors and spark plug caps 2 and remove the spark plugs and cylinder head cover 3.
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POWR Power unit 8. Loosen the rocker arm locknut 4, and then turn the adjusting screw 5 until the specified valve clearance is obtained. S6D55100 NOTE: • To decrease the valve clearance, turn the adjusting screw in direction f. • To increase the valve clearance, turn the adjusting screw in direction g.
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Power unit Part name Q’ty Remarks M5 × 13 mm Bolt Washer Clip Start-in-gear protection cable M6 × 25 mm Bolt Manual starter M6 × 12 mm Bolt Power unit Dipstick Dowel M6 × 14 mm Bolt Gasket Not reusable M8 ×...
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POWR Power unit Part name Q’ty Remarks M8 × 12 mm Bolt Starter pulley Washer Flywheel magnet Spacer M5 × 25 mm Bolt Stator coil Woodruff key Woodruff key Drive sprocket Driven sprocket Pulser coil M5 × 16 mm Bolt Washer M10 ×...
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Power unit m (0.5 kgf m, 3.7 ft m (0.8 kgf m, 5.9 ft • • • • • • 23 24 m (0.5 kgf m, 3.7 ft • • • S6D55040 Part name Q’ty Remarks Ignition coil M6 × 30 mm Bolt Holder Grommet...
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POWR Power unit m (0.5 kgf m, 3.7 ft m (0.8 kgf m, 5.9 ft • • • • • • 23 24 m (0.5 kgf m, 3.7 ft • • • S6D55040 Part name Q’ty Remarks CDI unit Bracket M5 ×...
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Power unit Part name Q’ty Remarks M6 × 55 mm Bolt Washer Throttle control lever Spacer Throttle cam M6 × 10 mm Bolt Bracket M6 × 25 mm, Remote control model Bolt Washer Remote control model Shift link lever Remote control model Collar Remote control model Shift link rod...
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POWR Power unit m (0.8 kgf m, 5.9 ft • • • m (0.3 kgf m, 2.2 ft • • • 15 N m (1.5 kgf m, 11.1 ft • • • S6D55020 Part name Q’ty Remarks M6 × 30 mm Bolt Washer Roller...
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Power unit m (0.8 kgf m, 5.9 ft • • • m (0.3 kgf m, 2.2 ft • • • 15 N m (1.5 kgf m, 11.1 ft • • • S6D55020 Part name Q’ty Remarks Bolt Drive plate Spring Sheave drum Cartridge spring Spring washer...
POWR Power unit Disassembling the manual starter Measuring the starter rope 1. Remove the lock cam retainer, and then 1. Measure the starter rope length. Replace remove the lock cam base plate 1 and if the length is out of specification. lock cam 2.
Power unit 3. Install the drive pawls 4. 3. Turn the sheave drum clockwise until the rope hole a and manual starter roller b 4. Install the spring 5 and drive plate 6, are aligned. Hold the sheave drum in this and then tighten the bolt 7 to the speci- position.
POWR Power unit 5. Pull the manual starter handle several times to check that the sheave drum turns smoothly and to check the starter rope for slack. Repeat steps 2–4 if nec- essary. NOTE: When checking the manual starter operation, pull the manual starter handle while pushing the start-in-gear protection lock cam so that it 3.
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Power unit 6. Disconnect the charge coil connectors CAUTION: and power bobbin connectors, and remove the stator coil 2. Apply force in the direction of the arrows shown to prevent the flywheel holder from slipping off easily. Flywheel holder: 90890-06522 5.
POWR Power unit Checking the timing belt and sprockets 1. Check the interior and exterior of the tim- ing belt for cracks, damage, or wear. Replace if necessary. 2. Check the drive sprocket and driven sprockets for cracks, damage, or wear. Replace if necessary.
Power unit NOTE: Do not turn the drive sprocket counterclock- wise, otherwise the valve system may be damaged. 6. Install the stator coil, and connect the charge coil connectors and power bobbin connectors. 7. Install the Woodruff key, then the fly- Universal clutch holder: wheel magnet.
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POWR Power unit 5. Remove the apron 1, and then remove the power unit by removing the bolts 2. 6. Remove the flywheel magnet, then the woodruff key. 5-19 6D55F11...
Power unit / Cylinder head Cylinder head Part name Q’ty Remarks Cylinder head Gasket Not reusable Dowel M9 × 95 mm Bolt M6 × 25 mm Bolt O-ring Not reusable O-ring Not reusable O-ring Not reusable Oil pump assembly M6 × 35 mm Bolt Gasket Not reusable...
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POWR Power unit Part name Q’ty Remarks Cover M5 × 12 mm Bolt Anode Grommet Spark plug 5-21 6D55F11...
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Cylinder head Part name Q’ty Remarks Exhaust valve Intake valve Valve spring seat Valve seal Not reusable Valve spring Valve spring retainer Valve cotter Rocker arm assembly Rocker arm retainer M8 × 30 mm Bolt Stopper guide Tensioner Rocker arm shaft Retaining bolt Gasket Not reusable...
POWR Power unit Removing the cylinder head 1. Remove the cylinder head cover. 2. Remove the cylinder head bolts in the sequence shown. & ± S6D55450 6. Remove the intake and exhaust valves. CAUTION: Do not scratch or damage the mating sur- faces of the cylinder head and cylinder block.
Cylinder head Checking the valve springs Valve margin thickness a: 1. Measure the valve spring free length a. Intake: 0.8 mm (0.0315 in) Replace if below specification. Exhaust: 0.9 mm (0.0354 in) 3. Measure the valve stem diameter b. Replace if out of specification. Valve spring free length a: 39.85 mm (1.5689 in) 2.
POWR Power unit Checking the valve guides Valve guide remover/installer: NOTE: 90890-06801 Before checking the valve guide make sure that the valve stem diameter is within specifi- 2. Install a new valve guide 2 by striking cation. the special service tool from the cam- shaft side until the valve guide clip 3 1.
Cylinder head 4. Measure the valve guide inside diameter. Valve guide inside diameter: Intake and exhaust: 5.500–5.512 mm (0.2165–0.2170 in) Checking the valve seat 1. Eliminate carbon deposits from the valve with a scraper. 2. Apply a thin, even layer of Mechanic’s blueing dye (Dykem) onto the valve seat.
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POWR Power unit 2. Cut the surface of the valve seat with a 45° cutter by turning the cutter clockwise until the valve seat face has become smooth. 60˚ S69J5890 b Previous contact width 5. Use a 45° cutter to adjust the contact width of the valve seat to specification.
Cylinder head 7. If the valve seat contact area is too nar- CAUTION: row and situated near the top edge of the valve face, use a 30° cutter to cut the top Do not get the lapping compound on the edge of the valve seat.
POWR Power unit Checking the camshaft 1. Measure the cam lobe. Replace if out of specification. Camshaft journal diameter c: 36.925–36.945 mm (1.4537–1.4545 in) Camshaft journal diameter d: Cam lobe a: 36.935–36.955 mm Intake and exhaust: (1.4541–1.4549 in) 30.834–31.034 mm Cylinder head journal inside (1.2139–1.2218 in) diameter e:...
Cylinder head S6D55560 S6D55570 Clearance a: 0.09–0.15 mm (0.0035–0.0059 in) Cylinder head warpage limit: Clearance b: 0.10 mm (0.0039 in) Within 0.12 mm (0.047 in) Clearance c: Checking the oil pump 0.03–0.08 mm (0.0012–0.0031 in) 1. Measure the oil pump rotor clearances as shown.
POWR Power unit 2. Install the valve 2, valve spring seat 3, 4. Lightly tap the valve spring retainer with valve spring 4, and valve spring retainer a plastic hammer to set the valve cotter 5 in the sequence shown, and then securely.
Cylinder head S6D55660 Rocker arm shaft bolt: 18 N·m (1.8 kgf·m, 13.3 ft·lb) Installing the oil pump Installing the rocker arm shaft 1. Install the oil pump 1 by aligning the oil pump drive shaft a with the camshaft pin assembly 1.
POWR Power unit Cylinder block Part name Q’ty Remarks Oil filter Union bolt Exhaust cover Holder M6 × 35 mm Bolt Thermostat cover Gasket Not reusable Thermostat Gasket Not reusable M8 × 35 mm Bolt Engine hanger Filter Steel Gasket Not reusable Plug Steel...
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Cylinder block Part name Q’ty Remarks Balancer piston Cover O-ring Not reusable M6 × 20 mm Bolt M8 × 82 mm Bolt M6 × 35 mm Bolt Crankcase Main bearing Bolt Connecting rod assembly Connecting rod bearing Oil seal Not reusable Balancer rod Crankshaft Oil seal...
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POWR Power unit Part name Q’ty Remarks Cylinder block Piston ring assembly Piston Piston pin Clip Not reusable 5-35 6D55F11...
Cylinder block Disassembling the cylinder block 1. Remove thermostat cover exhaust cover by removing the bolts in the sequence shown. S6D55730 5. Remove the crankcase bolts in the 2. Remove the oil filter. sequence shown. S6D55760 NOTE: Be sure to clean up any oil spills. 6.
POWR Power unit 8. Remove the piston pin clips 4 and pis- Piston diameter a: ton pin, and then remove the piston. 64.950–64.965 mm (2.5571–2.5577 in) Measuring point b: 2.0 mm (0.08 in) up from the bottom of the piston skirt Oversize piston diameter: Oversize 1st: 65.200–65.215 mm...
Cylinder block 3. Check the piston ring end gap d at the Out-of-round limit: specified measuring point. Replace if out (measuring point a) –D of specification. (measuring point c) –D 0.05 mm (0.0020 in) Checking the piston clearance 1. Replace the piston and piston rings as a set or the cylinder block, or all parts if out of specification.
POWR Power unit Checking the piston ring grooves Piston ring side clearance: 1. Measure piston ring grooves. Top ring a: Replace the piston if out of specification. 0.02–0.06 mm (0.0008–0.0024 in) 2nd ring b: 0.02–0.06 mm (0.0008–0.0024 in) Oil ring c: 0.04–0.18 mm (0.0016–0.0070 in) Checking the piston pin boss bore...
Cylinder block Checking the connecting rod small end inside diameter 1. Measure the connecting rod small end inside diameter a. Replace the connect- ing rod if out of specification. S6D55810 Connecting rod small end inside diameter a: 15.985–15.998 mm S6D55820 (0.6293–0.6298 in) Crankshaft journal diameter a: Checking the connecting rod big end...
POWR Power unit Checking the crankpin oil clearance 1. Clean the bearings and the connecting rod. 2. Install the upper bearing into the con- necting rod 1 and the lower bearing into the connecting rod cap 2. NOTE: • Install the connecting rod bearings in their NOTE: original positions.
Cylinder block 6. Remove the connecting rod cap and Connecting rod measure the width of the compressed Bearing color b mark a Plastigauge (PG-1) on each crankpin. Blue Replace the connecting rod bearing if out of specification. Black Brown Checking the crankshaft main journal oil clearance 1.
POWR Power unit 4. Put a piece of Plastigauge (PG-1) on each main journal parallel to the crank- shaft. Crankshaft main journal oil clearance: 0.012–0.044 mm NOTE: (0.0005–0.0017 in) Do not put the Plastigauge (PG-1) over the oil hole in the main journals of the crankshaft. Selecting the crankshaft main bearing 1.
Cylinder block Assembling the pistons and cylinder block 45˚ 45˚ 1. Assemble the piston 1, connecting rod 2, piston pin 3, and piston pin clips 4. #1,#4 S6D55900 CAUTION: Do not scratch the pistons or break the piston rings. NOTE: After installing the piston rings, check that they move smoothly.
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POWR Power unit 5. Install the piston with the “UP” mark on the piston crown facing towards the fly- wheel magnet. NOTE: Apply engine oil to the side of the pistons and NOTE: piston rings before installation. Apply engine oil to the inner oil seals before installation.
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Cylinder block 10. Install half of the main bearings into the 1–6 Crankcase bolt (M8): crankcase. 1st: 15 N·m (1.5 kgf·m, 11.1 ft·lb) NOTE: 2nd: 30 N·m (3.0 kgf·m, 22.1 ft·lb) • Install the main bearings in their original 7–B Crankcase bolt (M6): positions.
POWR Power unit 16. Before installing the oil filter, be sure to supply engine oil to the oil passage h. S6D55A10 Exhaust cover bolt: S6D55990 1st: 6 N·m (0.6 kgf·m, 4.4 ft·lb) 17. Install the oil filter, and then tighten it to 2nd: 12 N·m (1.2 kgf·m, 8.9 ft·lb) the specified torque using the oil filter Thermostat cover bolt:...
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Cylinder block Cylinder head bolt (M9): 1st: 23 N·m (2.3 kgf·m, 17.0 ft·lb) 2nd: 46 N·m (4.6 kgf·m, 34.0 ft·lb) Cylinder head bolt (M6): 1st: 6 N·m (0.6 kgf·m, 4.4 ft·lb) 2nd: 12 N·m (1.2 kgf·m, 8.9 ft·lb) 2. Install the cylinder head cover, and then tighten the bolts.
POWR Power unit 6. Connect the blowby hose 7. 7. Adjust the valve clearance. Valve clearance: Intake: 0.15–0.25 mm (0.006–0.010 in) Exhaust: 0.25–0.35 mm (0.010–0.014 in) NOTE: For adjustment procedures, see “Checking S6D55A50 the valve clearance”. 7. Connect the throttle cable 8 and shift cable 9 (remote control model), or throt- Installing the power unit tle cables 0 (tiller handle model), and...
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Cylinder block 10. Install the flywheel magnet. 12. Install all parts removed during disas- sembly. CAUTION: Apply force in the direction of the arrows shown to prevent the flywheel holder from slipping off easily. NOTE: Apply engine oil to the flywheel magnet nut before installation.
LOWR Lower unit Special service tools ..................6-1 Lower unit ....................... 6-4 Removing the lower unit ................6-7 Removing the water pump................. 6-7 Checking the water pump................6-8 Propeller shaft housing ................. 6-9 Removing the propeller shaft housing assembly........6-11 Disassembling the propeller shaft assembly ...........6-11 Disassembling the propeller shaft housing..........
LOWR Lower unit Shimming plate 90890-06701 Backlash indicator 90890-06706 Magnet base plate 90890-07003 Dial gauge set 90890-01252 Magnet base B 90890-06844 6D55F11...
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Special service tools / Lower unit Lower unit Part name Q’ty Remarks Lower unit Check screw Gasket Not reusable Drain screw Adjusting nut Locknut Cooling water inlet cover M6 × 35 mm Bolt Washer Anode ø5 × 26 mm Screw M10 ×...
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LOWR Lower unit Part name Q’ty Remarks Collar Washer Cotter pin Not reusable Dowel 6D55F11...
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Lower unit Part name Q’ty Remarks Water tube L-transom model O-ring Not reusable L-transom model O-ring Not reusable S-transom model Water tube S-transom model O-ring Not reusable S-transom model M6 × 40 mm Bolt Extension plate Cover Water pump housing Insert cartridge O-ring Not reusable...
LOWR Lower unit 4. Loosen the locknut 3, and then remove Removing the lower unit the adjusting nut 4. 1. Drain the gear oil. 5. Loosen the bolts 5, and then remove the lower unit from the upper case. 2. Shift the remote control lever or shift lever to neutral, place a block of wood between the anti-cavitation plate and propeller to keep the propeller from turn-...
Lower unit Checking the water pump 1. Check the water pump housing for defor- mation. Replace if necessary. 2. Check the impeller and insert cartridge for cracks or wear. Replace if necessary. 3. Check the Woodruff key 1 and the key- way a in the drive shaft for wear.
LOWR Lower unit Propeller shaft housing Part name Q’ty Remarks Shift plunger Dog clutch Cross pin Spring Spring Propeller shaft Washer Reverse gear Reverse gear shim — O-ring Not reusable Ball bearing Not reusable O-ring Not reusable Propeller shaft housing Needle bearing Oil seal Not reusable...
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Propeller shaft housing Part name Q’ty Remarks M6 × 25 mm Bolt Shift rod bracket Shift rod plate O-ring Not reusable Oil seal housing Dowel Gasket Not reusable Shift rod 6-10 6D55F11...
Propeller shaft housing 2. Check the propeller shaft for bends or wear. Replace if necessary. 3. Measure the propeller shaft runout. Needle bearing attachment 8: 90890-06615 Driver rod L3 9: 90890-06652 S6D56510 Disassembling the oil seal housing Runout limit: 0.02 mm (0.0008 in) 1.
LOWR Lower unit Assembling the propeller shaft Needle bearing attachment 4: housing 90890-06611 1. Install the needle bearing into the propel- Driver rod L3 5: 90890-06652 ler shaft housing to the specified depth. Depth d: 13.0–13.5 mm (0.512–0.532 in) Depth e: 6.0–6.5 mm (0.236–0.256 in) 3.
Propeller shaft housing Needle bearing attachment 0: 90890-06608 Assembling the oil seal housing 1. Apply grease to new oil seals, and then install them into the oil seal housing to the specified depth. Ball bearing attachment 1: 90890-06635 Driver rod LS 2: 90890-06606 Depth a: 5.5–6.0 mm (0.217–0.236 in) 6-14...
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LOWR Lower unit Drive shaft and lower case Part name Q’ty Remarks Drive shaft Taper roller bearing assembly Not reusable Pinion shim — Sleeve Needle bearing Pinion Forward gear shim — Taper roller bearing assembly Not reusable Forward gear Lower case 6-15 6D55F11...
Drive shaft and lower case Removing the drive shaft 1. Remove the drive shaft assembly and pinion, and then pull out the forward gear. CAUTION: Do not reuse the bearing, always replace it with a new one. S68S6150 Drive shaft holder 3 1: 90890-06517 Bearing separator 1: 90890-06534 Disassembling the drive shaft Disassembling the lower case...
LOWR Lower unit 2. Remove the drive shaft bearing outer Checking the drive shaft race, shim(s), and drive shaft sleeve. 1. Check the drive shaft for bends or wear. Replace if necessary. 2. Measure the drive shaft runout. NOTE: Install the claws as shown. S6D56520 Stopper guide plate 3: 90890-06501 Runout limit: 0.5 mm (0.020 in)
Drive shaft and lower case Depth c: CAUTION: 185–186 mm (7.283–7.323 in) Add or remove shim(s), if necessary, if replacing the forward gear or lower case. 2. Install the sleeve, original shim(s), and drive shaft bearing outer race. Bearing outer race attachment 6: 90890-06625 Driver rod LL 7: 90890-06605 Assembling the forward gear...
LOWR Lower unit Installing the pinion 1. Install the forward gear, then the drive shaft assembly, pinion, and pinion nut, and then tighten the nut to the specified torque. S6D56260 Propeller shaft housing bolt: 11 N·m (1.1 kgf·m, 8.1 ft·lb) Installing the water pump and shift S68S6410 1.
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Drive shaft and lower case 5. Install the new O-ring 9 and insert car- tridge 0 into the pump housing A, and then apply grease to the inside of the insert cartridge. S6D56300 NOTE: • When installing the pump housing, apply grease to the inside of the housing, and then turn the drive shaft clockwise while pushing down the pump housing.
LOWR Lower unit 5. Install the trim tab 5 to its original posi- Installing the lower unit tion, and then tighten the trim tab bolt 6. 1. Set the remote control lever or shift lever to reverse. È S6D56310 É Lower case mounting bolt 2: S6D56320 37 N·m (3.7 kgf·m, 27.3 ft·lb)
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Drive shaft and lower case 8. Install the check screw and quickly install the drain screw. WARNING • Do not hold the propeller with your hands when loosening or tightening it. • Be sure to remove the clip from the engine stop lanyard switch.
Shimming Shimming 2. Install the pinion and pinion nut, and then tighten the nut to the specified torque. NOTE: • Shimming is not required when assembling Pinion nut: the original lower case and inner parts. 50 N·m (5.0 kgf·m, 36.9 ft·lb) •...
LOWR Lower unit 4. Calculate the pinion shim thickness (T3) Example: as shown in the examples below. If “T3” is 1.25 mm, then the pinion shim is 1.3 If “T3” is 1.75 mm, then the pinion shims are 0.7 and 1.1 mm. Selecting the forward gear shims 1.
Shimming Selecting the reverse gear shims 1. Install the ball bearing onto the propeller shaft housing. 2. Measure the bearing housing height (M2) as shown. S6D56400 NOTE: “F” is the deviation of the lower case dimen- sion from standard. The “F” mark a is stamped on the anode mounting surface of the lower case in 0.01 mm units.
LOWR Lower unit 3. Calculate the reverse gear shim thick- Example: ness (T2) as shown in the examples If “T2” is 1.05 mm, then the reverse gear below. shim is 1.0 mm. If “T2” is 1.20 mm, then the reverse gear shim is 1.1 mm.
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Shimming / Backlash 7. Remove the special service tools from the propeller shaft. 8. Apply a load to the reverse gear by installing the propeller 8 (without the spacer 9), the collar 0, then the washer A as shown. NOTE: Install the dial gauge so that the plunger a contacts the mark b on the backlash indica- NOTE:...
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LOWR Lower unit 10. Add or remove shim(s) if out of specifica- tion. Reverse gear Shim thickness backlash Less than To be decreased by (1.29 – M) × 0.49 0.92 mm (0.0362 in) More than To be increased by (M – 1.29) × 0.49 1.65 mm (0.0650 in) M: Measurement Available shim thicknesses:...
BRKT Bracket unit Tiller handle ....................7-1 Assembling the tiller handle............... 7-3 Bottom cowling ....................7-4 Upper case, steering arm ................7-6 Draining the engine oil................7-10 Disassembling the oil pan................7-10 Checking the oil strainer ................7-10 Checking the oil pan ................7-10 Assembling the oil pan ................7-10 Removing the steering arm ..............
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BRKT Bracket unit Tiller handle Part name Q’ty Remarks Throttle cable Engine stop lanyard switch Grommet Shift link rod Shift lever Washer Wave washer Collar M6 × 30 mm Bolt Self-locking nut Cable guide Bushing Steering bracket Plastic washer 6D55F11...
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Tiller handle Part name Q’ty Remarks Metal washer Wave washer Bushing Tiller handle bracket Throttle friction adjuster Throttle grip ø5 × 25 mm Screw Washer Spring Bushing Throttle shaft Friction piece M6 × 20 mm Bolt Plate Engine stop lanyard 6D55F11...
BRKT Bracket unit Assembling the tiller handle NOTE: 1. Install the engine stop lanyard switch 1 • Route the engine stop lanyard switch lead to the tiller handle bracket 2. Tighten the 9 and throttle cables 0 and A as shown. nut to the specified torque.
Tiller handle / Bottom cowling Bottom cowling Part name Q’ty Remarks Shift rod lever joint Remote control model M6 × 25 mm Bolt Bracket Start-in-gear protection lever Shift rod lever Shift rod Bottom cowling Rubber seal Grommet Grommet Remote control model Grommet Remote control model Grommet...
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BRKT Bracket unit Part name Q’ty Remarks Grommet Collar Water outlet Bolt Hook M6 × 20 mm Bolt Lever Bushing Bushing Wave washer Washer Cowling lock lever Grommet Tiller handle model Grommet Remote control model Cable guide Remote control model M6 ×...
Bottom cowling / Upper case, steering arm Upper case, steering arm Part name Q’ty Remarks Mount housing Rubber damper Rubber damper M10 × 80 mm Bolt M10 × 120 mm Bolt ø6 × 8 mm Screw Ground lead Grease nipple M8 ×...
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BRKT Bracket unit Part name Q’ty Remarks Bushing Straight key Bushing O-ring Not reusable Bushing Remote control model Washer Remote control model Steering hook Remote control model M8 × 20 mm Bolt Rubber seal 6D55F11...
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Upper case, steering arm Part name Q’ty Remarks Upper case ø5 × 15 mm Screw Baffle plate Dowel M8 × 30 mm Bolt Gasket M6 × 50 mm Bolt Washer Bracket Exhaust manifold Gasket Not reusable Oil pan Gasket Not reusable M14 ×...
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BRKT Bracket unit Part name Q’ty Remarks Gasket Not reusable Exhaust guide Oil seal Not reusable Grommet Anode Cover M5 × 12 mm Bolt Cover M6 × 20 mm Bolt Cooling water pipe Rubber seal M6 × 16 mm Bolt Oil strainer M6 ×...
Upper case, steering arm Draining the engine oil 2. Check the cooling water pipe for defor- mation or corrosion. Replace if neces- 1. Place a drain pan under the drain hole, sary. and then remove the drain bolt and let the oil drain completely.
BRKT Bracket unit 4. Install the cooling water pipe 4. 5. Install the oil pan 5 and bolts, and then tighten the bolts finger tight. 6. Install the exhaust manifold 6, seal, and bolts, and then tighten the bolts finger tight.
Upper case, steering arm 4. Tighten the lower mounting nuts 5 to the Installing the steering arm specified torque, then tighten the lower 1. Install the washer 1, bushing 2, and mounting nuts 7 to the specified torque. straight key 3 onto the steering arm 4. 2.
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BRKT Bracket unit Part name Q’ty Remarks Spring Tilt lock rod Tilt lever ø5 × 5 mm Screw Collar Circlip Tilt lock lever Bushing Bushing Tilt support bar Spring Pin 1 Pin 2 Tilt lock plate Tilt lock arm Collar 7-15 6D55F11...
Clamp brackets, swivel bracket 3. Install the tilt support bar A and pin B, Removing the clamp brackets and then insert the tilt lock lever C par- 1. Remove the tilt pin, and then remove the tially into the swivel bracket. clamp bracket bolt, clamp bracket nut, and collar.
BRKT Bracket unit 5. Install the screw G to the tilt lever E, Tilt stopper plate nut: and then install the circlip H to the pin 24 N·m (2.4 kgf·m, 17.7 ft·lb) Self-locking nut 1: 45 N·m (4.5 kgf·m, 33.2 ft·lb) Clamp bracket nut 4: 8 N·m (0.8 kgf·m, 5.9 ft·lb) 6.
– ELEC Electrical systems Special service tools ..................8-1 Checking the electrical components............8-2 Measuring the peak voltage ..............8-2 Measuring the lower resistance..............8-2 Electrical components................... 8-3 Front and aft views ..................8-3 Port and starboard views................8-4 Wiring diagram ..................8-5 Checking the ignition spark gap ..............8-7 Checking the spark plug caps ..............8-7 Checking the ignition coil................8-7...
– ELEC Electrical systems Special service tools Ignition tester 90890-06754 Digital circuit tester 90890-03174 Peak voltage adapter B 90890-03172 Test harness (2 pins) New: 90890-06868 Current: 90890-06768 Vacuum/pressure pump gauge set 90890-06756 6D55F11...
Special service tools / Checking the electrical components Checking the electrical Measuring the lower resistance When measuring a resistance of 10 Ω or less components with the digital circuit tester, the correct mea- Measuring the peak voltage surement cannot be obtained due to the internal resistance of the tester.
– ELEC Electrical systems Checking the ignition spark gap 1. Disconnect the spark plug caps from the spark plugs. 2. Connect a spark plug cap to the special service tool. 2. Measure the spark plug cap resistance. Replace if out of specification. S6D58040 Ignition tester: 90890-06754 3.
– ELEC Electrical systems Checking the oil pressure warning indicator 1. Connect a penlight battery (1.5 V) to the oil pressure warning indicator (LED). Replace if it does not light. CAUTION: Only use a penlight battery (1.5 V) when checking the LED. Other batteries (e.g., alkaline batteries or high-voltage batter- ies) will damage the diode.
TRBL SHTG Troubleshooting Power unit....................... 9-1 6D55F11...
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TRBL SHTG Troubleshooting NOTE: • Before troubleshooting the outboard motor, check the compression pressure, valve clearance, the mounting and rigging of the outboard motor, and the operation of the manual starter. Also, make sure that specified fuel has been used. •...
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Power unit Good spark? Check the fuel system. Check the ignition coil resis- tance. Good condition? Replace the ignition coil. Check the spark plug cap resis- tance and the spark plug caps for salt buildup. Repair or replace the spark plug Good condition? caps.
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TRBL SHTG Troubleshooting Good condition? Check the fuel system. Replace the CDI unit. Fuel system Check the fuel filter for clogs and the hoses for leaks. Repair or replace the defective Clogs or leaks? parts. Check the fuel pump dia- phragms.
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Power unit Symptom 2: Engine speed at wide open throttle is low, engine speed decreases, or engine stalls (poor acceleration or poor deceleration). Symptom 3: Engine speed not stable at low speeds. • Air vent screw on the fuel tank is open. •...
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TRBL SHTG Troubleshooting Within specification? Adjust the pilot screw. Disassemble the carburetor and check the internal parts for clogs, debris, or wear. Clogs, debris, Clean or replace the defective or wear? parts. Check the ignition system or lubrication system. 6D55F11...
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Power unit Lubrication system Check the engine oil level. Add engine oil to the correct At specified level? level. Check the oil pressure. Check the oil pump for debris or Within specification? oil leaks. Check the oil Debris or leaks? passage.
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Index Checking the crankshaft main journal oil clearance ..........5-42 Adjusting the throttle cable Checking the cylinder bore ....... 5-37 (remote control model)......3-8 Checking the cylinder head ...... 5-29 Adjusting the throttle cables Checking the diaphragms and valves..4-6 (tiller handle model) ........3-8 Checking the drive shaft ......
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Index Checking the propeller shaft housing..6-12 Checking the pulser coil......8-8 Fire prevention..........1-3 Checking the remote control cables Front and aft views ........8-3 (remote control model)......1-7 Fuel hoses and fuel filter ......4-3 Checking the rocker arms and Fuel pump........... 4-4 rocker arm shaft ........5-28 Fuel system ..........
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Index Parts, lubricants, and sealants....1-3 Wiring diagram ........... 8-5 Port and starboard views ......8-4 Power unit ......2-3 Predelivery checks........1-6 Propeller selection ........1-5 Propeller shaft housing .......6-9 Propeller size ..........1-5 Refacing the valve seat......5-26 Removing the carburetor ......4-11 Removing the clamp brackets....7-16 Removing the cylinder head .....5-23 Removing the drive shaft ......6-16 Removing the lower unit ......6-7...
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YAMAHA MOTOR CO., LTD. Printed in Japan Nov. 2003 – 0.4 × 1 CR Printed on recycled paper...
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