Honda Crf250l Service Manual

							9-8
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COOLING SYSTEM
WATER PUMP
MECHANICAL SEAL INSPECTION
Check the bleed hole [1] of the water pump for signs of
coolant leakage.
If water leaks through the bleed hole, replace the
mechanical seal (page 9-9).
If oil leaks through the bleed hole, replace the oil seal
(page 9-9).
Make sure that there are no continuous coolant leakage
from the bleed hole while operating the engine.
A small amount of weeping from the bleed hole is
normal.
REMOVAL
Drain the coolant (page 9-5).
Remove the bolts [1], drain bolt [2], sealing washer [3],
water pump cover [4] and O-ring [5].
Remove the right crankcase cover (page 12-4).
Hold the water pump shaft and remove the impeller [1]
and plain washer [2].
Remove the water pump shaft [1] from the right
crankcase cover.
[1]
[1][2]/[3]
[5][4]
[2]
[1]
[1] 
						

							9-9
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COOLING SYSTEM
Check the water pump shaft [1] for wear or damage,
replace it if necessary.
BEARING/MECHANICAL SEAL/OIL 
SEAL REPLACEMENT
Remove the water pump shaft bearings [1] using the
special tools.
[1]
MECHANICAL SEAL
OIL SEAL
BEARINGS
TOOLS:
[2] Remover weight 07741-0010201
[3] Bearing remover set, 12 mm 07936-1660101
[1]
[2]
[3] 
						

							9-10
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COOLING SYSTEM
Remove the mechanical seal [1] and oil seal [2] from
the right crankcase cover.
Apply grease to a new oil seal [1] lips.
Install the oil seal to the right crankcase cover as
shown.
Drive in a new
bearing squarely
with the marking side facing up.Drive in new bearings [1] into the right crankcase cover
using the special tools as shown.
After installing the bearing, lubricate it with engine oil.
Press a new mechanical seal [1] until it is fully seated to
the right crankcase cover using the hydraulic press and
special tool.
[1][2]
[1] 0 – 0.5 mm 
(0 – 0.02 in)
TOOLS:
[2] Driver
07749-0010000
[3] Attachment, 28 x 30 mm 07946-1870100
[4] Pilot, 12 mm 07746-0040200
[2]
[3]/[4][1]
TOOL:
[2] Oil seal driver, 30 x 36 mm 07HMF-KR10101
[2]
[1] 
						

							9-11
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COOLING SYSTEM
INSTALLATION
Apply engine oil to the water pump shaft [1] outer
surface.
Install the water pump s haft to the right crankcase
cover.
Install the plain washer [1] and impeller [2] to the water
pump shaft.
Hold the water pump shaft and tighten the water pump
impeller [1] to the specified torque.
Install the right crankcase cover (page 12-8).
Install a new O-ring [1] to the water pump cover [2].
Install the water pump cover.[1]
[2][1]
TORQUE: 10 N·m (1.0 kgf·m, 7 lbf·ft)
[1]
[2]
[1] 
						

							9-12
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COOLING SYSTEM
Install and tighten the bolts [1], drain bolt [2] and a new
sealing washer [3] securely.
Fill the recommended coolant and bleed the air (page
9-5).
RADIATOR RESERVE TANK
REMOVAL/INSTALLATION
Remove the right fuel tank shroud (page 2-4).
Place an approved container  under the radiator reserve
tank [1].
Disconnect the overflow hose [2] and siphon hose [3]
from the reserve tank.
Remove the bolts [4] and radiator reserve tank
Installation is in the reverse order of removal.
Fill the reserve tank wit h coolant (page 9-5).
FAN CONTROL RELAY
INSPECTION
Remove the left side cover (page 2-3).
Remove the dust cover [1]
Remove the fan control relay [2].
Connect a ohmmeter to the fan control relay [1]
terminals.
Connect a 12 V battery to the fan control relay terminals
as shown.
There should be continuity only when 12 V battery is
connected.
If there is no continuity when the 12 V battery is
connected, replace the fan control relay.
[1]
[2]
[3]
[2]
[1]
[4]
[3]
[2]
[1]
[1] 
						

							9-13
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COOLING SYSTEM
WATER PIPE
REMOVAL/INSTALLATION
Drain the coolant (page 9-5).
Remove the bolts [1] and water pipe [2].
Remove the O-rings [1] from the water pipe [2].
Installation is in the reverse order of removal.
 • Replace the O-ring with new ones.
Fill the system with the recommended coolant (page 9-
5).[2]
[1]
[1]
[2] 
						

							MEMO
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							10-1
10
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10. CYLINDER HEAD/VALVES
SERVICE INFORMATION ···························10-2
TROUBLESHOOTING·································10-2
COMPONENT LOCATION ··························10-3
CYLINDER COMPRESSION ··················\
·····10-4CYLINDER HEAD COVER ························· 10-4
CAMSHAFT················································· 10-6
ROCKER ARM ·········································· 10-11
CYLINDER HEAD ····································· 10-13 
						

							10-2
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CYLINDER HEAD/VALVES
CYLINDER HEAD/VALVESSERVICE INFORMATION
GENERAL
 • This section covers service of the cylinder head, valves, rocker arms and camshaft.
 • The camshaft and rocker arm service can be done with the engine installed in the frame. The cylinder head service requires engine removal.
 • Be careful not to damage the mating surfaces when removing  the cylinder head cover and cylinder head. Do not tap the cylinder
head cover and cylinder head too hard during removal.
 • When disassembling, mark and store the disassembled parts to  ensure that they are reinstalled in their original locations.
 • Clean all disassembled parts with cleaning solvent and dry them  by blowing them off with compressed air before inspection.
 • Camshaft and rocker arm lubricating oil is  fed through oil passage in the cylinder head (stud bolt hole) and camshaft holder.
Clean the oil passage before assembling them.
TROUBLESHOOTING
 • Engine top-end problems usually affect engine performance.  These problems can be diagnosed by a compression test, or by
tracing top-end noise with a s ounding rod or stethoscope.
 • If the performance is poor at low speeds, check for white smoke  in the crankcase breather hose. If the hose is smoky, check for
a seized piston rings.
Compression too low, hard starting or poor performance al low speed
 • Valves: – Incorrect valve adjustment
– Burned or bent valve
– Incorrect valve timing
– Weak valve spring
– Uneven valve seating
– Valve stuck open
 • Cylinder head: – Leaking or damaged cylinder head gasket
– Warped or cracked cylinder head
– Loose spark plug
 • Faulty cylinder, piston or piston rings (page 11-3).
Compression too high, over-heating or knocking
 • Excessive carbon build-up on piston head or combustion chamber
Excessive smoke
 • Worn valve stem or valve guide
 • Damaged stem seal
 • Faulty cylinder, piston or piston rings (page 11-3).
Excessive noise
 • Incorrect valve adjustment
 • Sticking valve or broken valve spring
 • Worn or damaged camshaft
 • Worn rocker arm and/or shaft
 • Worn rocker arm and valve stem end
 • Worn cam sprocket teeth
 • Worn and loose cam chain
 • Worn or damaged cam chain tensioner
 • Faulty cylinder, piston or piston rings (page 11-3).
Rough idle
 • Low cylinder compression
 • Faulty fuel system 
						

							10-3
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CYLINDER HEAD/VALVES
COMPONENT LOCATION
12 N·m (1.2 kgf·m, 9 lbf·ft)
45 N·m (4.6 kgf·m, 33 lbf·ft)
10 N·m (1.0 kgf·m, 7 lbf·ft)
4.2 N·m (0.4 kgf·m, 3.1 lbf·ft)