Honda Crf250l Service Manual

							10-4
dummyhead
dummyhead
CYLINDER HEAD/VALVES
CYLINDER COMPRESSION
Warm the engine to normal operating temperature.
Stop the engine.
Remove the spark plug (page 3-5).
Install the compression gauge [1] into the spark plug
hole.
Turn the ignition switch ON and engine stop switch  .
Shift the transmission into neutral.
Open the throttle all the way and crank the engine with
the starter motor until the  gauge reading stops rising.
Low compression can be caused by:
– Blown cylinder head gasket
– Improper valve adjustment
– Valve leakage
– Worn piston ring or cylinder
High compression can be caused by:
– Carbon deposits in combustion chamber or on piston head
CYLINDER HEAD COVER
REMOVAL
Remove the following:
– Spark plug cap (page 3-5)
– PAIR check valve (page 7-18)
– Fuel tank (page 7-8)
– Ignition coil (page 5-6)
Remove the three bolts [1] and ground terminal [2] from
the radiator reserve tank stay.
Remove the cylinder head cover bolts [1], rubber seals
[2], cylinder head cover [3] and packing [4].
To avoid
discharging the
battery, do not
operate the starter
motor for more than
7 seconds.
STANDARD:1,294 kPa at 490 min-1 (rpm) (13.2 kgf/cm2, 188 psi)
[1]
[1]/[2]
[1]
[1]/[2]
[3]/[4] 
						

							10-5
dummyhead
dummyhead
CYLINDER HEAD/VALVES
INSTALLATION
Apply sealant (Three bond 5211C, 1207B, 1215, SS
KE45 or equivalent) to the cylinder head semi-circular
cut-outs as shown.
Install a new packing [1] into the cylinder head cover [2]
groove.
Install the cylinder head cover onto the cylinder head.
Check the rubber seals [1] are in good condition,
replace them if necessary.
Install the rubber seals to the cylinder head cover with
their UP marks [2] facing up.
Install and tighten the cylinder head cover bolts [1] to
the specified torque.
[2][1]
[2]
[1]
TORQUE: 10 N·m (1.0 kgf·m, 7 lbf·ft)
[1] 
						

							10-6
dummyhead
dummyhead
CYLINDER HEAD/VALVES
Set the radiator reserve tank stay and ground terminal
[1] in position.
Install and tighten the three bolts [2].
Install the following:
– Ignition coil (page 5-6)
– PAIR check valve (page 7-18)
– Fuel tank (page 7-8)
– Spark plug cap (page 3-5)
CAMSHAFT
REMOVAL
Remove the cylinder head cover (page 10-4).
Make sure the piston is at TDC (Top Dead Center) on
the compression stroke (page 3-6).
Remove the cam chain tensioner lifter plug [1] and O-
ring [2].
Turn the cam chain tensioner lifter shaft fully in
(clockwise) and secure it using a tensioner stopper [1]
to prevent damaging the cam chain.
Be careful not to letthe cam chain
guide bolts fall into the crankcase.Remove the bolts [1] and cam chain guide B [2].
[1]/[2]
[2]
[2]
[1]
TOOL:
Tensioner stopper 070MG-0010100
[1]
[1]
[2] 
						

							10-7
dummyhead
dummyhead
CYLINDER HEAD/VALVES
Be careful not to let
the camshaft holder
bolts fall into the crankcase.Remove the bolts [1] and camshaft holders [2].
From outside to inside, loosen the bolts in a crisscross
pattern in several steps or the camshaft holder might
break.
Attach a piece ofwire to the cam
chain to prevent it
from falling into the
crankcase.Remove the camshafts [1] by removing the cam chain
[2] from the cam sprockets.
Lift the rocker arms [1].
Remove the shims [2].
 • Do not allow the shims to fall into the crankcase.
 • Mark all shims to ensure correct reassembly in theiroriginal locations.
 • The shims can be easily removed with a tweezers or
a magnet.
INSPECTION
Inspect the following parts for damage, abnormal wear,
deformation, burning or clogs in oil passages.
– Cam sprocket
– Camshaft
– Camshaft holder/dowel pin
– Cam chain guide B
Measure each part according to CYLINDER HEAD/
VALVES SPECIFICATIONS (page 1-6).
Replace any part if it is out of service limit.
[2]
[1]
[1]
[2]
[1]
[1][2] 
						

							10-8
dummyhead
dummyhead
CYLINDER HEAD/VALVES
CAMSHAFT OIL CLEARANCE
Do not rotate thecamshaft when
using plastigauge.Wipe any oil from the journals of the camshaft, cylinder
head and camshaft holders.
Lay a strip of plastigauge [1] lengthwise on top of each
camshaft journal.
Be sure the dowel
pins in the camshaft
holder align the
holes in the cylinder head.Install each camshaft holder to the correct locations
with the identification marks [1].
– R mark: right camshaft holder
– L mark: left camshaft holder– IN mark: intake side
– EX mark: exhaust side
Apply engine oil to the camshaft holder mounting bolt
[1] threads and seating surface.
Failure to tighten the camshaft holder in a crisscross
pattern may cause a camshaft holder to break.
Tighten all camshaft holder mounting bolts to the
specified torque.
From inside to outside, tighten the bolts in a crisscross
pattern in several steps.
Remove the camshaft holders and measure the width
of each plastigauge.
The widest thickness determines the oil clearance.
When the service limit is exceeded, measure the
camshaft journal O.D. and camshaft journal area I.D. of
cylinder head and camshaft  holders, then compare the
measurement with the standard value (page 1-6).
 • Replace the cylinder head and camshaft holders as a set if the difference from the standard value is
larger than that of the camshaft. 
 • Replace the camshaft if the difference from the standard value is larger than that of the cylinder
head and camshaft holders. 
[1]
[1]
TORQUE: 12 N·m (1.2 kgf·m, 9 lbf·ft)
[1]
SERVICE LIMIT: 0.10 mm (0.004 in) 
						

							10-9
dummyhead
dummyhead
CYLINDER HEAD/VALVES
INSTALLATION
Be careful not to
jam the cam chain
and timing sprocket on the crankshaft
when rotating the crankshaft.Rotate the crankshaft counterclockwise, and align the
T mark [1] on the flywheel with the index notch [2] on
the left crankcase cover.
Be careful not to letthe shims fall into the crankcase.Install the shims [1] in their original locations on the
valve retainer.
Lower the rocker arms [2].
Each camshaft has an identification mark.
 • IN mark [1]: intake camshaft
 • EX mark [2]: exhaust camshaft
Apply molybdenum oil solution to the camshaft [1] lobes
and journal surfaces.
Apply engine oil to the cam chain [2] whole surface.
Install the camshafts into the cylinder head while
installing cam chain ont o the cam sprockets.
Install the camshaft with its lobes facing up.
[1]
[2]
[2]
[2][1]
[1]
[2]
[1]
[2] 
						

							10-10
dummyhead
dummyhead
CYLINDER HEAD/VALVES
Align the outside index line (IN [1] and EX [2] marks)
on the cam sprockets with the cylinder head top surface
as shown.
 • Check that the punch marks [3] of the cam sprockets
is facing up as shown.
Install the camshaft holders.
Note the correct locations  with the identification marks
[1] as shown.
– R mark: right camshaft holder
– L mark: left camshaft holder – IN mark: intake side
– EX mark: exhaust side
Apply engine oil to the camshaft holder mounting bolt
[1] threads and seating surface.
Install and tighten the camshaft holder mounting bolts
to the specified torque.
From inside to outside, tighten the bolts in a crisscross
pattern in several steps.
Be careful not to let the cam chain
guide bolts fall into the crankcase.Install the cam chain guide B [1] and bolts [2].
Tighten the cam chain guide bolts securely.
[1][2][3]
[1]
TORQUE: 12 N·m (1.2 kgf·m, 9 lbf·ft)
[1]
[2]
[1] 
						

							10-11
dummyhead
dummyhead
CYLINDER HEAD/VALVES
Remove the tensioner stopper [1] from the cam chain
tensioner lifter.
Apply engine oil to a new O-ring [1] and install it to the
cam chain tensioner lifter.
Install and tighten the cam chain tensioner lifter plug [2]
to the specified torque.
Inspect the valve clearance (page 3-6).
Install the cylinder head cover (page 10-5).
ROCKER ARM
 • The rocker arm can be serviced with the engineinstalled in the frame.
 • The intake and exhaust rocker arm service procedures are the same.
REMOVAL/INSTALLATION
Remove the camshafts (page 10-6).
Remove the bolt [1] and sealing washer [2].
[1]
TORQUE: 4.2 N·m (0.4 kgf·m, 3.1 lbf·ft)
[1]
[2]
[1]/[2] 
						

							10-12
dummyhead
dummyhead
CYLINDER HEAD/VALVES
Remove the rocker arm shaft [1] using a 6 mm bolt [2]
while holding the rocker arm [3].
Remove the rocker arm.
Apply molybdenum oil solution to the rocker arm inner
surface, roller surface, slipper surface and rocker arm
shaft outer surface.
Install the rocker arm  and rocker arm shaft.
 • The rocker arms are identified by the stamped
marks:
– IN: Intake rocker arm [4]
– EX: Exhaust rocker arm [5]
Install a new sealing washer [1] and bolt [2].
Install the camshafts (page 10-9).
INSPECTION
Inspect the following parts for damage, abnormal wear,
deformation, burning or clogs in oil passages.
– Rocker arm
– Rocker arm shaft
Measure each part and clearance according to
CYLINDER HEAD/VALVES SPECIFICATIONS (page
1-6).
Replace any part if it is out of service limit.
[3][1][2]
[5][4]
[1]
[2] 
						

							10-13
dummyhead
dummyhead
CYLINDER HEAD/VALVES
CYLINDER HEAD
REMOVAL
Remove the following:
– Engine (page 15-4)
– Camshaft (page 10-6)
Remove the cylinder head bolts [1], nuts [2], washers
[3] and cylinder head [4].
 • Attach a piece of wire to the cam chain to prevent itfrom falling into the crankcase.
 • Do not tap the cylinder head too hard and do not
damage the mating surface with a screwdriver.
Remove the following:
– Dowel pins [1]
– Gasket [2]
– Cam chain guide A [3]
DISASSEMBLY
Remove the following:
– Spark plug (page 3-5)
–O
2 sensor (page 4-47)
– Rocker arm (page 10-11)
Remove the valve spring cotters [1] using the special
tools.
Remove the following:
– Spring retainer
– Outer/inner valve springs
–Valve
– Stem seal
– Spring seat
INSPECTION
Inspect the following parts for damage, abnormal wear,
deformation, burning or clogs in oil passages.
– Cylinder head
– Inner/outer valve springs
– Valves
– Valve guides
– Cam chain guide A
Measure each part and clearance according to
CYLINDER HEAD/VALVES SPECIFICATIONS (page
1-6).
Replace any part if it is out of service limit.
Be careful not to let
the cylinder head
bolts and nuts fall
into the crankcase.
[1]
[2]/[3]
[4]
[1]
[2][3]
To prevent loss of
tension, do not
compress the valve
springs more than necessary to
remove the cotters.
TOOLS:
[2] Valve spring compressor 07757-0010000
[3] Valve spring compressor
attachment 07959-KM30101
Mark all parts during disassembly so
they can be
installed in their
original locations.
[2]
[1][3]