2004 YAMAHA YZ250LC check oil

4-30
CYLINDER HEAD, CYLINDER AND PISTONENG
EC475383
Cylinder head and cylinder
1. Apply:
9Engine oil
To piston 1piston ring 2and cylinder sur-
face.
2. Install:
9Cylinder 1
cC
Make sure the piston rings are properly
positioned. Install the cylinder with one
hand while compressing the piston rings
with the other hand.
NOTE:
After installing, check the smooth movement of
the piston.
3. Install:
9Nut (cylinder) 1
NOTE:
Tighten the nuts in stage, using a crisscross pat-
tern.
3. Install:
9Piston 1
9Piston pin 2
9Piston pin clip 3
NOTE:
9The arrow aon the piston dome must point to
exhaust side.
9Before installing the piston pin clip, cover the
crankcase with a clean rag to prevent the pis-
ton pin clip from falling into the crankcase cavi-
ty.
cC
Do not allow the clip open ends to meet the
piston pin slot b b
.
42 Nm (4.2 m•kg, 30 ft•lb)
5XF-9-30-4B 4/22/03 8:59 AM Page 6

4-69
CRANKCASE AND CRANKSHAFTENG
EC4N5284
Crankshaft
1. Install:
9Crankshaft 1
Use the crankshaft installing tool 2, 3, 4.
EC4N5102
Oil seal
1. Install:
9Oil seal (left) 1
9Oil seal (right) 2
NOTE:
9Apply the lithium soap base grease on the oil
seal lip.
9Install the oil seal with its manufacture’s marks
or numbers facing outward.
Crankshaft installing tool:
Pot 2:
YU-90050/90890-01274
Bolt 3:YU-90050/90890-01275
Adapter 4:YU-90063/90890-01278
2. Check:
9Shifter operation
9Transmission operation
Unsmooth operation
Repair.
å åB
åFor USA and CDN
∫Except for USA and CDN
NOTE:
9Hold the connecting rod at top dead center with
one hand while turning the nut of the installing
tool with the other. Operate the installing tool
until the crankshaft bottoms against the bear-
ing.
9Before installing the crankshaft, clean the con-
tacting surface of crankcase.
9Apply the lithium soap base grease on the oil
seal lip.
cC
Do not use a hammer to drive in the crank-
shaft.
5XF-9-30-4C 5/8/03 11:50 AM Page 40

4-71
CRANKCASE AND CRANKSHAFTENG
8. Tighten:
9Segment 1
9Bolt (segment) 2
NOTE:
9When installing the segment onto the shift cam
3, align the punch mark awith the dowel pin
b.
9Turn the segment clockwise until it stops and
tighten the bolt.
30 Nm (3.0 m•kg, 22 ft•lb)
7. Install:
9Tension spring 1
9Holder 2
9Bolt (holder) 3
NOTE:
Install the holder so that it contacts the projec-
tion aon the crankcase (right).
10 Nm (1.0 m•kg, 7.2 ft•lb)
9. Remove:
9Sealant
Forced out on the cylinder mating surface.
10. Apply:
9Engine oil
To the crank pin, bearing, oil delivery hole
and connecting rod big end washer.
11. Check:
9Crankshaft and transmission operation
Unsmooth operation
Repair.
14 Nm (1.4 m•kg, 10 ft•lb)
6. Install:
9Bolt (crankcase) 1
NOTE:
Tighten the crankcase tightening bolts in stage,
using a crisscross pattern.
5XF-9-30-4C 5/8/03 11:50 AM Page 44

4-74
TRANSMISSION, SHIFT CAM AND SHIFT FORKENG
EC4H5000
ASSEMBLY AND INSTALLATION
EC4H5242
Transmission
1. Install:
95th pinion gear (21T) 1
93rd pinion gear (18T) 2
9Collar 3
94th pinion gear (22T) 4
92nd pinion gear (15T) 5
To main axle 6.
NOTE:
9Apply the molybdenum disulfide oil on the 4th
and 5th pinion gears inner circumference and
on the end surface.
9Apply the molybdenum disulfide oil on the 2nd
and 3rd pinion gears inner circumference.
3. Check:
9Shift fork movement
Unsmooth operation
Replace shift fork.
NOTE:
For a malfunctioning shift fork, replace not only
the shift fork itself but the two gears each adja-
cent to the shift fork.
2. Inspect:
9Shift cam 1
9Segment 2
Wear/Damage
Replace.
EC4H4810
Shift fork, shift cam and segment
1. Inspect:
9Shift fork 1
Wear/Damage/Scratches
Replace.
5XF-9-30-4C 5/8/03 11:50 AM Page 50

4-76
TRANSMISSION, SHIFT CAM AND SHIFT FORKENG
5. Install:
9Shift fork 1 (L) 1
9Shift fork 2 (C10) 2
9Shift fork 3 (R) 3
9Shift cam 4
To main axle and drive axle.
NOTE:
9Apply the molybdenum disulfide oil on the shift
fork grooves.
9Mesh the shift fork #1 (L) with the 4th wheel
gear 5and #3 (R) with the 5th wheel gear 7
on the drive axle.
9Mesh the shift fork #2 (C10) with the 3rd pinion
gear 6on the main axle.
6. Install:
9Transmission assembly 1
To crankcase (left) 2.
NOTE:
Apply the transmission oil on the bearings and
guide bars.
7. Check:
9Shifter operation
9Transmission operation
Unsmooth operation
Repair.
5XF-9-30-4C 5/8/03 11:50 AM Page 54

5-34
CHASFRONT FORK
13. Check:
9Inner tube smooth movement
Tightness/Binding/Rough spots Repeat the
steps 2 to 12.
14. Compress the front fork fully.
15. Fill:
9Front fork oil
Until outer tube top surface with recom-
mended fork oil 1.
cC
9Be sure to use recommended fork oil. If
other oils are used, they may have an ex-
cessively adverse effect on the front fork
performance.
9Never allow foreign materials to enter the
front fork.
16. After filling, pump the damper rod 1slowly
up and down more than 10 times to distrib-
ute the fork oil.
17. Fill:
9Front fork oil
Until outer tube top surface with recom-
mended fork oil once more.
18. After filling, pump the outer tube 1slowly
up and down (about 200 mm (7.9 in) stroke)
to distribute the fork oil once more.
NOTE:
Be careful not to excessive full stroke. A stroke
of 200 mm (7.9 in) or more will cause air to en-
ter. In this case, repeat the steps 15 to 18.
Recommended oil:
Suspension oil “01”
5XF-9-30-5B 5/10/03 8:54 AM Page 18

5-35
CHASFRONT FORK
19. Wait ten minutes until the air bubbles have
been removed from the front fork, and the
oil has dispense evenly in system before
setting recommended oil level.
NOTE:
Fill with the fork oil up to the top end of the outer
tube, or the fork oil will not spread over to every
part of the front forks, thus making it impossible
to obtain the correct level.
Be sure to fill with the fork oil up to the top of the
outer tube and bleed the front forks.
20. Measure:
9Oil level (left and right) a
Out of specification  Adjust.
NOTE:
Be sure to install the spring guide 2when
checking the oil level.
w
Never fail to make the oil level adjustment
between the maximum and minimum level
and always adjust each front fork to the
same setting. Uneven adjustment can
cause poor handling and loss of stability.
Standard oil level:
123 mm (4.84 in)
*125 mm (4.92 in)
Extent of adjustment:
105~135 mm (4.13~5.31 in)
From top of outer tube with
inner tube and damper rod
1 1
fully compressed without spring.
*For EUROPE
5XF-9-30-5B 5/10/03 8:54 AM Page 20

6-2
IGNITION SYSTEMELEC
EC620000
IGNITION SYSTEM
EC621003
INSPECTION STEPS
Use the following steps for checking the possibility of the malfunctioning engine being attributable to
ignition system failure and for checking the spark plug which will not spark.
*Clean or replace
spark plug.
Primary coil
Secondary coil
Repair or replace.
Spark
Check entire ignition
system for connection.
Spark gap test
No good
No good
No good
No good
No good
No good No Spark
Check “ENGINE STOP”
button.
Pick-up coil
Source coil
Check ignition coil.
Check CDI magneto.
Replace CDI unit.
Replace.
Replace.
Replace.
Replace.
Replace.
*marked: Only when the ignition checker is used.
NOTE:
9Remove the following parts before inspection.
1) Seat
2) Fuel tank
9Use the following special tools in this inspection.
Dynamic spark tester:
YM-34487
Ignition checker:
90890-06754Pocket tester:
YU-3112-C/90890-03112
OK
OK
OK
OKReplace.
Check spark plug cap.No good
OK
5XF-9-30-6 4/21/03 2:13 PM Page 4