SHERCO 250 SE-R Instruction manual

MANUEL D’ATELIER I WORKSHOP MANUAL I MANUAL DE TALLER
250 SE-R
300 SE-R

2
SUMMARY
FOREWORD ............................................................................................................................................................................. 4
This manual is intended primarily for use by trained mechanics in a properly equipped workshop. The various operations require
strong mechanical skills and specific tools to work on the SHERCO 250 SE-R and SE-R 300 engines. This workshop manual
complements the SHERCO 250 SE-R and SE-R 300 manual........................................................................................................ 4
ENGINE SPECIFICATIONS............................................................................................................................................................. 6
CHASSIS SPECIFICATIONS........................................................................................................................................................... 7
FRONT FORK – FACTORY SETTINGS............................................................................................................................................ 8
REAR SHOCK – FACTORY SETTINGS............................................................................................................................................ 9
OPERATIONS PERFORMED WITH THE ENGINE IN AND OUT OF THE FRAME................................................................................. 10
REMOVING/INSTALLING THE ENGINE ......................................................................................................................................... 11
Removing the engine........................................................................................................................................... 11
DISASSEMBLY OF THE ENGINE.................................................................................................................................................. 13
Draining the transmission oil .............................................................................................................................. 13
Removing the sprocket and the gear selector ...................................................................................................... 13
Removing the cylinder head, cylinder and piston.................................................................................................. 14
Removing the clutch............................................................................................................................................ 15
Removing the pressure plate and discs................................................................................................................ 15
Removing the electric starter............................................................................................................................... 16
Removing the primary drive gear......................................................................................................................... 16
Removing the interlock mechanism ..................................................................................................................... 17
Removing the ignition cover................................................................................................................................. 18
Removing the electric starter double gear and the starter drive............................................................................ 18
Removing the flywheel ........................................................................................................................................ 19
Intake manifold and reeds ................................................................................................................................... 19
Separating the housing halves............................................................................................................................. 20
Removing the transmission components.............................................................................................................. 20
Removing the crankshaft..................................................................................................................................... 21
ENGINE COMPONENTS.............................................................................................................................................................. 22
Crankshaft........................................................................................................................................................... 22
Checking the crankshaft dimensions ................................................................................................................... 22
Radial clearance of the big end:........................................................................................................................... 22
Lateral play of the connecting rod:....................................................................................................................... 23
Checking the runout of the crankshaft: ................................................................................................................ 23
Piston.................................................................................................................................................................. 23
250-300 SE-R

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SUMMARY
End gap............................................................................................................................................................... 23
Checking the cylinder for wear ............................................................................................................................ 24
Remanufactured cylinder..................................................................................................................................... 24
Disassembly of the exhaust valve system ............................................................................................................ 25
Checking the operation of the exhaust valve and the boosters ............................................................................. 29
Reed valves, intake manifold ............................................................................................................................... 31
Clutch.................................................................................................................................................................. 31
REASSEMBLING THE ENGINE .................................................................................................................................................... 32
Crankshaft........................................................................................................................................................... 32
Gearbox............................................................................................................................................................... 32
Assembling the crankcase halves........................................................................................................................ 33
Selector mechanism............................................................................................................................................ 34
Clutch and primary drive ..................................................................................................................................... 34
Clutch discs, pressure plate................................................................................................................................. 36
Clutch housing .................................................................................................................................................... 36
Piston and cylinder .............................................................................................................................................. 37
Cylinder head ...................................................................................................................................................... 37
Reed valves and intake manifold ......................................................................................................................... 38
Transmission output sprocket .............................................................................................................................. 38
Mounting the starter drive ................................................................................................................................... 38
Installing the flywheel and the ignition cover........................................................................................................ 39
Installing the electric starter ................................................................................................................................ 39
TIGHTENING TORQUE TABLE ..................................................................................................................................................... 40
CHECKING THE CHARGING SYSTEM .......................................................................................................................................... 42
Static control values (engine off) 250 SE-R/300 SE-R .......................................................................................... 42
Dynamic control values:....................................................................................................................................... 42
WIRING DIAGRAMS ................................................................................................................................................................... 43
Main harness 4511.............................................................................................................................................. 43
CDI Harness 4512................................................................................................................................................ 45
Lighting Harness 250 SE -R/300 SE-R ................................................................................................................. 47
Lighting Harness - Racing 250 SE -R/300 SE-R ................................................................................................... 48
Wiring Harness – accessories.............................................................................................................................. 49

4
Foreword
250-300 SE-R
This manual is intended primarily for use by trained mechanics in a properly equipped workshop.
The various operations require strong mechanical skills and specific tools to work on the SHERCO
250 SE-R and SE-R 300 engines.
This workshop manual complements the SHERCO 250 SE-R and SE-R 300 manual.

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Engine tool list for use
❱❘ on the 250 SE-R and 300 SE-R
Tool Reference Description
R447 Clutch block
5207 Flywheel block
2067 Swingarm tool
R467 Tool for the oscillating input shaft bearing housing
R465 Secondary shaft bearing tool
5397 Gearbox bearing output shaft tool
R446 Gearbox output shaft tool
5398 Roller bearing selection tool
5399 Left crankcase bearing tool
R469 Right crankcase bearing tool
5400 Clutch side crankshaft bearing tool
5401 Ignition side crankshaft bearing tool
5402 HK0808 needle bearing tool
(water pump , starter motor double pinion, starter motor bearing)
1968 Water pump seal tool
1821 Motor support
5206 Primary pinion block tool
2073 Spring block (selection fingers)
5208 Flywheel puller
R464 Crankshaft ring extractor
R453 Selector shaft bearing assembly tool
R444 Oil seal installation tool

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 EngineSpecications
250-300 SE-R
❱❘ Engine
Type Single cylinder, 2-stroke, liquid cooled
Displacement 249,32 CC 293,14 CC
Bore/Stroke 66,4/72 mm 72/72 mm
Fuel Unleaded gasoline with an octane rating of at least 95 with
a (2%) mix of 2-stroke oil
Cooling Liquid with forced circulation
Ignition system DC-CDI system with digital advance
Spark plug NGK BR8ES / DENSO W24ESRU
Spark plug gap 0.7 mm
Piston Forged aluminum
Engine oil 900 ml of SAE 10W40
Transmission primary drive ratio 27 : 75
Transmission:
1st
2nd
3rd
4th
5th
6th
6 speed
14 : 32
15 : 26
19 : 27
21 : 24
23 : 22
25 : 21
Transmission final drive 14 X 49
Clutch Hydraulically operated, multi disc in oil bath
Starter Electric starter
Battery 12V 4Ah
Alternator 220W
Carburetor Keihin PWK 36
Setting carburetor 250
Main jet : 165
Idle jet : 40
Needle : N8RJ
Position : N° 4 begin to the top
Air screw : 1T 1/2
Throttle : N°7
300
Main jet: 165
Idle jet : 38
Needle : N8RG
Position : N° 3 begin to the top
Air screw : 1T 1/2
Throttle : N°7

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 ChassisSpecications
❱❘ Chassis
Frame Semi-perimeter Cr-Mo steel with an aluminum subframe
Fork SACHS 48mmØ USD Series (standard) & WP 48mmØ USD series
(racing)
Rear Suspension WP shock with remote cylinder and aluminum control rods
Travel Front/Rear 300/330mm
Front brake disc 270mm Ø (standard), 256mm Ø (racing)
Rear brake disc 220mm Ø
Disc brake wear limit 2.7mm front and 3.6mm rear
Front tire 90/90-21’’
Rear tire 140/80-18’’
Tire air pressure (all terrain) 0.9 bar (13 psi)
Fuel tank capacity 9.5L with 1 liter of reserve (2.5 gallons/.25 gallons)
Steering angle in both directions 27.3°
Wheelbase 1470mm (57.9 inches)
Weight 110 kg (242.5 pounds)

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factory settings
250-300 SE-R
❱❘ Front fork
Front fork factory settings – SACHS 48mmØ USD Series
Compression 12 clicks back
Rebound 12 clicks back
Spring stiffness 4.5N/mm
Fork oil SAE 5
Quantity of oil per leg 600cm3(20.3 fluid ounces)
Oil level (with the fork compressed, and the spring removed.
Measured from the top of the fork tube)
130mm (5.12 inches)
Front fork factory settings – WP 48mm Ø USD Series
Compression Comfort 20 clicks back
Standard 13 clicks back
Sport 8 clicks back
Rebound Comfort 18 clicks back
Standard 13 clicks back
Sport 10 clicks back
Preload Comfort 4 turns
Standard 6 turns
Sport 8 turns
Spring stiffness Rider weight: 65-75 kg (143 – 165 pounds) 4.0N/mm
Rider weight: 75-85 kg (165 -187 pounds) 4.2N/mm (original)
Rider weight: 85-95 kg (187 – 210 pounds) 4.4N/mm
Fork oil SAE 4
Oil level (with the fork compressed,
and the spring removed. Measured
from the top of the fork tube)
110mm (4.33 inches)

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factory settings
❱❘ Rear shock
Factory settings – WP rear suspension unit
Low speed Compression Comfort 20 clicks back
Standard 15 clicks back
Sport 12 clicks back
High speed Compression Comfort 2.5 turns back
Standard 2 turns back
Sport 1.5 turns back
Rebound damping Comfort 15 clicks back
Standard 13 clicks back
Sport 11 clicks back
Spring stiffness Rider weight: 65-75 kg (143 – 165 pounds) 48N/mm
Rider weight: 75-85 kg (165 – 187 pounds) 51N/mm (original)
Rider weight: 85-95 kg (187 – 210 pounds) 54N/mm

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Operations performed with the engine in and out of the frame
Operations requiring engine
removal
Operations that do not require
engine removal
Crankshaft (including connecting rod)
Transmission - Complete •
Crankshaft bearings •
Transmission bearings •
Piston •
Cylinder •
Cylinder head •
Ignition •
Starting motor gearing •
Complete clutch •
Water pump •
Transmission gear selector mechanism •
250-300 SE-R

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❱❘ Removing the engine
CAUTION
In order to remove the engine, the swing arm pivot bolt must be removed. This allows the swing arm and the rear wheel
assembly to be separated from the bike. To insure that the bike does not fall, support it with a jack .
- Drain (See the owners manual)
 •Theengineoil
 •Theenginecoolant
- Remove the seat.
- Disconnect the battery.
- Remove the fuel tank with its valves.
- Disconnect all of the wiring harnesses that are connected to the engine (starter, etc.).
- Remove the exhaust (See the owner’s manual).
- Remove the carburetor.
- Remove the chain (use the master link).
- Remove the chain guard.
- Remove the clutch slave cylinder.
CAUTION
When the clutch slave cylinder is removed the piston is no longer contained. Retain the piston with a plastic tie.
- Remove the water lines connected to the engine.
- Remove the left radiator.
- Loosen all of the engine mounting bolts.
- Loosen the swing arm axle bolt.
- Remove the mounting brackets that are attached to the cylinder head and the electric motor.
- Remove the rear axle.
- Remove the swing arm axle.
- Disconnect all of the cables from the valve block.
- Remove the motor.
Removing/installing the engine

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Removing/installing the engine
250-300 SE-R
❱❘ Reinstalling the engine
- The installation of the engine back into the frame
should follow in reverse order the way it was
removed. Note the torque value of all of the moun-
ting bolts.
CAUTION
Be careful when installing the engine. The cable ten-
sion of the exhaust valve control mechanism is very
critical to the proper operation of the engine. Follow
these steps in order to properly adjust the cables.
- When replacing the cables make sure that the
cable [1] is completely relaxed in respect to the
mounting nut.
- Tighten the cable until the pulley reaches the stop,
it will rotate in a counterclockwise direction.
- When this position is reached, do not tighten the
cable any further.
- Tighten the lock nut.
Tightening torques:
Engine mounting bolts: 60 Nm (44 lb-ft)
Swingarm nut: 100 Nm (74 lb-ft)
Clutch slave cylinder bolts: 10 Nm (7.4 lb-ft)
Cylinder head bracket bolts: 23 Nm (17 lb-ft)
1
Position poulie câble détendu

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Disassembly of the engine
❱❘ Removing the sprocket and the gear
selector
- Straighten the security tab [3] using a suitable
punch.
- Remove the nut and the sprocket [4].
- Remove the bolt [5] and the gear selector.
- Remove the clutch control rod.
Refer to the exploded view in the parts catalog for the 250 SE-R / 300 SE-R
❱❘ Draining the transmission oil
- Remove the drain plugs [1] and [2], let the oil
drain.
2
1
3
4
5

14
Disassembly of the engine
250-300 SE-R
❱❘ Removing the cylinder head, cylinder
and piston
- Remove the cylinder head mounting bolts [1] the
cylinder head and the two o-rings.
- Remove the four socket head bolts [3] and the
four washers [2] located on the base of the cylin-
der.
- Remove the cylinder.
- Remove the piston pin retaining clips.
- Remove the piston pin.
- Remove the piston and the needle bearing from
the connecting rod.
- Remove the base gasket.
1
3
2

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Disassembly of the engine
❱❘ Removing the pressure plate and discs
- Carefully loosen all of the screws [1] on the pressure plate.
- Remove the screws, the springs and the spring cups.
❱❘ Removing the clutch
- Déposer les vis et le couvercle de pompe à eau.
Retirer le joint de forme.
- Remove the clutch cover screws and the cover.
Remove the seal.
1

16
Disassembly of the engine
250-300 SE-R
- Remove the pressure plate and the discs.
- Remove the clutch release bearing assembly [1]
located in the primary shaft.
❱❘ Removing the electric starter
- Remove the 2 screws [2].
❱❘ Removing the primary drive gear
- Secure the end of the crankshaft gear with the
special tool 5206 [3].
- Loosen the fixing nut [4] and remove the nut,
primary drive gear and the conical washer.
- Open the safety washer on the clutch hub nut [5].
- Use special tool R447 [6] to hold the clutch hub
and loosen the nut.
- Remove the tool.
- Remove the nut, the clutch hub and the two nee-
dle bearings.
1
2
2
4
3
6
5

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Disassembly of the engine
- Remove the primary gear and spacer [1] from the
crankshaft.
CAUTION Note the pin and the seal. The primary drive
gear and the clutch hub are matched so they can not
be changed separately. They must be replaced as a set.
❱❘ Removing the interlock mechanism
- Use a screwdriver to compress the spring on the
ratchet mechanism so that it no longer engages the
shifting drum. Remove the selector shaft.
CAUTION Make sure that the washer stays at the
bottom of the housing.
- Remove the retaining bolt [2] and then remove the
[3] shifting interlock mechanism.
CAUTION Note the location of the dowel pin that
locates the interlock mechanism. The locking lever must
be removed if the case is changed.
- Remove the bolt [4] and then remove the lever
along with the spring and the spacer.
1
2
3

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Disassembly of the engine
250-300 SE-R
❱❘ Removing the ignition cover
- Remove the retaining screws, and then remove
the ignition cover along with the gasket.
❱❘ Removing the electric starter double
gear and the starter drive
- Remove the three shoulder bolts [1].
- Remove the double gear retaining bracket [2].
- Remove the double gear [3] and the needle bea-
ring.
- Remove the starter drive [4].
1
2
3
4

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Disassembly of the engine
❱❘ Removingtheywheel
- Hold the flywheel with special tool #5207 [1] and
remove the retaining nut [2].
- Use the extracting tool 5208 [3] and remove the
flywheel [4].
❱❘ Intake manifold and reeds
- Remove the four bolts [5].
- Remove the intake manifold, the reed block and
the associated parts.
2
1
5
4
3

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Disassembly of the engine
250-300 SE-R
❱❘ Separating the housing halves
- Turn the engine so that the ignition side is facing
you.
- Remove all of the screws.
- Remove the sealing ring from the output shaft
along with the o-ring.
- Lift the engine by the left crankcase half and use
a small plastic mallet to tap on the gearbox output
shaft in order to separate the two halves.
CAUTION
Do not use a screwdriver or any other tool to attempt
to separate the halves. Damage to the mating surfaces
can occur.
- Separate the halves at the center joint.
CAUTION
Pay careful attention to the shims that are on the end
of the transmission shafts as they can stay attached to
the housings.
❱❘ Removing the transmission
components
- Remove the transmission lubrication tube [1].
- Remove the main shaft shim [2].
- Remove the shifting fork shafts and push the
shifting forks aside in order to release the shifting
drum.
- Remove the shifting drum.
- Remove the shifting forks.
CAUTION
When removing the shifting forks pay attention to the
rollers [4] that are located on the forks. Identify them
so that they can be reinstalled in the same location
when the transmission is reassembled.
3
3
1
2
4