SHERCO 250 SEF RACING Instruction manual

WORKSHOPMANUAL | MANUELD’ATELIER | MANUALDETALLER
250 SEF RACING
250 SEF FACTORY
300 SEF RACING
300 SEF FACTORY

1
Table of contents
FORWARD .......................................................... 2
TOOL LIST .......................................................... 3
TECHNICAL SPECIFICATION............................. 4
ENGINE .............................................................. 4
FRAME ............................................................... 5
STANDARD ADJUSTMENT ................................ 6
FORK ................................................................. 6
SHOCK ABSORBER ............................................ 7
OPERATIONS REQUIRING DEMOUNTING OR NOT
ENGINE .............................................................. 8
REMOVING / REISTALLING THE ENGINE ...... 9
REMOVING THE ENGINE ................................ 9
REINSTALLING THE ENGINE ......................... 9
ENGINE .......................................................... 1
REMOVING THE CYLINDER HEAD ...................... 10
❱❘ Preparation ........................................................... 10
❱❘ Removing the cam chain tensioner ................... 10
❱❘
Removing the camshafts ..................................... 11
❱❘ Removing head cylinder ..................................... 11
INDIVIDUAL PARTS INSPECTION ................ 12
ENGINE TOP END CONTROLS ..................... 12
❱❘ Inspection of the cylinder for wear .................... 12
❱❘ Piston wear ........................................................... 13
❱❘ Cylinder head inspection .................................... 15
❱❘ Visually inspect the timing chain for damage .. 15
❱❘ Valve – Guide clearance ..................................... 15
REASSEMBLING THE TOP END OF THE ENGINE 16
❱❘ Reassemble the piston ....................................... 16
❱❘ Reassemble the cylinder head ........................... 17
❱❘ Valve timing .......................................................... 18
❱❘ Valve clearance .................................................... 20
❱❘ Replacing the timing chain ................................. 20
DISASSEMBLING COVER ............................. 21
DISASSEMBLING THE RIGHT SIDE ............. 21
❱❘ Clutch dismantling .............................................. 21
❱❘ Inspection of the clutch ...................................... 21
❱❘ Check the clutch spring length .......................... 21
❱❘ Disassembling and inspecting the water pump22
❱❘ Removing the clutch hub and the clutch basket23
❱❘ Reassembling the clutch hub components ...... 23
DISASSEMBLING THE LEFT SIDE ................... 24
❱❘ Disassembling the ignition case ........................ 24
❱❘ Replacing the stator and sensor system .......... 24
❱❘ Removing the rotor ............................................. 25
❱❘ Inspect the freewheel and the needle bearings 25
❱❘ Reassembling the ignition case ......................... 26
DISASSEMBLING CRANKCASES ................. 27
CRANKSHAFT - TRANSMISSION - CENTRAL
CRANKCASES ............................................... 27
❱❘ Disassembling the transmission and the crankshaft 27
❱❘ Checking
the transmission components
28
❱❘ Checking the crankshaft ..................................... 29
❱❘ Checking the crankcase ..................................... 30
❱❘ Reassembling the central crankcase assembly30
TIGHTENING TORQUES .................................34
INJECTOR BODY ............................................36
C ean injector body ........................................36
❱❘ Material ................................................................. 36
❱❘ Put down the injector body ................................ 36
❱❘
Clean of injector body ......................................... 38
❱❘ Replace the injector body................................... 38
ELECTRICAL INSTALLATION CHECKING ....39
❱❘ 1- Fan control ....................................................... 39
❱❘ 2-CDI ..................................................................... 39
❱❘ 3-Fuel pump control ............................................ 39
❱❘ 4-Fall sensor control ........................................... 40
❱❘ 5-Checking the voltage regulator ...................... 40
❱❘ 6-Battery control .................................................. 40
❱❘ 7-Map sensor control .......................................... 41
❱❘ 8-TPS sensor control .......................................... 41
❱❘ 9-Stepper motor control ..................................... 42
❱❘ 1 -Injector control ............................................... 42
❱❘ 11-Starter control ................................................ 42
❱❘ 12-Checking the alternator ................................. 43
❱❘ 13-Hall sensor control (Crankshaft) .................. 43
❱❘ 14-Water sensor control ..................................... 44
15-Ignition coil control ........................................... 44
WIRING HARNESS .........................................45
❱❘ Homologated light wire harness (8145) ............. 45
❱❘ Racing light wire harness (6845) ......................... 46
❱❘ Main wire harness (7314) .................................... 47
❱❘ Fan wire harness (3577) ......................................... 48
SYNERJECT
)
INJECTION SYSTEM INSTRUCTION
MANUAL ...........................................................49
SYNERJECT
)
INJECTION SYSTEM P R E S E N T A T I O N49
1.1- Injection system .............................................. 49
1.2- Description Exxodiag diagnostic Tools référence
4967 .......................................................................... 50
1.3- Diagnostic tool kit contents. .......................... 50
1.4- Installation of the diagnostic tool .................. 51
2.1- Connection with Keyless system ................... 55
2.2- Software settings : configuration menu ................... 57
2.3- Update menu and synchronization ................ 58
2.4- Using the sofware ............................................... 60
C- Reading the default codes ......... 62
D- Erasing default codes................. 63
E- Test the actuators ....................... 65
F- Updating the computer ...................................... 67
G- Screen printing function ................................... 69

FORWARD
This manual is designed rimarily for skilled mechanics working in a ro erly equi ed worksho . The
execution of the o erations in this manual requires a strong mechanical knowledge and s ecific
SHERCO tools designed for the 250 SEF and 300 SEF engine.
This worksho manual is a su lement to the SHERCO 250 SEF and 300 SEF owner’s manual.
.

3
25 /3 SEF
TOOL LIST
TOOL 25 /3 4T
Fuel ressure
tool 8691
Clutch tool 1814
Su ort iston tool
1818
Ring extractor R464 Pinion clutch
shaft tool 1817
Tool ignition
4753
Flying
extractor R462
To dead oint
1819
Diagnostic
Injection tool 8561
Tools 0726
Container / Su ort
Engine Tool R481/R455
SUSPENSION
Inner tube
clam 7670
To ca
wrench 7666
Oil seal
insert 7668
Seal Hammer
7669
Piston rod
holder 7667
7671
FACTORY
RACING
Tool fit u
5028
Clam Jaw
5031
Tool fit sealing
5029
Tool x lor ca
7189
Owner manual
8700

4
TECHNICAL SPECIFICATION
ENGINE
25 SEF 3 SEF
Ty e Liquid cooled single cylinder 4 strokes engine
Dis lacement 249.4 CC 303.7 CC
Bore / Stroke 78/52,2mm 84 / 54.8mm
Com ression ratio 13 :1 12.4:1
Fuel Without lead 95 or 98
Valve timing 4 valves, DOHC driven by tooth ty e chain
Admission valve diameter 31mm 31mm
Exhaust admission valve 26mm
Thickness admission valve 0.15-0.2mm
Thickness exhaust valve 0.2-0.25mm
Crankshat bearing 2 roller bearing
Piston Aluminium forge
Lubrification Lubrication under ressure with 2 trochoidal um s
Motor oil 1 liter SAE 5w40
Primary reduction ratio 21 :70
GEAR BOX :
1st
2nd
3nd
4nd
5nd
6nd
6 s eed
14 : 33
17 : 30
19 : 28
21 : 26
23 : 24
25 :
22
Final transmission 13 X 49 13 X 48
Clutch Multi-disk in oil bath. Hydraulic command
Ignition system / Battery Electric 12V 4Ah / LTZ5S Lithium 12V 2Ah
Electronic injection Synerject

5
25 /3 SEF
TECHNICAL SPECIFICATION
FRAME
Frame
Semi
-
erimeter CrMo steel with aluminum subframe
Fork KAYABA USD Ø48mm Closed cartridge(FACTORY)
WP XPLOR USD Ø48mm (RACING)
Rear sus ension
KAYABA sus ension with se arate cylinder
WP sus ension with se arate cylinder
,
Aluminium swing arm
Travel Front/Rear FACTORY 330/330mm
RACING 300/330mm
Front brake disque Ø 260mm
Rear brake disque Ø 220mm
Brake disc limit : 2.7mm front et 3.6mm rear
Front tire 90/90-21’’
Rear tyre 140/80-18’’
Pressure front / Rear 0.9 bar
Fuel tank ca acity 9.7l with1 liter of reserve
Angle of the steering column
27.3°
Wheel base 1480mm
Weight (without fuel) 102 kg

6
STANDARD ADJUSTMENT
FORK
Original settings – Fork KAYABA USD Ø48 mm
Com ression Comfort 20 clicks back
Standard 12 clicks back
S ort 8 clicks back
Rebound Comfort 18 clicks back
Standard 12 clicks back
S ort 10 clicks back
S ring Rider weight : 65-75 kg 4.0N/mm
Rider weight : 75-85 kg 4.2N/m
Rider weight : 85-95 4.4N/m
Fork oil 01M 345 CC
Original settings – Fork WP XPLOR sus ension USD Ø48mm
Com ression Comfort 18 clicks back
Standard 15 clicks back
S ort 12 clicks back
Rebound Comfort 18 clicks back
Standard 15 clicks back
S ort 12 clicks back
Preload Comfort +0 tours
Standard +0 tours
S ort +6 tours
S ring stiffness Rider weight : 65 - 75 kg 4.2N/mm
Rider weight : 75 - 85 kg 4.4N/mm (original)
Rider weight : 85 - 95 kg 4.6N/mm
Ty e of oil SAE 4
S ring length with reload s acer 474 mm
Quantity of oil 606ml
Oil level measurement (fork com ressed and s ring
removed) from the to of the fork tube
100mm (min30-max 120 mm)

7
25 /3 SEF
STANDARD ADJUSTMENT
SHOCK ABSORBER
Racing Settings – KAYABA shock absorber
Low-s eed com ression Comfort 20 clicks back
Standard 14 clicks back
S ort 12 clicks back
High-s eed com ression Comfort 2,5 turns back
Standard 1.5 turns back
S ort 1 turn back
Rebound Comfort 15 clicks back
Standard 13 clicks back
S ort 11 clicks back
S ring stiffness Rider weight : 65-75 kg 46N/mm
Rider weight : 75-85 kg 48N/mm (original)
Rider weight : 85-95 kg 50N/mm
Ty e of oil K2C
Racing Settings – WP sus ension shock absorber
Low-s eed com ression Comfort 17 clicks back
Standard 12 clicks back
S ort 9 clicks back
High-s eed com ression Comfort 2 turns back
Standard 1.5 turns back
S ort 1 turn back
Rebound Comfort 16 clicks back
Standard 14 clicks back
S ort 12 clicks back
S ring stiffness Rider weight : 65-75 kg 51N/mm
Rider weight : 75-85 kg 54N/mm (original)
Rider weight : 85-95 kg 57N/mm

8
OPERATIONS REQUIRING DEMOUNTING OR NOT ENGINE
REMOVING ENGINE NOT DEMOUNTING ENGINE
Crankshaft •
Gear box •
Crankshaft bearing •
Gear Box bearing •
Piston •
Cylinder •
Cylinder head •
Valve timing •
Ignition •
Pinion of ignition system •
Freewheel •
Clutch •
Water um •
Oil um •
Gear selection •

9
25 /3 SEF
REMOVING / REISTALLING THE ENGINE
REMOVING THE ENGINE
• Drain (refer to the owner’s manual)
- the engine oil
- the engine coolant
• Remove the seat.
• Disconnect the battery.
• Remove the fuel tank and its covers.
• Disconnect all the electrical wiring connectors from the engine.
(Starter, TPS sensor, water tem erature sensor, coil, fuel injector)
• Remove the exhaust.
• Remove the ignition coil.
• Remove the fuel injector body.
• Remove the chain.
• Remove the chain guard.
• Remove the clutch actuating cylinder.
• Remove all of the water hoses connected to the motor.
• Remove the left radiator.
• Loosen all of the engine bolts [A].
• Loosen the swing arm bolt.
• Remove the brackets that attach the cylinder head to the chassis.
• Remove the motor mounting bolts.
• Remove the swing arm bolt.
• Remove the motor.
REINSTALLING THE ENGINE
The motor should be reinstalled in the frame in the reverse order of how it was removed. The following
torque values should be utilized.
Tightening torques:
Motor mounting bolts: 6 Nm
Swing arm axle nut: 1 Nm
Clutch receiver screws: 1 Nm
Cylinder head bracket bolts: 23Nm
Exhaust mounting bolts:
WARNING
To remove the engine, you must remove the swing arm axle, the swing arm and the
rear wheel.
To keep the bike from falling, remember to support the chassis with an appropriate jack.
WARNING
When the clutch actuating cylinder is removed the piston is loose. Hold the piston it in place
using a plastic strap.

10
ENGINE
For additional details refer to the arts catalog 250 SEF _ 300 SEF
REMOVING THE CYLINDER HEAD
• Remove the s ark lug.
• Remove the valve cover.
• Remove the three valve cover screws.
❱❘ Preparation
• Place the engine on the R455 engine su ort tool.
• Drain the engine oil (see user manual).
•
Make sure to be in a clean environment before
starting the dismantling of the engine.
• Remove the ignition cover lug [A]
•
Remove the timing control lug [A]
• Turn the engine counterclockwise in order to
align the timing marks on the crankshaft with
the marks on the timing gear. Install the
s ecial tool that locks the engine at To Dead
Center
❱❘ Removing the cam chain tensioner
• Remove the screws from the cam
chain tensioner as shown in the hoto.
• Remove the cam chain tensioner.
• Remove the s ark lug well
WARNING
These three screws are equipped with o rings. Ref: 0900

11
25 /3 SEF
ENGINE
❱❘
Removing the camshafts
• Unscrew the eight screws from the shaft
bearing ca cam following the order shown
in the icture.
• Remove the bearing ca .
• Remove the exhaust camshaft retaining cli .
• Remove the exhaust camshaft.
• Remove the intake camshaft retaining cli .
• Remove the intake camshaft.
❱❘ Removing head cylinder
• Remove the two nuts M6 and the washer.
• Remove the cylinder head bolts (Be
sure to loosen them in the correct direction).
• Remove the cylinder head.
• Remove the head gasket and the cylinder
WARNING
Black bolt N°1 on the picture is longer, 3 bolts are identical.

12
INDIVIDUAL PARTS INSPECTION
ENGINE TOP END CONTROLS
❱❘ Inspection of the cylinder for wear
Measure the inside diameter of the cylinder
when it is cold.
Ins ect the inside of the cylinder for any scratches
or other evidence of abnormal wear. If the cylinder
is badly damaged or worn it should be re laced.
Since the cylinder does not wear in a uniform
manner measure in from side to side and u and
down as shown.
If the inside measurement of the cylinder exceeds
the tolerance limit it must be re laced.
.
(A)=1 mm
(B)=25 mm
Standard 25 SEF
Cylinder diameter (A):77.982±0.008mm
Cylinder diameter (B):77.982±0.015mm
Taper limit: 0.05mm
Out of round limit:0.05mm
Standard 3 SEF
Cylinder diameter (A):83.982±0.01mm
Cylinder diameter (B):83.982±83.995mm
Taper limit:0.05mm
Out of round limit:0.05mm
Piston / Cylinder clearance
To determine the iston / cylinder clearance as
accurately as ossible it is sufficient to measure
the iston and the cylinder, and then calculate the
difference between the two values. Measure the
diameters as shown.
Piston / Cylinder clearances
Standard 0.03 – 0.05 mm
Limit 0.10 mm

13
25 /3 SEF
INDIVIDUAL PARTS INSPECTION
❱❘ Piston wear
• Using a micrometer measure the outside
diameter of the iston [A] 10mm [B] above the
bottom of the iston and at right angles to the axis
of the iston.
If the outer diameter of the iston is below the
tolerance it must be re laced.
Piston 25 SEF= 77.9400±0.005 mm
Piston 3 SEF= 83.950±0.005 mm
Ring groove / Piston ring
• Using a feeler gauge measure the clearance
between the iston ring and the ring groove.
• Check in several laces to determine the
actual clearance if the clearance is greater
than the maximum, re lace the iston ring and
if necessary the iston.
Ring groove / piston ring Standard
Compression ring: 0.030-0.065 mm
Limit: 0.13 mm
Oil ring: 0.020-0.055 mm
Limit: 0.13 mm
Ring end ga
• Compression ring: 0.3-0.4 Limit 0.7 mm
• Oil ring: 0.3-0.5 mm
Ins ect the connecting rod, the iston
in and the iston for wear
• Visually ins ect the circli s in lace.
If they a ear worn or distorted re lace them. If
the hole for the circli s a ears worn re lace the
iston.
• Measure the iston in with a micrometer. If at
any lace on the in the diameter is below the
limit re lace the iston in.
Measure the diameter of the iston in holes in
the iston and the hole in the connecting rod. If
the one or more holes in the iston are
incorrect re lace the iston. If the diameter of
the hole in the connecting rod is incorrect,
re lace the connecting rod

14
INDIVIDUAL PARTS INSPECTION
Check the camshafts for wear
• Remove the camshafts.
• Measure the heights [A] of the camshaft lobes
with a micrometer.
If the cams are worn beyond the limits,
re lace the cams.
Camshaft height limit 25
Exhaust: 32.10 mm
Intake: 32.40 mm
Camshaft height limit 3
Exhaust: 32,10 mm
Intake: 32.40 mm
Checking the camshafts and camshaft
journals for wear
• Measure the clearance between the camshaft
and the camshaft journals using lastigage
[A].
• Lubricate the fixing bolts with engine oil and
tighten to the ro er torque.
Tightening torque
Camshaft journal mounting bolts: 1 Nm
If any of the measurements are over the limit,
then measure the diameter of each journal.
Camshaft / journal clearance Standard:
. 2 – . 62 mm
Limit: .15 mm
If the diameter of the journal is below the limit
re lace the camshaft and measure again.
Camshaft journal diameter Standard:
23. 5 – 23.25 mm
Limit 23. 2 mm
If the clearance is outside of the tolerance limits,
re lace the entire cylinder head
Eccentricity of the camshaft
• Measure the camshasft runout.
If it is out of tolerance, re lace the camshaft.
Runout : Less than . 3

15
25 /3 SEF
INDIVIDUAL PARTS INSPECTION
❱❘ Cylinder head inspection
Ins ect the cylinder head for flatness
• Place the cylinder head on the workbench.
• Using a recision straight edge [A] and a
feeler gauge check the head for war age;
check in several laces as shown in the
hoto.
If the war age is above the limit, re air if
ossible. If the damage is severe re lace the
head.
Cylinder head warpage:
Limit = . 5 mm
❱❘ Visually inspect the timing
chain for damage
• Clean all arts.
• Visually ins ect the drive chain : check for any
hard s ot, resistance, or wear. If any, it must be
changed.
• Visually ins ect the distribution drive inion.
Change if necessary.
• Visually ins ect distributions guide lates :
change them if necessary.
• Visually ins ect the inion (1) ; re lace if
necessary.
• Check that the needle bearings fit tight when
the inion (1) is mounted on its axis.
❱❘ Valve – Guide clearance
Intake :
Mini clearance : 0.02 mm
Maxi clearance : 0.045 mm
Escape :
Mini clearance : 0.04 mm
Maxi clearance : 0.065 mm

16
REASSEMBLING THE TOP END OF THE ENGINE
❱❘ Reassemble the piston
• Install the iston rings on the iston with the
end ga s as shown in the hoto, the
com ression ring goes in the to groove and
the oil control ring goes in the bottom groove.
A Lower ex ander end ga
B Lower iston ring end ga
C U er ex ander end ga
D U er iston ring ga
• A ly engine oil to the wrist in internal bore
in the iston.
• Carefully note the iston orientation. (the small
cut outs are on the exhaust side)
Use s ecial tool number 1821 to maintain the
iston in the correct location 1 .
• Place one of the cli s in the s ecial tool
number 2075 as shown in the hoto; install
the cli close to one end of the tool
• Use the tool to set u the cli for installation
on the wrist in.
• Install the circli on the wrist in
WARNING
The expander rings do not have a top or bottom;
however the oil control ring and the compression
ring must be installed with the « N » mark facing up.
WARNING
Use the same head gasket. (Thickness 0.3 or
0.4mm depending on the model)

17
25 /3 SEF
REASSEMBLING THE TOP END OF THE ENGINE
• Install the wrist in into the iston and
connecting rod using the tool and lightly
ta ing with a hammer.
• Install the o osite circli , using the s ecial
tool.
• Install the cylinder over the iston using an
a ro riate ring com ressor
• Install the two cylinder head locating ins
[A].
• Install the head gasket [B].
• Install the cylinder head.
❱❘ Reassemble the cylinder head
• Install the head bolts noting the different
lengths; tighten them using two asses in the
order shown in the hoto.
• Install and tighten the two M6 nuts.
Cylinder head torque:
Studs
1
st
pass: 3 Nm
2
nd
pass: 45 Nm
Nuts M6: 1 Nm
WARNING
The two internal bolts are of different length
and are equipped with washers.

18
REASSEMBLING THE TOP END OF THE ENGINE
❱❘ Valve timing
• Beware if the tool number 1819 is still
ro erly installed.
• Install the intake cam.
• Install the exhaust cam.
(see the icture for how to set the timing marks)
• Install the camshaft retaining cli s.
• A ly moly disulfide grease to the
camshafts

19
25 /3 SEF
REASSEMBLING THE TOP END OF THE ENGINE
• Install the camshaft retaining cover. ( ay
careful attention to the tightening order).
Camshaft retaining cover torque 1 Nm
• Install the camshaft chain tensioner using a
new gasket.
Torque the two fixing bolts to: 1 Nm
• Install the cam tensioner adjusting bolt ( ay
attention to the o-ring).
Torque the tensioner adjusting screw to: 1 Nm
• Remove the s ecial tool number 1819.
• Rotate the engine a few times to make sure
that the valve timing is correct.
• Finally check the valve timing using the timing
marks.
• Re lace the ca that was removed to install
tool number 1819.
Torque the cap to: 8Nm
• Re lace the s ark lug well.
• A ly a thin coat of silicone to the
camshaft end ca bores.
• Re lace the valve cover.
• Install the valve cover installation bolts.
Torque the bolts to: 8Nm
WARNING
Make sure that the o rings are installed
on the spark plug well.
WARNING
The screw n°1 is a M6 X 35