APRILIA YP 250 4T User manual

QUICK WORKSHOP
HANDBOOK
YP 250 4T Motor

aprilia
YP 250 4T
Release 02 / 2000 - 05
General safety norms 1
2
3
44
5
6
7
8
Technical data
Oil chart
Special engine tools
Carburettor
Engine timing
Adjusting valve play
Produced by
Training and Documentation Department
Aprilia Consumer Service s.p.a.
via Noalese, 156 - 30036 Santa Maria di Sale (Venice) - Italy
Tel. **39 - 041 57 86 101
Fax **39 - 041 57 86 100
www.serviceaprilia.com
www.aprilia.com
Produced and printed by
Studio Gallo (Engineering)
Vicolo Perazzolo,5
35012 Camposampiero (PD)
tel. **39 - 049 - 5794676
fax.**39 - 049 - 5794676
Italy
www.stgallo.it
e-mail: [email protected]
INTRODUCTIONGENERAL INDEX
- This manual contains all the essential information
for carrying out routine vehicle procedures.
- The information and diagrams in the manual are
up-to-date at the time of publication.
- This publication is intended for use by Aprilia
dealers and their trained mechanics. A large
number of procedures do not require explanation
and therefore have been omitted. It has not been
possibletogivedetailedmechanicaldataforevery
procedure. All personnel consulting this manual
must therefore possess the basis skills of a
mechanicandbethoroughly familiar with the most
common motor cycle repair procedures. Without
theseskillsandthenecessaryfamiliarityanyrepair
orroutinemaintenanceINTRODUCTIONoperation
may be ineffective or even dangerous.
- Given the fact that it is not possible to provide
detaileddescriptionsofallprocedures,special care
mustbe taken for whatever repairor maintenance
work is done, in order to prevent damage to the
vehicle and injury to persons.
- In order to provide the best level of customer
satisfaction, Aprilia s.p.a. constantly improves its
productsand relevant documentation.Allimportant
technical changes and alterations to procedures
are notified to all Aprilia dealers, branches and
points of sale throughout the world. All changes
will be included in later editions of this manual.
- If you have any doubts or queries about the
procedures described in this manual, please
contact the Aprilia Consumer Service (A.C.S.)
Department, who will be pleased to give you all
the information and explanations you require, and
to bring you up to date with any changes.
For further information see:
- SPARE PARTS CATALOGUE no. 655X
Without alteration to the basic features of its models
as described and illustrated in this manual, Aprilia
s.p.a. maycarryoutmodificationstoanyofthemodels
without notice.
Unauthorizedelectronic retrieval or reproductionofany
partofthismanualisunlawfulinallcountries.Products
or services manufactured or provided by third parties
are quoted merely as examples and do not constitute
a recommendation; Aprilia s.p.a. is not liable for the
performance or use of such products and services.
Second edition. May 2000.
01 / 01Chap.1
Disassembly/Reassembly
sequence
Technical observations

aprilia
YP 250 4T
Release 02 / 2000 - 05
GENERAL SAFETY STANDARDS
CARBON MONOXIDE
If the engine must be switched on to carry out certain
operations make sure the room is well ventilated or open to
the outside. Never switch on the engine in a closed room,
unless there is a smoke and fume removal system installed
and the operating.
Exhaust fumes contain carbon monoxide, a poisonous
gas which make cause loss of consciousness and can
be lethal.
Switch on the engine only in an open space or in a closed
room if fitted with a fully operating smoke and fume removal
system.
FUEL
Make sure the room is well ventilated. Extinguish all
cigarettes, keep fuel containers away from flames and
possible sources of sparks.
Fuel is highly flammable and may explode.
KEEP OUT OF THE REACH OF CHILDREN
HIGH TEMPERATURE COMPONENTS
The engine and parts of the exhaust system reach very
high temperatures and remain hot for a certain period
after switching off the engine. Handle these components
only after putting on protective gloves or waiting for the
engine and parts to fully cool down.
USED ENGINE OIL
Use latex gloves for maintenance operations involving
contactwith oil. Ifleft in contact with theskin for longperiods,
used engine oil can cause skin cancer. Although this is
unlikely, unless handled every day, wash your hands with
soap and water after handling used engine oil.
KEEP OUT OFTHE REACH OF CHILDREN
DANGER
DANGER
DANGER
DANGER
GENERAL PRECAUTIONS AND INFORMATION
For repair and disassembly and reassembly operations
follow this instructions.
Do not carry out any operation in the presence of
naked flames.
Before starting any maintenance or inspection
operation, switch off the engine and remove the
ignition key. Wait for the engine and exhaust system
to cool down. Place the motor cycle, if possible, in a
raised position on a level, even surface. Take special
care of heated parts (engine and the exhaust) in order
to avoid burns.
The vehicle is made with parts which cannot be
swallowed. Do not bite, chew, suck or otherwise
attempt to carry out operations using the teeth or
mouth.
Unless otherwise specified, to reassemble parts,
reverse the order for disassembly operations. Some
operations may involve disassembling parts
previously disassembled for other operations to be
carried out. Consult the various pages of the manual
where each operation is described in order to avoid
unnecessary work. Never use fuel as a solvent for
cleaning the vehicle.
Ifwelding operationsare tobe carriedout, disconnect
the negative pole (-) of the battery. If more than one
person is working on the vehicle make sure both are
in a safe position whatever the work being done.
BEFORE DISASSEMBLY
- Before separating pipes or wires etc. (joints and
junctions) mark each part with a unique marking.
Each piece should be clearly marked for reassembly
purposes.
-Clean and wash the disassembled components with
close to non-inflammable detergent.
-Keep paired parts together, because normal wear and
tear create a natural pairing. In some cases, where one
part is replaced the other must also be replaced.
Keep away from sources of heat.
DISASSEMBLY
-Before separating pipes or wires etc. (joints and
junctions) mark each part with a unique marking.
Each piece should be clearly marked for reassembly
purposes.
-Clean and wash the disassembled components with
close to non-inflammable detergent.
-Keep paired parts together, because normal wear and
tear create a natural pairing. In some cases, where one
part is replaced the other must also be replaced.
Keep away from sources of heat.
DANGER
01 / 02
Chap.1

aprilia
YP 250 4T
Release 02 / 2000 - 05
REASSEMBLY
Never re-use an elastic ring. If removed, replace it
with a new ring. If a new ring is fitted, do not stretch
more than necessary when fitting it to the shaft.
Afterwards, check that the ring is properly fitted to
the housing.
Do not clean bearings with compressed air.
IMPORTANT Bearings must rotate freely, without
sticking or noise. Replace if necessary.
-Use only ORIGINAL Aprilia SPARE PARTS.
-Sticktotheoilchartandrecommendedwearingparts.
-Wherever possible, lubricate parts before
reassembling them.
-When tightening screws and nuts begin with the
largestdiameters, or innernutsandscrews, andtighten
diagonally.Tighteneach before finally tightening to the
specified torque.
-Always replace gaskets, seal rings, elastic rings, O
rings and split pins with new ones.
-Clean all joint surfaces, oil guard edges and gaskets
before reassembling.
-Lightly smear the edges of oil guards with lithium
based grease.
-Refit the oil guards and bearings with the trademark
ormanufacturer’sserial numberfacing outwards (so it
is visible).
-Grease the bearings fully before fitting.
-Check that all components have been reassembled
properly.
After a maintenance or repair operation, carry out
preliminary checks and commission the vehicle on
private property or in a low traffic area.
WARNING
Chap.1
REFRIGERATION LIQUID
Refrigeration liquid is dangerous if swallowed;
contact with the skin or eyes could cause irritation.
For contact of this kind, wash with plenty of water
and see a doctor immediately.
If swallowed, it causes vomiting: rinse the mouth
and throat with plenty of water and see a doctor
immediately.
01 / 03
THIS LIQUID AND CONTAINER SHOULD BE
PROPERLY DISPOSED OF.
KEEP OUT OF THE REACH OF CHILDREN.
Be careful not to pour any refrigeration liquid onto
hot engine parts; it could catch fire. The flames
are invisible.
Wear latex gloves during maintenance operations.
Donot use the motor cycle ifthe refrigeration liquid
is below the minimum required level.
Refrigeration liquid consists of one part water (50%)
for one part anti-freeze (50%) .
Thismixture issuitablefor mostoperatingtemperatures
and also guarantees good rust protection.
The use of the same blend is recommended during
the summer, because this reduces evaporation and
the need for frequent top ups.
It also reduces mineral salt deposits in the radiator left
byevaporatedliquid and maintains the cooling system.
If the outside temperature is below 0° C, check the
refrigeration circuit frequently, adding anti-freeze if
required (for greater concentration). Max 60% anti-
freeze.
Use distilled water in the refrigerating liquid, in order
not to damage the engine.
Refrigeration liquid for the engine (recommended):
ECOBLU - 40°C or COOL
On the basis of the freezing point of the refrigeration
liquid required, add water in the percentage given
below:
IMPORTANT: Features vary from anti-freeze to anti-
freeze. Consult the label for the degree of protection
provided.
Use only nitrite free anti-freeze and anti-corrosion
liquid, guaranteeing protection to at least -35°C.
-20°
-30°
-40°
35°
45°
55°
Freezing point
°C Refrigeration liquid % by volume
WARNING
DANGER

aprilia
YP 250 4T
Release 02 / 2000 - 05
TECHNICAL INFORMATION
Engine type
Cylinders
Engine size
Bore
Compression ratio
Pressure (STD)
Ignition
Lubrication
4-stroke, water-cooled, overhead camshaft
Single cylinder, tilted forwards
0,249l (249 cc)
69,0 x 66,8 mm
10 :1
1400 kPa (14 Kg/cc, 14 bar) at 500 rpm
electric starter motor
oil sump
Engine oil
(STANDAR APISE or higher grade)
Routine oil change
Total capacity
Total capacity transmission oil
Air filter : carburettor side
Cover side
1,2L
1,4L
0,25L
moist filter element
dry filter element
ENGINE
OIL TYPE AND GRADE
02 / 01Chap.2
CARBURETTOR
Type/Quantity
Manufacturer
Type
Manufacturer
Distance between electrodes
Y28V - 1A/1
TEIKEI
DR 8 EA
NGK
0,6 ~ 0,7 mm
SPARK PLUG
Primary reduction
Reduction ratio
Secondary reduction
Rapporto di riduzione secondaria
Type of transmission
Functioning
Automatic single speed
TRANSMISSION
Clutch type
ELECTRIC PLANT
Ignition
Generator
CLUTCH
helical gears
40/15 (2,666)
cylindrical gears
38/15 (2,533)
Automatic single speed (trapezoidal belt)
automatic centrifuge
2,34 ~ 0,82 : 1
dry automatic centrifuge
T.C.I. (digital)
Magnet A.C.

aprilia
YP 250 4T
Release 02 / 2000 - 05
TIGHTENING TORQUES
Component to tighten
Oil control bolt
Exhaust stud bolt
Spark plug
Cam pinion cap
Cylinder head and cylinder
Cylinder head and cylinder
(Cam chain side)
Valve cap
Rotor
Valve adjustment lock nut
Camshaft bearing plug
Cam pinion
Distribution chain stretcher
(Casing)
(Plug)
Guide plug 2
Water pump housing cap
Coupling joint
Thermostat valve cap
Fuel filler support
Oil pump
Oil pump cap
Discharge plug
Carburettor joint
Carburettor joint and carburettor
Air filter unit
Air filter cap
Fuel pump
Exhaust pipe
Muffler
Muffler ands exhaust pipe
Guard (muffler)
Guard (exhaust pipe)
Half-cover (left and right)
Exhaust bolt
Oil filler inlet
Transmission cover
Cover cap (left)
Filter cover cap
Cover cap guard
Magnet cap
Cap (oil pump)
Ignition control plug
Single direction clutch
Clutch housing
Grease (primary pulley)
Fixed primary plug
Clutch unit
Stator
Collection coil
Starter motor
Heating switch
Heating unit
Thread
size
M6
M8
M12
M6
M8
M6
M6
M16
M6
M6
M10
M6
M8
M6
M6
M6
M6
M5
M6
M3
M35
M6
M6
M6
M5
M6
M8
M10
M8
M6
M6
M6
M8
M14
M8
M6
M6
M6
M6
M6
M16
M8
M14
M4
M14
M36
M5
M5
M6
M16
P/t 1/8
Q.ty
1
2
1
2
4
2
5
1
2
2
1
2
1
1
3
2
2
1
2
1
1
2
2
2
5
2
2
3
1
3
2
9
1
1
6
11
3
2
10
2
1
3
1
4
1
1
3
2
2
2
1
7
13
18
10
22
10
10
80
14
8
60
10
8
10
10
7
10
5
7
1
32
10
10
7
1
10
20
53
20
10
10
10
22
3
16
10
7
7
10
12
8
30
60
3
60
90
7
7
10
23
8
Torque
0,7
1,3
1,8
1,0
2,2
1,0
1,0
8,0
1,4
0,8
6,0
1,0
0,8
1,0
1,0
0,7
1,0
0,5
0,7
0,1
3,2
1,0
1,0
0,7
0,1
1,0
2,0
5,3
2,0
1,0
1,0
1,0
2,2
0,3
1,6
1,0
0,7
0,7
1,0
1,2
0,8
3,0
6,0
0,3
6,0
9,0
0,7
0,7
1,0
2,3
0,8
Nm Kgm
Name of part
-
-
-
Bolt
Nut
Bolt
Bolt
Nut
Nut
Bolt
Bolt
Bolt
Bolt
Bolt
Bolt
-
Bolt
Bolt
Screw
Bolt
Bolt
Bolt
Nut
Bolt
Screw
-
Nut
Bolt
Bolt
Screw
Screw
Bolt
Bolt
Bolt
Bolt
Bolt
-
Bolt
-
Bolt
Cap
-
Bolt
-
-
-
-
-
Bolt
-
-
02 / 02Chap.2

aprilia
YP 250 4T
Release 02 / 2000 - 05
Component
Cylinder head:
Deformation limit
Cylinder:
Bore
Out-of-oval limit
Camshaft:
Cam dimensions
Aspiration A
B
C
Discharge A
B
C
Off-center limit
Distribution chain:
Type/Number of meshes
Rocker arm/rocker arm shaft:
Rocker arm inner diameter
Rocker arm shaft outer diameter
Shaft/rocker arm play
Valves, valve housings, valve guides:
Valve play (cold) ASP
SCAR
Valve dimensions
Head diameter A ASP
SCAR
Face width B ASP
SCAR
Housing width C ASP
SCAR
Margin thickness D ASP
SCAR
Outer stud bolt diameter ASP
SCAR
Inner guide diameter ASP
SCAR
Rating
***
69,000-69,005 mm
***
36,545 ~ 36,645 mm
30,021 ~ 30,121 mm
6,524 mm
36,547 ~ 36,647 mm
30,067 ~ 30,167 mm
6,48
***
DID SC A-0404A SDH/104
12,000 ~ 12,018 mm
11,981 ~ 11,991 mm
0,009 ~ 0,012 mm
0,08 ~ 0,12 mm
0,16 ~ 0,20 mm
33,9 ~ 34,1 mm
28,4 ~ 28,6 mm
3,394 ~ 3,960 mm
3,394 ~ 3,960 mm
0,9 ~ 1,1 mm
0,9 ~ 1,1 mm
0,8 ~ 1,2 mm
0,8 ~ 1,2 mm
5,975 ~ 5,990 mm
5,960 ~ 5,975 mm
6,000 ~ 6,012 mm
6,000 ~ 6,012 mm
Limit
0,03 mm
69,1 mm
0,03 mm
36,45 mm
29,92 mm
***
36,45 mm
29,97 mm
***
0,03 mm
***
12,03 mm
11,995 mm
***
***
***
***
***
***
***
***
***
***
***
5,94 mm
5,92 mm
6,05 mm
6,05 mm
"A"
"B" "C"
"D"
02 / 03Chap.2

aprilia
YP 250 4T
Release 02 / 2000 - 05
Component
Play between stud bolt and guide ASP
SCAR
Guide off-center limit
Valve housing width ASP
SCAR
Valve spring:
Free length (inner) ASP/SCAR
(Outer) ASP/SCAR
Dimensions when fitted (valve closed)
(Inner) ASP/SCAR
(Outer) ASP/SCAR
Negative pressure
(Inner) ASP/SCAR
(Outer) ASP/SCAR
Limite inclinazione (Inner) ASP/SCAR
(Outer) ASP/SCAR
Piston:
Play between piston and cylinder
Piston diameter D
Measurement H
Piston pin housing bore
Piston pin outer diameter
Piston segments:
Upper segment:
Type
Distance to edge (fitted)
Side play (fitted)
2nd segment:
Type
Distance to edge (fitted)
Side play (fitted)
Scraper ring:
Distance to edge (fitted)
Engine shaft:
Crank width A
Off-axis limit C
Connecting rod side play D
Rating
0,010 ~ 0,037 mm
0,025 ~ 0,052 mm
***
0,9 ~ 1,1 mm
0,9 ~ 1,1 mm
38,1 mm
36,93 mm
30,1 mm
31,6 mm
7,8 ~ 9,0 kg
37,22 ~ 42,83 kg
***
***
0,02 ~ 0,04 mm
68,965 ~ 68,980 mm
5 mm
17,004 ~ 17,015 mm
16,991 ~ 17,000 mm
Rectangular
0,15 ~ 0,30 mm
0,04 ~ 0,08 mm
Tapered
0,30 ~ 0,45 mm
0,30 ~ 0,07 mm
0,2 ~ 0,7 mm
59,95 - 60,0 mm
0,03 mm
0,35 - 0,85 mm
Limit
0,08 mm
0,1 mm
0,01 mm
1,6 mm
1,6 mm
36,1 mm
35,0 mm
***
***
***
***
2,5°/1,7 mm
2,5°/1,7 mm
0,15 mm
***
***
17,045 mm
16,975 mm
***
0,45 mm
0,12 mm
***
0,7 mm
0,12 mm
***
***
***
***
02 / 04Chap.2

aprilia
YP 250 4T
Release 02 / 2000 - 05
1
1 Examination:
·Driving gear (oil pump)
·Driven gear (oil pump) (1)
·Oil pump housing
·Oil pump float cap
·For wear/cracking/damage: replace
2 Measurement
·Play between rotors [A]
· (between inner rotor (1) and outer rotor (2)
·Side play [B]
· (between outer rotor (2) and the pump
housing (3).
Out of spec: replace the oil pump
·Play between housing and rotor [C]
(between the pump housing (3) and
rotors (1) (2)
Out of spec: replace the oil pump.
OIL PUMP
CONTROL OF OIL PUMP
02 / 05Chap.2
Play between rotors [A]
0,10 ~ 0,34 mm
<Limit: 0,40 mm>
Side play [B]
0,013 ~ 0,036 mm
<Limit: 0,15 mm>
Play between housing and rotor
[C]
0,04 ~ 0,09 mm
<Limit: 0,15 mm>
1
2
A
3BC

aprilia
YP 250 4T
Release 02 / 2000 - 05
Component
Clutch and automatic centrifuge:
Clutch block thickness
Clutch bell inner diameter
Brake spring fre length
Weight outer diameter
Clutch - mesh rpm
Clutch - block rpm
Trapezoidal belt:
Belt width
Carburettor:
Type
Serial number
Venturi pipe outer diameter
Main jet (M.J.)
Main air jet (M.A.J.)
Cone-shaped pin (J.N.)
Butterfly valve dimension (Th.V.)
Minimum air jet (P.A.J.1)
Atomization (N.J.)
Minimum output (P.O.)
Minimum jet (P.J.)
Bypass (B.P.)
Idling screw (P.S.)
Valve housing measurement (V.S.)
Starter jet 1 (G.S.1)
Starter jet 2 (G.S.2)
Float height (F.H.)
Idling rpm
Aspiration negative pressure
Oil temperature
Cooling liquid temperature
Oil pump:
Type
End play
Side play
Play between housing and rotor
Rating
3,0 mm
135 mm
28,1 mm
20 mm
2.100 ~ 2.700 rpm
3.700 ~ 4.700 rpm
22,6 mm
Y28V-1A
4UC 03[4UD 00 (CH)]
Ø28
#130
Ø0.9
5D32-3/5
11°
Ø1,2
#85
Ø0,8
#44
0,7 x 4
1 7/8
1,4
Ø 0,45
Ø 0,5
27 mm
1.350 - 1.450 rpm
220-260 mmHg
65-75° C
80°C
Trochoid
0,1-0,34 mm
0,013 - 0,036 mm
0,04 - 0,09 mm
Limit
2,0 mm
135,5 mm
***
19,5 mm
***
***
21,0 mm
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
0,4 mm
0,15 mm
0,15 mm
02 / 06Chap.2

aprilia
YP 250 4T
Release 02 / 2000 - 05
Component
Bearings and oil guard:
Connecting rod bearing
Engine shaft bearing (left)
Engine shaft bearing (right)
Engine shaft oil guard (left)
Engine shaft oil guard (right)
Water pump bearing
Water pump seal ring
Primary shaft bearing (left)
Primary shaft bearing (right)
Secondary shaft bearing (left)
Secondary shaft bearing (right)
Secondary shaft oil guard
Camshaft bearing (left)
Camshaft bearing (right)
Primary transmission bearing (left)
Primary transmission bearing (right)
Primary transmission oil guard
Dimension
32 x 40 x 20 (pin bearing)
6306
63/28
SD - 30 - 45 - 5
S7 - 14 - 27 - 6
6000
S - 10 - 21 -5
15NQ2815
15NQ2815
6303
6272
SD8 - 32 - 52 -7
6005
6202Z
6205
6302
SD8 - 32 - 52 -7
Component
Thermostat valve :
Type/manufacturer.
Valve opening temperature.
Full valve opening temperature.
Full valve opening stroke.
Rating
4HC/NIHON THERMOSTAT
80,5 ~ 83,5 °C
95 °C
3 mm
02 / 07Chap.2

aprilia
YP 250 4T
Release 02 / 2000 - 05
OIL CHART
Engine oil (recommended): SUPERBIKE 4, SAE 5W - 40.
4T Formula Racing
Or alternatively branded oils with equivalent or better performance than CCMC G-4, A.P.I.
SG.
Transmission oil (recommended): F.C SAE 75W - 90.
Gear Synth
Or alternatively branded oils with equivalent or better performance than A.P.I. GL4.
Bearings and othergrease points (recommended): AUTOGREASE MP.
Grease 30
Or alternatively branded greasefor revolving bearings with temperature range of -30 °C
to+140 °C, dripping point 150 °C + 230 °C, with highprotection and anti corrosion
properties, good resistance to water and oxidation.
03 / 01Chap.3
Refrigeration liquid for the engine (recommended):
ECOBLU - 40°C or COOL

aprilia
YP 250 4T
Release 02 / 2000 - 05
SPECIAL ENGINE TOOLS
Drawing Tool code Name/function
Multi-purpose tool for Yamaha 250/Piaggio/Leonardo for
disassembly of the ignition clutch Unit.
8140252
8140228
8140393
8140259
Plate for extracting the flywheel (YP 250 + Aprilia 50).
04 / 01Chap.4
Tool for protection of the drive shaft, flywheel side
Tool for disassembly and assembly of clutch unit
universal joints

aprilia
YP 250 4T
Release 02 / 2000 - 05
CARBURETTOR
DISASSEMBLY
SEQUENCE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
ITEM NAME
Cold starter (automatic)
Accelerator block screw
Idling adjustment screw
Diaphragm cap/spring
Piston valve
Cone-shaped pin unit
Enrichment diaphragm
Acceleration pump
Float tank
Float pin
Float
Pin valve
Max. jet
Min. jet
Atomizer
11
14
3
9
8
10
15
13
12
2
4
7
5
6
1
05 / 01Chap.5

aprilia
YP 250 4T
Release 02 / 2000 - 05
Turn the primary pulley in anti-clockwise
direction until point (a) is lined up with point
(b).
ENGINE TIMING
Fit the distribution chain to the camshaft pinion, make sure the distribution chain on the discharge
side is as tight as possible.
N.B. When fitting the camshaft pinion, make sure the distribution chain on the discharge side is
as tight as possible.
SETTING THE ENGINE TIMING
06 / 01Chap.6
Line up point I (c) on the camshaft pinion
with point (d) on the cylinder head.

aprilia
YP 250 4T
Release 02 / 2000 - 05
VALVE PLAY (cold)
ASPIRATION 0.08  0.12 mm
DISCHARGE 0.16  0.20 mm
CONTROL PROCEDURE
Turn the primary pulley in an anti-clockwise
direction so that notch a on the rotor is lined
up with point b on the engine cap when the
piston is in the upper dead center position.
Measure valve play with a thickness gauge.
Adjust if if out of spec.
ADJUSTMENT PROCEDURE
Loosen the lock nut (1).
Tighten or loosen the adjuster (3) until the
play is as specified.
ADJUSTING VALVE PLAY
06 / 02Chap.6

aprilia
YP 250 4T
Release 02 / 2000 - 05
Communication no: 11 / 1999 Info classification Date: 29/04/99 Page: 1/10
Model: Currently with: Signature
New models 1999
LEONARDO 250
Dealer
manager
Re: Workshop
manager
INFORMAZIONI UTILI PER LA MANUTENZIONE E LASSISTENZA
NUOVI VEICOLI Warranty
Ref. Training course ITP9901 manager
Technical information: This document contains information about the 1999 models discussed
during the recent IT NP 9901 training course.
MODEL LEONARDO 250
OIL WARNING SERVICE LIGHT:
The engine oil light on the Leonardo 250 is a service light. It is not connected to a pressure gauge and
does not come on if the oil pressure goes down to a critical level.
The light comes on occasionally on the basis of engine drive shaft rotations as measured by the
electronic pick-up. See the operations and maintenance handbook for details (chart shown on this
fax).
To reset the light, press the hidden pushbutton under the saddle, on the right side of the battery
housing, as shown in diagram 1. The operations and maintenance handbook DOES NOT include
this information (it is therefore a service operation). Press the pushbutton until the light goes off.
M
S
QUALITY
MEASUREMENT
SYSTEM
MICRO SWITCH
TECHNICAL OBSERVATIONS
07 / 01Chap.7

aprilia
YP 250 4T
Release 02 / 2000 - 05
For any further information contact Technical Services at the following numbers:
Fax: **39 - 041 - 5786260
Tel: **39 - 041 - 5786262 / 6264
aprilia consumer service
Technical and Training Services
Santa Maria di Sala (Venice)
Information: Technical communications are numbered in chronological order. File them in the same order. For back Numbers contact the
numbers shown above.
How to check the OIL
For the Leonardo 125 e150, the oil level
rod should be tightened.
For the Leonardo 250 the oil level rod
should be as shown in the diagram.
M
S
QUALITY
MEASUREMENT
SYSTEM
125
150
250
MAXMAX
MINMIN
1
2
07 / 02Chap.7

CHECKING WEAR LIMITS
Chart references Component Wear limit
DISASSEMBLY SEQUENCE
REMOVING THE TRAPEZOID BELT, THE CLUTCH AND
PRIMARY/SECONDARY PULLEY.
Remove the variator cap (2) screws (1) and gasket
Remove the 6-sided nut (3) and washer (4)
Remove the primary fixed pullet (5)
Remove the 6-sided nut (6) and remove the clutch drum (7)
Remove the clutch from the transmission shaft (28)
Remove the trapezoid belt (10)
Remove the primary mobile pulley (11) and the bush (12)
Removetheprimary pulley caps (13), the rampplate(14)and
the 8 centrifugal masses (15)
Remove the slider (16) and spacers (17)
Remove the oil guard (18)
DISASSEMBLY THE CLUTCH UNIT
Remove the nut (8)
Remove the complete centrifugal clutch (9), the compression
spring (19) and spring cap (20)
Slide off the guide pins (21)
Remove the secondary mobile pulley (22)
Removethe 2 O-rings (23) and 2oil guards (24)aswell asthe
fixed secondary pulley (25)
REMOVING THE TRANSMISSION
Remove the screws (26) and transmission cap (27)
Slide off the transmission shaft (28)
Remove the flat washer (29) (30) and gear (31)
Slide off the driven shaft and intermediate gear (33)
Remove the primary driven gear (34) and flat washer (35)
9 Clutch jaws
10 Trapezoidbelt
15 Variator roller
Thickness: 2 mm (originale thickness 3 mm)
Width: 21mm (original width 22,6 mm)
Outer diameter 19.5 mm (original diameter: 20 mm)
21
20 19
22
87
24
9
2
1
23
10
6
3
33
11
28
18
32
30
16 Nm (1.6 Kgm)
60 Nm (6.0 Kgm)
3 Nm (0.3 Kgm)
10 Nm (1 Kgm)
60 Nm (6.0 Kgm)
90 Nm (9.0 Kgm)
31
34
35
25
15
16
4
27
26
12
14
N
N
N
N
G
G
G
G
G
G
G
G
G
5
17
13
29
O.C.
O.C.
OBM
O.C.
O.C.
24
O.C.
OM
OM
G
: Engine oil
: Change oil
: Grease
: New item
: Molibdenum Bisulphate Oil
N
REASSEMBLY
Reverse the order of disassembly instructions, making sure
tightening torques are correct, and all components requiring
grease are greased or, if necessary, replaced with
components specified in the table.
RELEASE 02 2000 - 05 YP 4T
TABLE 01
TRANSMISSION

CHECKING WEAR LIMITS
Chart references Component Wear limit
DISASSEMBLY SEQUENCE
CYLINDER HEAD
Remove the oil discharge cap (1A)
Remove the distributor cap (1) and O-ring (2)
Remove the valvecapon theaspirationside (3) anddischarge
side (4)
Remove the chain stretching unit (5)
Remove the breather plate (6)
Remove the distribution gear (7)
Remove the nuts (9) and bolts (10)
Remove thehead (11),cylinderheadgasket(12)andcentering
pins (13)
CAMSHAFT AND ROCKER ARMS
Remove the 2 screws (14), and the block washer (15) and
plate (16)
Remove the rocker arm pins from the aspiration valves (17)
and exhaust (18)
Remove the aspiration rocker arms (19) and exhaust rocker
arms (20)
Slide off the camshaft (21)
Remove the lock nuts (22) and adusters(23)
Remove the seal ring (24)
VALVES AND VALVE SPRINGS
Remove the valve half-cones (25), and upper plates (26)
Remove the inner springs (27) and outer springs (28)
Remove the aspiration valve (29) and exhaust valve (30)
Remove the valve guides (31) and lower plates (32)
CYLINDER AND PISTON
Remove the distribution chain guide on the discharge side
(33)
Slide off the cylinder (34), the centering pins (35) and the
cylinder base gasket (36)
Remove the piston rings (37),the piston pin (38)
Remove the piston (39)
Remove first the upper segment (40), then the lower segment
(41) and the scraper ring (42)
34 Cylinder
39 Piston
40 Uppersegment
41 Lowersegment
11 Head
Bore : 69,1 mm (originario : 69,000 - 69005 mm)
Piston/cylinder play : 0,02 - 0,04 mm
Distance from edge : 0,45 mm (original : 0,15 - 0,30 mm)
Distance from edge : 0,70 mm (original : 0,30 - 0,45 mm)
Deformation: < 0,03 mm
42
27
8 Nm (0,8 Kgm)
8 Nm (0,8 Kgm)
41
21
39
40
37
O.C.
OBM
OBM
OBM
OM
OM
OM
OM
G
: Engine oil
: Change oiol
: Grease
: Molibdenum Bisulphate Oil
37
7
6
2
1
4
10
1A
11
14
15
22
18
16
19
3
9
23 25 26 27 28
36
13
35
34
12
30
28
26
25
23
33
20
22
29
32
31
17
24
5
8 Nm (0,8 Kgm)
60 Nm (6 kgm)
10 Nm (1 kgm)
22 Nm
(2.2Kgm)
38
OM
G
OM
N
N
N
N
N
N
N
N
N
N
: New item
N
REASSEMBLY
Reverse the order of disassembly instructions, making sure
tightening torques are correct, and all components requiring
grease are greased or, if necessary, replaced with
components specified in the table.
RELEASE 02 2000 - 05 YP 4T
TABLE 02
HEATING UNIT