Jet YAMAHA WR 450F 2003 Workshop Manual

TUN
ACHTUNG:


Der Vergaser ist extrem emp-
findlich gegen Fremdkörper
(Schmutz, Sand, Wasser usw.).
Darauf achten, daß bei der Mon-
tage keine Fremdkörper in den
Vergaser gelangen.

Mit dem Vergaser und seinen
Bauteilen immer vorsichtig
umgehen. Selbst leichte Kratzer,
Krümmungen oder Beschädi-
gungen an Vergaserteilen kön-
nen zu Fehlfunktion des
Vergasers führen. Alle War-
tungsarbeiten mit geeignetem
Werkzeug und ohne übermäßi-
gen Krafteinsatz durchführen.

Wenn der Motor steht oder ohne
Last dreht, den Gasdrehgriff
nicht unnötig öffnen und schlie-
ßen. Andernfalls wird zuviel
Kraftstoff geliefert, was das
Anlassen erschwert oder den
Motorlauf beeinträchtigt.

Nach der Montage des Verga-
sers prüfen, ob die Drossel-
klappe korrekt arbeitet und
leichtgängig öffnet und schließt.
Atmosphärische Bedingungen
und Einstellungen
Von der Luftdichte (die Sauerstoff-
konzentration in der Luft) hängt ab,
ob das Luft-Kraftstoff-Gemisch fett
oder mager ist. Beachten Sie
daher die obenstehende Tabelle
mit den Gemischeinstellungen.
Das heißt:

Eine höhere Temperatur führt zu
einer Ausdehnung der Luft und da-
mit zu einer geringeren Dichte.

Eine höhere Luftfeuchtigkeit redu-
ziert den Sauerstoffgehalt der Luft,
je mehr Wasserdampf die Luft ent-
hält.

Ein niedrigerer atmosphärischer
Druck (in großer Höhe) reduziert
die Dichte der Luft.
Luft-
temp.Feuch-
tig-
keitLuft-
druck
(Höhe)GemischEinstel-
lung
Hoch HochNiedrig
(hoch)FetterMage-
rer
Niedrig NiedrigHoch
(nied-
rig)Mage-
rerFetter
REGLAGE
EINSTELLUNG
AJUSTE
ATTENTION:


Le carburateur est extrêmement
sensible à toute pénétration de cras-
ses, sable, eau, etc. Bien veiller, lors
de tout travail sur le carburateur,
d’empêcher toute pénétration
d’objets quelconques.

Toujours manipuler le carburateur
et ses organes avec le plus grand
soin. Même de légères griffes, défor-
mations ou petits endommagements
peuvent empêcher son bon fonction-
nement. Effectuer soigneusement
tous les entretiens avec les outils
appropriés et sans recourir à une
force excessive.

Ne pas actionner sans raison la poi-
gnée des gaz lorsque le moteur est
coupé ou lorsqu’il tourne à vide. En
effet, cela provoquerait un apport
excédentaire en essence, rendant
difficile la mise en marche du
moteur ou entraînant son mauvais
fonctionnement.

Après la remise en place du carbu-
rateur, s’assurer que la poignée des
gaz fonctionne correctement.
Conditions atmosphériques et régla-
ges de carburateur
La densité de l’air, c.-à-d. la concen-
tration d’oxygène dans l’air, déter-
mine la richesse ou la pauvreté de
l’émulsion air/essence. Il convient dès
lors de se conformer au tableau ci-des-
sus.
La densité de l’air varie en fonction des
trois facteurs suivants:

La température de l’air: la densité de
l’air diminue au fur et à mesure que
l’air se dilate sous les températures
élevées.

Le taux d’humidité de l’air: le taux
d’oxygène diminue au fur et à mesure
que le taux d’humidité augmente.

Pression atmosphérique (altitude): la
densité diminue au fur et à mesure que
la pression atmosphérique descend
(altitude élevée).
Tempéra-
ture.HumiditéPression
atmosphéri-
que
(altitude)Emulsion Réglage
Haute HauteBasse
(haute)Plus richePlus pau-
vre
Basse BasseHaute
(basse)Plus pau-
vrePlus riche
7 - 2
ATENCION:


El carburador es extremadamente
sensible a los materiales extraños
(suciedad, arena, agua, etc.).
Durante la instalación, no permita
que se introduzca ningún material
extraño en el carburador.

Maneje siempre el carburador y sus
componentes con cuidado. Incluso
arañazos suaves, deformaciones o
daños pueden provocar que el car-
burador funcione incorrectamente.
Realice todo el mantenimiento con
las herramientas adecuadas y sin
aplicar una fuerza excesiva.

Cuando pare el motor o cuando
conduzca sin carga, no abra ni cie-
rre el acelerador innecesariamente
ya que podría descargarse dema-
siado combustible, el arranque
podría resultar difícil o podría no
funcionar el motor adecuadamente.

Después de instalar el carburador,
compruebe que el acelerador fun-
cione adecuadamente y que se abre
y cierra con suavidad.
Condiciones atmosféricas y ajustes del
carburador
La densidad del aire (es decir, la con-
centración de oxígeno en el aire)
determina la riqueza o pobreza de la
mezcla de aire y combustible. Por
tanto, consulte la tabla descrita ante-
riormente para observar los ajustes de
la mezcla.
Indicaciones:

Una temperatura más elevada expande
el aire dando como resultado una
reducción de la densidad.

Una humedad más elevada reduce la
cantidad de oxígeno en el aire debido
a la cantidad de vapor de agua del aire.

Una presión atmosférica más baja (en
una altitud elevada) reduce la densi-
dad del aire.
Tempera-
tura del
aire.HumedadPresión
del aire
(altitud)Mezcla Ajuste
Alta Alta Baja (alta) Más rica Más pobre
Baja BajaAlta
(baja)Más pobre Más rica

7 - 3
TUN

SETTING
Effects of the setting parts on the throttle
valve opening
1
Pilot screw/pilot jet
2
Throttle valve cutaway
3
Jet needle
4
Main jet
ÅClosed
ıFully open
1/2 3/4 1/4 1/8
1
2
3
4
Åı
Main system
The FLATCR carburetor has a primary main
jet. This type of main jet is perfect for racing
motorcycles since it supplies an even flow of
fuel, even at full load. Use the main jet and the
jet needle to set the carburetor.

1
Jet needle
2
Pilot air jet
3
Needle jet
4
Main jet
5
Pilot jet
6
Pilot screw

7 - 4
TUN

SETTING
Pilot system
The FLATCR carburetor is manufactured with
a pilot screw. The pilot screw adjustment
ranges from fully closed throttle to 1/4 open
throttle.
Main jet adjustment
The richness of the air-fuel mixture at full throt-
tle can be set by changing the main jet
1
.
* Except for USA
If the air-fuel mixture is too rich or too lean, the
engine power will drop, resulting in poor accel-
eration.
Effects of changing the main jet (reference)
Å
Idle
ı
Fully open
Standard main jet#150
*#160
1/4 1/2 3/4
+10%
#150
–10%
#160
#140
Åı

7 - 6
TUN

SETTING
Pilot jet adjustment
The richness of the air-fuel mixture with the
throttle open 1/4 or less can be set by adjust-
ing the pilot jet
1
.
* Except for USA
Effects of adjusting the pilot jet (reference)
Å
Idle
ı
Fully open
Jet needle groove position adjustment
Adjusting the jet needle
1
position affects the
acceleration when the throttle is 1/8 to 3/4
open.
1. Too rich at intermediate speeds
Rough engine operation is felt and the
engine will not pick up speed smoothly. In
this case, step up the jet needle clip by
one groove and move down the needle to
lean out the mixture.
2. Too lean at intermediate speeds
The engine breathes hard and will not
pick up speed quickly.
Step down the jet needle clip by one
groove and move up the needle to enrich
the mixture.
Effects of changing the jet needle groove
position (reference)
Å
Idle
ı
Fully open
1No.5 groove
2No.3 groove
3No.4 groove
Standard pilot jet#45
*#48
Standard clip position No.4 groove
1/4 1/2 3/4
+5%
–5%
#48
#42#45
Å
ı
1/4 1/2 3/4
+10%
–10%
1
23
ı Å

7 - 7
TUN
Jet needle adjustment
The jet needle is adjusted by changing it.
* Except for USA
The tapered sections of all jet needles have
the same starting positions, but the needles
are available with different straight-portion
diameters.Standard jet needleOBDUT
*OBDUQ

OBDUT - 4
Clip position
Diameter a of straight portion
Effects of changing the jet needle
(reference)
(Diameter of the straight portion)
Changing the diameter of the straight portion
adjusts the air-fuel mixture when the throttle is
1/8 to 1/4 open.
ÅIdleıFully open
Relationship with throttle opening
The flow of the fuel through the carburetor
main system is controlled by the main jet and
then, it is further regulated by the area
between the main nozzle and the jet needle.
The fuel flow relates to the diameter of the
straight portion of the jet needle with the throt-
tle 1/8 to 1/4 open and relates to the clip posi-
tion with the throttle 1/8 to 3/4 open.
Therefore, the fuel flow is balanced at each
stage of throttle opening by the combination of
the jet needle straight portion diameter, and
clip position.
1/4 1/2 3/4
+10%
T
–10%
S
U
Åı
SETTING

7 - 8
TUNSETTING
Carburetor setting parts
* Except for USAPart name Size Part number
Main jet Rich
*(STD)
(STD)
Lean#170
#168
#165
#162
#160
#158
#155
#152
#150
#148
#145
#142
#1404MX-14943-41
4MX-14943-91
4MX-14943-40
4MX-14943-90
4MX-14943-39
4MX-14943-89
4MX-14943-38
4MX-14943-88
4MX-14943-37
4MX-14943-87
4MX-14943-36
4MX-14943-86
4MX-14943-35
Pilot jet Rich
*(STD)
(STD)
Lean#52
#50
#48
#45
#42
#404MX-14948-08
4MX-14948-07
4MX-14948-06
4MX-14948-05
4MX-14948-04
4MX-14948-03
Jet needle Rich
(STD)
Lean#DUQ
#DUR
#DUS
#DUT
#DUU
#DUV
#DUW5TJ-14916-D1
5TJ-14916-DR
5TJ-14916-DS
5TJ-14916-DT
5TJ-14916-DU
5TJ-14916-DV
5TJ-14916-DW
Jet needle Rich
*(STD)
Lean#DUM
#DUN
#DUP
#DUQ
#DUR
#DUS
#DUT5TJ-14916-DM
5TJ-14916-DN
5TJ-14916-DP
5TJ-14916-D1
5TJ-14916-DR
5TJ-14916-DS
5TJ-14916-DT

7 - 9
TUN
Examples of carburetor setting depending on symptom
This should be taken simply for an example. It is necessary to set the carburetor while checking
the operating conditions of the engine.
Symptom Setting Checking
At full throttle
Hard breathing
Shearing noise
Whitish spark plug
Lean mixtureIncrease main jet calibration no.
(Gradually)Discoloration of spark plug →
If tan color, it is in good condition.
If cannot be corrected:
Clogged float valve seat
Clogged fuel hose
Clogged fuel cock
Check that the accelerator pump oper-
ates smoothly.
At full throttle
Speed pick-up stops
Slow speed pick-up
Slow response
Sooty spark plug
Rich mixtureDecrease main jet calibration no.
(Gradually)Discoloration of spark plug →
If tan color, it is in good condition.
If cannot be corrected:
Clogged air cleaner
Fuel overflow from carburetor
Lean mixture Lower jet needle clip position.
(1 groove down)
The clip position is the jet needle
groove on which the clip is installed.
The positions are numbered from the
top.
Check that the accelerator pump oper-
ates smoothly (except for rich mixture
symptom). Rich mixture Raise jet needle clip position.
(1 groove up)
1/4 ~ 3/4 throttle
Hard breathing
Lack of speedLower jet needle clip position.
(1 groove down)
1/4 ~ 1/2 throttle
Slow speed pick-up
Poor accelerationRaise jet needle clip position.
(1 groove up)
Closed to 1/4 throttle
Hard breathing
Speed downUse jet needle with a smaller diameter. Slow-speed-circuit passage
Clogged → Clean.
Overflow from carburetor
Closed to 1/4 throttle
Poor accelerationUse jet needle with a larger diameter.
Raise jet needle clip position. (1 groove
up)
Poor response in the low to
intermediate speedsRaise jet needle clip position.
If this has no effect, lower the jet needle
clip position.
Poor response when throttle
is opened quicklyCheck overall settings.
Use main jet with a lower calibration no.
Raise jet needle clip position.
(1 groove up)
If these have no effect, use a main jet
with a higher calibration no. and lower
the jet needle clip position.Check air cleaner for fouling.
Check that the accelerator pump oper-
ates smoothly.
Jet needleClip
Groobe 7 Groobe 6
Groobe 5
Groobe 4
Groobe 3
Groobe 2
Groobe 1
Leaner
↑
(Standard)
↓
Richer
*
SETTING