Untitled

The middleweightmotorclclr
Already hailed by the world's motorcycle
press as one of the best "middleweight" machines on the market, Yamaha's XS40O goes
one better this year by growing from its
former 358 cc capacity to the more-beefy
400 cc range.
With 38.0 horsepower (27.9 kW) there at
the rider's command, the XS400 packs a
heavyweight punch in an eminently-handleable middleweight package- It is one of the
very best of what people today have come
to call "urbo-bikes" or "commuter bikes"These are machines which will happily serve
a s a workho rse d urin g th e week . t ak ing t he
rider in perfect safety and comfort to and
from the office or factorv. Then thev are
c a pable of ab rup tly cha ng ing c har ac t er when
the weekend comes around. Of turning into
the type of sporting or iong-distance touring
motorcycle that signifies "real motorcycling"
to most enthusiasts.
For those weekends on the ooen road. the
c o mbinat ion of th e XS400' s iwin c y linder
engine and six speed gearbox will whistle
the rider along at over 90 mph. And for those
trips through town to the office there are such
welcome features as a three-phase electromagnetic field coil system that will keep the
battery fully charged even in "stop-go" tra{nc
and on short runs. Electric starting and an
automatic "no-flooding" fuel tap takes the
drudgery out of bringing the XS4O0 power
unit to life while a single adjustment screw
synchronises both carburetors.
The buyer of a motorcycle in today's world
d o e sn' t wa nt to waste t im e on c ons t anl
service. He wants a machine that he can ride
w i thout any ma inte na nce wor r ies .
The XS4OO fills that requirement and does
s o while still b ein g ca pa ble of ov er 90 m ph
on the open road or covering literally thousands of inner-city commuter runs between
servlces.
lf there was ever a bike for "everyman", that
bike is Yamaha's XS4O0.
Engine
The 391 cc power unit has a bore and stroke
o f 69. 0X 52 .4mfn an d put s out 38. 0 hor s epower (27.9 kW) with a tractable torque
curve to match. Pressure-lubricated bie-end
b earings a re of the she ll t y pe and a geår on
the centre of l 8O degree crankshaft drives the
single overhead-camshaft.
Carburettors
T h e t w i n 3 4 m m M i ku n i ca r b u r e tto r s a r e
pre-set at the assembly stage to the demands
of the XS400 power unit and operate on the
v a c u u m p r i n c i p l e . Th i s m e a n s th a t th e ca r b u rettors never deliver more gas to the engine
t h a n i t a c t u a l l y r e q u i r e s a n d r e su l ts i n m u ch
better fuel-economy. Setting the carburettors
is simplicity itself (one screw synchronises
t h e m ! ) a n d t h e y r e q u i r e m i n i m u m a tte n ti o n
while delivering maximum efficiency.
Frame
Yamaha have learned a great deal about
frame design from therr super-successful
efforts in Grand Prix road racins and the
XS4O O c h a s s i s i s o b v i o u s l y b a s e J o n t h e s e
les s on s . l t i s f u l l d u p l e x c r a d l e , w i t h t h e e n gine m o u n t e d l o w d o w n f o r m a x i m u m
handleability. A low centre of gravity means
that a rider can swing the Yamaha XS400
from lock to lock much easier when negotiating t r a f f i c . . . a n d t h a t t h e w h o l e m a c h i n e
will be much more stable at higher speeds.
Transmission
The c h o i c e o f a s i x - s p e e dt r a n s m i s s i o n m e a n s
that the rider can make full use of the added
punch of the new 400 cc version of the XS
four-stroke power plant.
The lower five gears have ratios specifically
des ign e d w i t h v i v i d a c c e l e r a t i o n i n m i n d .
The sixth (top) gear has a different purpose.
I t is a n " o v e r d r i v e " t h a t a l l o w s a r i d e r t o
c r uis e a t l o w e r e n g i n e r e v o l u t i o n s o n c e h e
has got up to a good cruising speed.
The benefits of this "overdrive" so3r are twof old. F i r s t . i t m e a n s i m p r o v e d i u e l e c o n o m y
wit hou t d e c r e a s i n g a c t u a l c r u i s i n g s p e e d s .
Sec on d l y , t h e l o w e r e n g i n e r e v o l u t i o n s n e e d ed t o a t t a i n a n y g i v e n s p e e d w i l l r e s u l t i n
longer e n g i n e l i f e a n d m o r e t i m e b e t w e e n
servlces.
Front Forks, Rear Suspension
T h o u g h w e l l - c o n tr o l l e d i n th e i r a cti o n a n d
giving good, firm steering, the front forks
are softly-sprung for maximum comfort. This
a i m i s a l s o a i d e d b y th e l 4 0 m m o f fo r k
travel and by the smooth fork action that
results from the use of anti-friction Teflon
s p e c i a l f o r k b u s h i n g s.
T h e v i s u a l l y - e x c iti n g l o o k o f th e XS4 OO i s
enhanced by the use of exposed chrome
s p r i n g s o n t h e r e a r su sp e n si o n u n i ts. Ad d i tionally, these units have five load settings
to compensate for any weight changes or
u n u s u a l u s a g e c o n d i ti o n s.
Disc Brakes
The XS4O0 has stopping power to match its
f o r w a r d m o t i o n ! Po si ti ve - a cti n g 2 6 7 m m d i sc
brakes, hydraulically-operated on both front
and rear wheels.
Cast-Alloy Wheels
Though it is an ultra-reliable mode of transportation, the X5400 is also an exciting
m o to r cycl e . . . a n d l o o ks i t. Th i s l o o k i s
emphasised by the use of seven-spoke cast
alloy wheels which other manufacturers may
offer as "options" but which Yamaha fit to
the XS400 as standard equipment ! Easy to
clean, easily balanced after tyre changes
( Ya m a h a d yn a m i ca l l y b a l a n ce b o th w h e e l s
at the assembly stage) and visually superb,
th e ca st w h e e l i s th e co m i n g th i n g i n m o to r cycle design. On the XS400 you have the
w h e e l o f th e fu tu r e . . . n o w !
gets L heavyweightpunch!
Handlebar
T h e " c o n t i o i p a n e l " o f th e Ya m a h a XS4 0 0 g i ve s a n i m m e d i a te cl u e to th e
l e n g t h s t o w h ich Ya m a h a h a ve g o n e to m a ke th e m e ch a n i cs o f r i d i n g so e a sy
t h a t t h e r i d e r ca n p e r fo r m th e n e ce ssa r y fu n cti o n s a l m o st a u to m a ti ca l l y.
A t t h e r i d e r 's fi n g e r ti p s a r e th e m a i n l i g h t sw i tch e s. th e d i p sw i tch , h e a d l a m p
f l a s h s w i t c h , el e ctr i c sta r t b u tto n , e n g i n e sto p sw i tch . a n d th e co n tr o l s fo r
Y a m a h a 's u n i cu e se l f- ca n ce l l i n s tu r n i n d i ca to r s. Th e se a r e ti m e d to a u to m a ti c a l l y s w i t c h t h e m se l ve s o tl 'a fte r th e r i d e r h a s co m p l e te d h i s tu r n ! H a n d l e b a r
l e v e r s a r e o f th e n e w "Be l l - cr a n k" typ e fo r e a sy o p e r a ti o n vi a th e i r e xtr a - l e ve r a g e c a p a b i l 'i t i e s. l n th e ce n tr a l i n str u m e n t co n so l e a r e th e sp e e d o m e te r a n d
s m o o t h - o p e r a t in g ta ch o m e te r , l o w o i l p r e ssu r e w a r n i n g l i g h t a n d n e u tr a l
l no lcator.
Lighting
Ihe XS400 lighting system throws out a
engthy beam for open road riding but also
or o v i d es maxim u m pe riph era l illum inat ion
:o cope with all night-time traffic conditions.
l us t a s import ant; we ll-de sig ned and br ight
'ear lights, turn signals and reflectors make
i ure t h at t he ride r is hishlv vis ible t o ot her
:raffic. An exclusive-toYamaha feature is the
;elf-cancelling turn inlicators that automati:ally switch off after
:he turn is completed.
Se a t
Whether it's for reasons of transportation
or for excitement, the Yamaha XS400 owner will spend a long
time in the saddle. Yamaha designers realised this and designed
t he s t y lis h s e a t u n i t f o r m a x i m u å c o m f o r t w i t h t h e a c c e n t 6 n u
wide, deep s e a t c u s h i o n a n d p o s t u r e - c o n s c i o u s p o s i t i o n i n g .
*-#
g
xs400
SPECIFICATIONS
EN G IN E
Type .
. . .4-stroke,Tw i n, OH C
D i s p l a c e m e n t...
Bore& Stroke...-_..
69.0x52.4mm
C o mp re s s i o nra ti o ... -- :P :.
Max. horsepower..
9.4: I
38.0HP (27.9kW)
revlmin
@8,800
3.3kg-m(32.4Nm)
@8,000revlmin
M a x . to rq u e .
Lubrication system
Starting system
P ri ma ry tra n s m i s s i o n ... ..
F i n a l tra n s m i s s i o n.
Ge a rb o x
Carburettor
C l u tc h .
Battery
C h a rg i n g s y s te m. ... :
Ig n i ti o n ty p e .....
D IME N S IO N S
Overall length .
Ov e ra l l w i d th ..........\
Overall height
Wh e e l b a s e
Se a th e i g h t
We i g h t (n e t).. . .. ....."
F u e l ta n k c a p a c i ty .. . .
Oi l c a p a c i ty
Tire front.
re a r...
Brakes front. .
re a r.. .
* Specifcations subject to chan:g:i
<t
'@
wet sump
.Pressure-fed
. Electric& Kick starter
6-speed
Mi kuni ,B S 34(X 2)
Mul ti -pl ate,w et
12v, 12AH
.. . A .C . Generator
.. B attery,C B /C oi l
2,020mm
730mm
1,070
mm
1,335
mm
815 mm
164kg
2.6l i t.
3.00s-r8-4PR
3.50S-r
8-4PR
[ .......H yd. di sc,di am. 267 mm
i i t1' .. ...H Y d' di sc,di am. 267 mm
't notice.
YAMAHA MOTORN.V.
3
iH:lff?ilJx3å"ky"lil:Hr'aan
LIT-3MC'o1 07 144-78E.BK/52.1Ox359.5O Printed in Japan ( r - a y,i)
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