Editing Yamaha XJ900F

{{Infobox Motorcycle
|name             = [[Yamaha]] XJ900
|image            = [[File:Yamaha-XJ900F-85--1.jpg|frameless|Yamaha XJ900]]
|aka              = XJ900F, XJ900S Diversion, XJ 900 S Diversion, XJ 900 S, XJ 900 F, XJ 900, XJ900S
|manufacturer     = Yamaha
|parent_company   =
|production       = 1985 - 89
|model_year       =
|predecessor      =
|successor        =
|class            =
|engine           = Four stroke, transverse four cylinder, DOHC, 2 valves per cylinder.
|bore_stroke      =
|compression      = 9.6:1
|top_speed        = 193.1 km/h
|power            =
|torque           =
|fuel_system      =
|ignition         = CDI
|spark_plug       =
|battery          =
|transmission     = 5 Speed
|frame            = Steel tubular
|suspension       =Front: 37mm Telescopic fork <br>
Rear: Twin shock, Swingarm
|brakes           =Front: 2x 267mm discs <br>Rear: Single 267mm disc,
|front_tire       = {{tire|100/90-18}} 
|rear_tire   	  = {{tire|120/90-18}} 
|rake_trail       =
|wheelbase        = 1480 mm / 58.2 in
|length           = 2260 mm / 88.9 in
|width            =
|height           =
|seat_height      = 780mm / 30.7 in
|dry_weight       =
|wet_weight       = 244 kg / 537.9 lbs
|fuel_capacity    = 22 Litres / 5.8 US gal
|oil_capacity     =
|fuel_consumption =
|turning_radius   =
|related          =
|competition      =
}}

It could reach a top speed of 193.1 km/h.  

==Engine==
The engine was a Air cooled cooled Four stroke, transverse four cylinder, DOHC, 2 valves per cylinder.. The engine featured a 9.6:1 [[compression ratio]].  

==Drive==
Power was moderated via the Wet, 6 springs.  

==Chassis==
It came with a 100/90-18 front [[tire]] and a 120/90-18 rear tire. Stopping was achieved via 2x 267mm discs in the front and a Single 267mm disc, in the rear. The front suspension was a  37mm Telescopic fork while the rear was equipped with a Twin shock, Swingarm. The XJ900F was fitted with a 22 Litres / 5.8 US gal fuel tank. The wheelbase was 1480 mm / 58.2 in long.  
== Photos ==
[[File:Yamaha-XJ900F-85--1.jpg|600px|Yamaha XJ900]]
[[File:Yamaha-XJ900F-85--2.jpg|600px|Yamaha XJ900]]
[[File:Yamaha-XJ900F-85.jpg|600px|Yamaha XJ900]]

== Overview ==

Yamaha XJ 900F


















Sensible bikes are small, and
motorcycles never have long production runs. As generalisations, it's fair
to say that these are mostly true, but then along comes Yamaha's XJ900 to be
the exception to prove the rule -whatever that means. For this air cooled,
transverse four cylinder machine has been churning out of the Hammamatsu
factory for almost exactly a decade,now,
and with an engine capacity that's anything but small. At its launch at the
end of 1982, the XJ appeared to be aimed at filling the sports-tourer role,
but at first fell between the two stools rather than straddling them
confidently. Shaft drive gave the lie to any sporting credentials in many
people's eyes, while the small, bar mounted nose fairing wasn't really
adequate for a proper tourer. In addition, the first models were found to
have
a high speed weave problem, serious enough for them to be recalled for a
frame mounted, slightly larger version of the fibre to be fitted which has
appeared on every XJ since. But gradually, over the years, the 900's
positive qualities have taken the upper hand, and it's since sold steadily
enough to be retained for a whole decade in the Yamaha line up (let me tell
you, one dealer I've spoked to this year has sold four XJs, no GTSs and no
YZFs. Modifications over the years have been relatively few; after the
fairing change, in February 1985 the bore was increased from 67 to 68.5 mm,
raising capacity from 853 to 891 cc and upping the low rev torque usefully,
as well as improving the top end power slightly. Other changes have been
mostly cosmetic, though very recently, the clocks have finally been moved
from the handlebars to a console on the inside of the fairing. Though now
old fashioned in many respects, the XJ900 still has some qualities yet to be
taken on board by some other bike designers.
The generous 4.8 gallon fuel
tank and 45 to 55 mpg consumption allow two hundred miles to be covered
before the reserve tap even needs to be cocked, and the roomy riding
position doesn't make this a particular feat of endurance, though the
forward slope of the seat is less than ideal. Low down torque is excellent,
enough for the bike to comfortably pull from two thousand rpm in top gear,
making for a relaxed, long legged feel. In fact revving it is nothing like
as satisfactory anyway, mainly because the motor becomes harsh and vibratory
when spun much above six thousand.
But another feature which
appeals to
potential XJ buyers is the relatively simple servicing requirements. After
all, at £4500 new, the Yamaha is clearly a budget machine, so will already
have attracted the home mechanic or at least those competent enough to
affect roadside repairs. The first advantage the XJ has over more recent
designs is immediately obvious - the engine and ancilliaries are very much
more acce-sible, so far less time is spent in simply getting to the parts
you want to look at. What does have to come off, almost inevitably, is the
fuel tank, but before that remove the seat (undo the lock then operate the
two levers under it on either side at the back). The sidepanels can now be
pulled off, and practically the same procee-dure applies to the tank.
Instead of bolts at the back, only a spring clip needs to be pulled out
before the back of the tank can be lifted. The fuel tap should be left in
the 'On' or 'Reserve' position and the fuel and vacuum pipes to it
disconnected, as well as the electrical connecter from the fuel level
sender.
Once the tank is off, it's worth
smearing a little grease on the two locating rubbers at the front, to make
life a lot easier when it comes to replacing it. The fairing doesn't have to
come off, though many people assume otherwise -instead remove the two 6 mm
bolts at the back of it, near the engine,- as there's enough flexibility in
the panels for them to be bent out of the way when necessary. Dave Sterry at
Hamil-tons in Streatham, who kindly did the necessary to this particular XJ
for us, then prefers
to blow around the spark plugs with an airline to clear any muck and grit
away -if it falls into the cylinders it can cause a lot of damage. You
probably don't have an airline at home, so either do the same with a
footpump (or even bicycle pump) or blow through a piece of tubing. This of
course applies to any bike you're removing the plugs from, not just the
XJ900. The small, vestigial-looking belly pan comes away after the four
Phillips screws attaching it are undone, and the bike's now ready for your
attentions.
Working down the engine, the
spark plugs themselves are very easily taken out (with or without the fuel
tank in place) as they're angled towards the outside of the engine. The
leads are not only numbered one to four from left to right, but color coded
as well in case the numbers wear off, so there's not much excuse for putting
them back wrongly. In fact, the plugs last well, as long as fifteen thousand
miles if the bike's not used too hard. Next, if the engine's cold, the valve
clearances can be adjusted. The cam cover is held on by eight bolts with 10
mm heads and 6 mm threads, with thick rubber washers to seal them. All are
very easy to get at, and all are the same. Once they're out, the cover
itself lifts off and will come quite easily away out of the left hand side
of the engine, exposing the eight valves and their shimmed clearance system.

The shims are on top of the
valve buckets, so the cams themselves don't need to be disturbed. If you
want to play safe, undo the left hand crankshaft end cover, so the timing
marks can be seen, and align the T' scribe with the line on either side of
the ignition pickups. Two of the cylinders will be at top dead centre, and
one of those in its compression stroke, when the cam lobes will be facing
away from the valves. That's the cylinder to work on first, so check with a
feeler guage that the inlet valve clearance is between 0.11 and 0.15 mm, and
the exhaust between 0.16 and 0.20 mm. If one is outside the tolerance,
you'll need to replace the shim with a fatter or thinner one to bring it
back (usually you'll be after a thinner shim, as the gaps tend to close up
in use). If you're not confident about levering the valve down, clear of the
cam, with whatever you have lying around your shed, you'll need the special
Yamaha lifting tool, which isn't an exorbitant price. First rotate the
bucket so the notch in its rim is easily accessed - you'll need this to lift
out the shim, so make sure you can get an electricians' screwdriver to it.
Then turn the engine over (stabbing at the starter button is fine, as long
as the plugs are d i s c o n -nected...) until the valve you're working on
is fully opened by the cam, and insert the tool into position behind the cam
lobe, so it rests on top of the valve (locating on the edges of the bucket)
and bolt it to whichever cam cover bolt hole is nearest (it'll only align
with one). Be sure that it's completely square on to the cam. Now turn the
engine over again so the cam lobe moves back to facing away from the valve,
which the tool should still be holding fully open. If you've turned the
engine so the cam lobe moved away from the tool, then you'll be busy lifting
out the shim. If you rotated the engine the other way, the valve lifting
tool will have obstructed the cam lobe, and part of the cylinder head could
have snapped off, (seriously) so you'll be busy phoning your local Yamaha
dealer to discover that a new one, without the labour costs of swapping over
your cams and valves or fitting it, costs a breathtaking £1031.25. Still,
that includes VAT, so it could be worse...
Definitely worth noting. Anyway,
the shim can now be lifted out with the dextrous use of pliers and fine
screwdriver, and hopefully its thickness will be inscribed on the back. If
not, it was fitted the wrong way round and this wore off, so you'll need
(...to get a dealer...) to measure it with a micrometer. Then the size of
the new shim can be calculated. Once all the needy valves are seen to
(usually only one or two at each service) the cam cover can be replaced. The
rubber gasket will still be sitting snugly in its groove in the cover, and
doesn't need to be replaced or assisted with any gasket cement, though it's
worth cleaning up the rubber washers on the cover bolts, as with even a
small piece of grit, they'll start to weep oil. Replace the timing cover,
too.
Now the enigne can be started
and fully warmed so the carbs can be balanced. This is quite conventional,
apart from the fact that a special tool is needed again to blank off the
YICS valves. These are passages within the cylinder head linking the inlet
tracts and which have a significant effect in boosting the low and mid-range
power of the motor, but do interfere with carb balancing. Remove the bolt in
the left side of the cylinder block, insert the special toll and crimp over
the end - the passages are now suitably blanked off, and the vacuum gauge
pipes can be connected to the brass stubs on top of the inlet tracts. On
cylinders one, two and four these normally have rubber caps on, while the
third cylinder's is connected to the fuel tap vacuum switch, but note that
on older bikes the rubber hardens and cracks, so that air can leak into the
inlets and upset the carburation. Replace them with new if you're in doubt.
If you're using the fuel tank remotely, you'll have to set the tap to the
'Prime' position, or there'll be zero flow, but Dave Sterry uses an old oil
bottle which holds enough gas for the balancing operation. The recommended
method is to balance cylinders three and four to each other, then one and
two to each other, and finally equalise the two pairs of cylinders with the
central butterfly adjuster. If you can get all the carbs to read within 1 cm
of mercury of
each other (the absolute value
is unimportant, unless it's obviously absurd and needs investigating) that's
ideal, but 2 cm is acceptable. The carburetor air mixture screws are
located on tops of the bodies, just to the engine side of the diaphragm
housings, and are covered by rubber plugs. These don't normally need
attention until the engine's covered quite a high mileage, but do ensure the
plugs are securely in place, as otherwise water gets to the mixture screws
and they seize up - the only cure when they do need to be moved is to drill
them out, and that often doesn't work.

Now that the engine's fully warmed, the oil and filter can be replaced. The
drain plug is well hidden but accessible with a socket wrench beneath the
filter housing, which itself is on the lower front of the crankcases. That
won't come out directly through the exhaust pipes, but needs to be twisted
to one side first -you don't have to take the pipes off though...
The motor needs no more attention than this, as even ten years ago
electronic ignition and automatic cam chain tensioning were the norm, so you
can move onto the rest of the machine. Starting at the front, the brakes are
prone to seizing during winter use (aren't they all on Yamahas?) so even if
the pads aren't worn it's worth removing them and cleaning up the callipers.
This involves extracting the bent over 'R' clips in the pins, sliding out
the front one, lifting off the spring plate then sliding out the rear pin.
The pads should now come out, though some makes (EBC, for example,) can be a
tighter fit than others. If you're applying Copa-slip -which is worthwhile
if done sparingly -add a touch to the sides of the pads as well as the back
to get them operating more smoothly (Dave Sterry's recommendation again).

Under the left sidepanel (which
should already be off...) is the air filter housing, though you'll have to
unclip the toolkit holder before removing the four Phillips screws that hold
the cover on. The filter itself now comes out easily enough, but as it's
paper will have to be renewed rather than cleaned, and at about seventeen
pounds a time isn't cheap. On the other hand, even at something like five
thousand miles old it can affect fuel consumption noticeably, so don't leave
it too long - it's a false economy. A K& N washable airbox filter is
available for the XJ9, so if you're keeping the bike for a while, is a good
investment. Meanwhile, make sure the lip in the edge of the filter (on each
side) engages properly with the slots in the housing and cover, or again the
carburation will be upset by airleaks. On the other side of the bike is the
battery, which is very visible so checking the level isn't a chore.
At the back the shaft drive bevel box oil should ideally be changed at each
service, with an EP80 or 90 gear oil. The drain plug is on the bottom, while
the filler plug is halfway up, and this also doubles as the level check -
fill the oil to the bottom of the threads and no more. Overfilling causes
oil to blown out of the breather (the domed nut on top of the housing) and
all over the rear wheel, in which case you might as well have opted for
chain drive in the first place...
Source Witch Motorcycle 1993





{|  class="wikitable"
|- 
!Make Model
|Yamaha XJ 900F
|- 
!Year
|1985 - 89
|- 
!Engine Type
|Four stroke, transverse four cylinder, DOHC, 2 valves per cylinder.
|- 
!Displacement
|891 cc / 54.3 cu-in
|- 
!Bore X Stroke
|68.5 x 60.5 mm
|- 
!Cooling System
|Air cooled
|- 
!Compression
|9.6:1
|- 
!Induction
|4x Mikuni BS36
|- 
!Ignition
|CDI
|- 
!Starting
|Electric
|- 
!Max Power
|98 hp / 72 kW @ 9000 rpm
|- 
!Max Torque
|81 Nm / @ 7000 rpm
|- 
!Clutch
|Wet, 6 springs
|- 
!Transmission
|5 Speed
|- 
!Final Drive
|Shaft
|- 
!Frame
|Steel tubular
|- 
!Front Suspension
|37mm Telescopic fork
|- 
!Rear Suspension
|Twin shock, Swingarm
|- 
!Front Brakes
|2x 267mm discs
|- 
!Rear Brakes
|Single 267mm disc,
|- 
!Front Tire
|100/90-18
|- 
!Rear Tire
|120/90-18
|- 
!Rake
|27°
|- 
!Trial
|120 mm / 4.5 in
|- 
!Length
|2260 mm / 88.9 in
|- 
!Wheelbase
|1480 mm / 58.2 in
|- 
!Seat Height
|780mm / 30.7 in
|- 
!Ground Clearance
|145mm / 5.7 in
|- 
!Wet Weight
|244 kg / 537.9 lbs
|- 
!Fuel Capacity
|22 Litres / 5.8 US gal
|- 
!Consumption Average
|44.1 mph
|- 
!Standing ¼ Mile
|12.1 sec / 175.4 km/h
|- 
!Top Speed
|193.1 km/h

|}

[[Category:Yamaha motorcycles]]