2001 YAMAHA WR 400F fuel

2 - 19
SPECGENERAL SPECIFICATIONS (WR400F)
Fuel:
Type Premium unleaded fuel with a research octane
number of 95 or higher. (Except for AUS)
Unleaded fuel only (For AUS)
Tank capacity 8.0 L (1.76 Imp gal, 2.11 US gal)
Reserve 1.4 L (0.31 Imp gal, 0.37 US gal)
Carburetor:
Type FCR-MX39
Manufacturer KEIHIN
Spark plug:
Type/manufacturer CR8E/NGK
U24ESR-N/DENSO
Gap 0.7 ~ 0.8 mm (0.028 ~ 0.031 in)
Clutch type: Wet, multiple-disc
Transmission:
Primary reduction system Gear
Primary reduction ratio 62/21 (2.952)
Secondary reduction system Chain drive
Secondary reduction ratio 50/14 (3.571)
Transmission type Constant mesh, 5-speed
Operation Left foot operation
Gear ratio: 1st 29/12 (2.416)
2nd 26/15 (1.733)
3rd 21/16 (1.312)
4th 21/20 (1.050)
5th 21/25 (0.840)
Chassis:
Frame type Semi double cradle
Caster angle 27.8˚
Trail 123 mm (4.84 in)
Tire:
Type With tube
Size (front) 90/90-21 54R
Size (rear) 130/90-18 69R
Tire pressure (front and rear) 100 kPa (1.0 kg/cm
2, 15 psi)
Brake:
Front brake type Single disc brake
Operation Right hand operation
Rear brake type Single disc brake
Operation Right foot operation
Suspension:
Front suspension Telescopic fork
Rear suspension Swingarm (link type monocross suspension)

2 - 33
SPECMAINTENANCE SPECIFICATIONS (WR400F)
NOTE:
- marked portion shall be checked for torque tightening after break-in or before each race.Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb
Rear brake hose union bolt (master cylinder)M10 ´ 1.25 1 30 3.0 22
Rear wheel axle and nut M20 ´ 1.5 1 125 12.5 90
Driven sprocket and wheel hub M8 ´ 1.25 6 42 4.2 30
Nipple (spoke) — 72 3 0.3 2.2
Disc cover and rear brake caliper M6 ´ 1.0 2 7 0.7 5.1
Protector and rear brake caliper M6 ´ 1.0 2 7 0.7 5.1
Engine mounting:
Engine bracket and frame M8 ´ 1.25 7 34 3.4 24
Engine and frame (front) M10 ´ 1.25 1 69 6.9 50
Engine and frame (upper) M10 ´ 1.25 1 55 5.5 40
Engine and frame (lower) M10 ´ 1.25 1 69 6.9 50
Engine guard (left and right) M8 ´ 1.25 2 23 2.3 17
Pivot shaft and nut M16 ´ 1.5 1 85 8.5 61
Relay arm and swingarm M14 ´ 1.5 1 80 8.0 58
Relay arm and connecting rod M14 ´ 1.5 1 80 8.0 58
Connecting rod and frame M14 ´ 1.5 1 80 8.0 58
Rear shock absorber and frame M10 ´ 1.25 1 56 5.6 40
Rear shock absorber and relay arm M10 ´ 1.25 1 53 5.3 38
Rear frame and frame M8 ´ 1.25 3 29 2.9 21
Swingarm and brake hose holder M5 ´ — 4 4 0.4 2.9
Drive chain tensioner mounting M8 ´ 1.25 2 19 1.9 13
Chain support and swingarm M6 ´ 1.0 3 7 0.7 5.1
Seal guard and swingarm M5 ´ 0.8 4 6 0.6 4.3
Fuel tank mounting M6 ´ 1.0 2 10 1.0 7.2
Fuel tank and fuel cock M6 ´ 1.0 2 7 0.7 5.1
Fuel tank and seat set bracket M6 ´ 1.0 1 7 0.7 5.1
Fuel tank and hooking screw (fitting band) M6 ´ 1.0 1 7 0.7 5.1
Fuel tank and fuel tank bracket M6 ´ 1.0 4 7 0.7 5.1
Seat mounting M8 ´ 1.25 2 23 2.3 17
Side cover mounting M6 ´ 1.0 2 7 0.7 5.1
Air scoop and fuel tank M6 ´ 1.0 4 4 0.4 2.9
Air scoop and radiator panel (lower) M6 ´ 1.0 2 4 0.4 2.9
Front fender mounting M6 ´ 1.0 4 7 0.7 5.1
Rear fender mounting M6 ´ 1.0 4 7 0.7 5.1
Headlight stay (under) and under bracket M6 ´ 1.0 2 7 0.7 5.1
Headlight M6 ´ 1.0 3 7 0.7 5.1
Tail light M6 ´ 1.0 3 4 0.4 2.9
Tail light lead clamp and rear fender M4 ´ 1.59 2 1 0.1 0.7
Coolant reservoir tank M6 ´ 1.0 2 7 0.7 5.1
Sidestand bracket and frame M10 ´ 1.25 2 64 6.4 46
Sidestand mounting M10 ´ 1.25 1 64 6.4 46

2 - 38
SPEC

CABLE ROUTING DIAGRAM
EC240000
CABLE ROUTING DIAGRAM
1
Hose guide
2
Brake hose
3
Regulator
4
Fuel tank breather hose
5
Oil tank breather hose
6
Clamp
7
“ENGINE STOP” button lead
8
Sub wire harness
9
Tail light lead
0
TPS (throttle position sensor) lead
A
Neutral switch lead
B
Oil hose
C
Cylinder head breather hose
D
CDI magneto lead
E
Hose holder
F
Clutch cable
G
Decompression cable
H
Lights switch lead
I
Carburetor breather hose
J
Overflow hose
K
Coolant reservoir tank breather hose

Pass the fuel tank breather
hose behind handlebar, then
insert it into the steering shaft
hole.
õ
Pass the decompression
cable, “ENGINE STOP” but-
ton lead and lights switch lead
under where the oil hose is
attached.
‚
Fasten the CDI magneto lead,
neutral switch lead “ENGINE
STOP” button lead and lights
switch lead to the frame with a
plastic locking tie.
ë
Pass the “ENGINE STOP” but-
ton lead and lights switch lead
along the inner side of the oil
tank breather hose.
ä
Fasten the sub wire harness,
“ENGINE STOP” button lead
and lights switch lead to the
frame in front of the protector
of the sub wire harness with a
plastic locking tie and cut off
the tie end.
ì
Pass the cylinder head
breather hose along the right
side of the oil tank breather
hose.
í
Fasten the sub wire harness
and “ENGINE STOP” button
lead to the frame with a plas-
tic locking tie and cut off the
tie end.
î
Pass the sub wire harness
between the engine brackets.

3 - 2
INSP
ADJ

MAINTENANCE INTERVALS
SHIFT FORK, SHIFT CAM, GUIDE BAR
Inspect
c
Inspect wear
ROTOR NUT
Retighten
cc
MUFFLER
Inspect and retighten
Clean
Replace
cc
c
c
*Whichever comes first
*SPARK ARRESTER
Clean
(Every
six
months)
c
CRANK
Inspect and clean
cc
CARBURETOR
Inspect, adjust and clean
cc
When using a high-pres-
sure washer, make sure
that water does not enter
the accelerator pump.
SPARK PLUG
Inspect and clean
Replace
cc
c
DRIVE CHAIN
Lubricate, slack, alignment
Replace
cc
c
Use chain lube
Chain slack: 40 ~ 50 mm
(1.6 ~ 2.0 in)
COOLING SYSTEM
Check coolant level and leakage
Check radiator cap operation
Replace coolant
Inspect hoses
cc
cc
c
Every two years
OUTSIDE NUTS AND BOLTS
Retighten
cc
Refer to “STARTING AND
BREAK-IN” section in the
CHAPTER 1.
AIR FILTER
Clean and lubricate
Replace
cc
c
Use foam air-filter oil
OIL STRAINER (frame)
Clean
c
FRAME
Clean and inspect
cc
FUEL TANK, COCK
Clean and inspect
cc
BRAKES
Adjust lever position and pedal height
Lubricate pivot point
Check brake disc surface
Check fluid level and leakage
Retighten brake disc bolts, caliper
bolts, master cylinder bolts and union
bolts
Replace pads
Replace brake fluid
c
c
c
c
cc
c
c
c
c
c
c
Every one year ItemAfter
break-inEvery
race
Every
third
or
500 km
(300 mi)Every
fifth
or
1,000 km
(600 mi)
As re-
quiredRemarks


3

3 - 4
INSP
ADJ

PRE-OPERATION INSPECTION AND MAINTENANCE
EC320000
PRE-OPERATION INSPECTION AND MAINTENANCE
Before riding for break-in operation, practice or a race, make sure the machine is in good operating
condition.
Before using this machine, check the following points.
GENERAL INSPECTION AND MAINTENANCE
Item Routine Page
CoolantCheck that coolant is filled up to the radiator filler cap.
Check that the coolant level is correct in the coolant reservoir
tank.
Check the cooling system for leakage.P.3-5 ~ 9
FuelCheck that a fresh gasoline is filled in the fuel tank. Check the
fuel line for leakage.P.1-13
Engine oilCheck that the oil level is correct. Check the crankcase and
frame oil line for leakage.P.3-14 ~ 18
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the
clutch operates smoothly.P.3-10
Throttle grip/HousingCheck that the throttle grip operation and free play are correctly
adjusted. Lubricate the throttle grip and housing, if necessary.P.3-10 ~ 11
Brakes Check the play of front brake and effect of front and rear brake. P.3-26 ~ 32
ChainCheck chain slack and alignment. Check that the chain is lubri-
cated properly.P.3-33 ~ 35
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-42 ~ 44
SteeringCheck that the handlebar can be turned smoothly and have no
excessive play.P.3-44 ~ 45
Front forks and rear shock
absorberCheck that they operate smoothly and there is no oil leakage. P.3-35 ~ 42
Cables (wires)Check that the clutch and throttle cables move smoothly. Check
that they are not caught when the handlebars are turned or
when the front forks travel up and down.—
Muffler Check that the muffler is tightly mounted and has no cracks. —
Sprocket Check that the driven sprocket tightening bolt is not loose. P.3-33
Lubrication Check for smooth operation. Lubricate if necessary. P.3-46
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-18
Lead connectorsCheck that the CDI magneto, CDI unit, and ignition coil are con-
nected tightly.P.1-6
SettingsIs the machine set suitably for the condition of the racing course
and weather or by taking into account the results of test runs
before racing? Are inspection and maintenance completely
done?P.7-1 ~ 22

3 - 6
INSP
ADJ

COOLANT REPLACEMENT
CAUTION:

Take care so that coolant does not splash
on painted surfaces. If it splashes, wash it
away with water.
1. Place a container under the engine.
2. Remove:
l
Seat
Refer to ”SEAT FUEL TANK AND SIDE
COVERS” section in the CHAPTER 4.
3. Disconnect:
l
Coolant reservoir hose
1

Drain the coolant completely.
4. Connect:
l
Coolant reservoir hose
LOWFULLCOOLANT1

5. Remove:
l
Engine guard
1

l
Coolant drain bolt
2

6. Remove:
l
Radiator cap
Drain the coolant completely.
7. Clean:
l
Cooling system
Thoroughly flush the cooling system
with clean tap water.
8. Install:
l
Copper washer
l
Coolant drain bolt
l
Engine guard
l
Bolt [engine guard (front)]
l
Bolt [engine guard (rear)]
New
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
T R..34 Nm (3.4 m · kg, 24 ft · lb)
T R..23 Nm (2.3 m · kg, 17 ft · lb)

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INSP
ADJ
PILOT SCREW ADJUSTMENT
10. Install:
lOil filler plug
11. Inspect:
lEngine (for oil leaks)
lOil level
Refer to “ENGINE OIL LEVEL INSPEC-
TION”.
12. Check:
lOil pressure
PILOT SCREW ADJUSTMENT
1. Adjust:
lPilot screw 1
* Except for USAChecking steps:
lSlightly loosen the oil gallery bolt 1.
lStart the engine and keep it idling until oil
starts to seep from the oil gallery bolt. If no
oil comes out after one minute, turn the
engine off so it will not seize.
lCheck oil passages, oil filter and oil pump
for damage or leakage.
lStart the engine after solving the prob-
lem(s) and recheck the oil pressure.
lTighten the oil gallery bolt to specification.
T R..
Oil gallery bolt:
18 Nm (1.8 m • kg, 13 ft • lb)
Adjusting steps:
NOTE:
To optimize the fuel flow at a smaller throttle
opening, each machine’s pilot screw has
been individually set at the factory. Before
adjusting the pilot screw, turn it in fully and
count the number of turns. Record this num-
ber as the factory-set number of turns out.
lTurn in the pilot screw until it is lightly
seated.
lTurn out the pilot screw by the factory-set
number of turns.
Pilot screw:
WR426F: 1-5/8 turns out
* 7/8 turns out
WR400F: 1-1/2 turns out
(example)

3 - 19
INSP
ADJIDLE SPEED ADJUSTMENT/
VALVE CLEARANCE ADJUSTMENT
EC35M021
IDLE SPEED ADJUSTMENT
1. Start the engine and thoroughly warm it
up.
2. Adjust:
lIdle speed
Adjustment steps:
lAdjust the pilot screw.
Refer to “PILOT SCREW ADJUSTMENT”
section.
lTurn the throttle stop screw 1 until the
engine runs at the lowest possible speed.
To increase idle speed ®
Turn the throttle stop screw 1 in a.
To decrease idle speed ®
Turn the throttle stop screw 1 out b.
Engine idling speed:
1,700 ~ 1,900 r/min
VALVE CLEARANCE ADJUSTMENT
NOTE:
lThe valve clearance should be adjusted
when the engine is cool to the touch.
lThe piston must be at Top Dead Center
(T.D.C.) on compression stroke to check or
adjust the valve clearance.
1. Remove:
lSeat
lFuel tank
Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section in the CHAPTER 4.
2. Remove:
lCarburetor
Refer to “CARBURETOR” section in
the CHAPTER 4.
lSpark plug cap
lEngine stay (upper)
lCylinder head cover
Refer to “CAMSHAFTS” section in the
CHAPTER 4.
3. Remove:
lTiming plug 1
lStraight plug 2
lO-ring