2021 YAMAHA YZ85 cylinder

Operation and important ri din g points
6-2
6
the higher gears and check the
full-throttle response. Stop the en-
gine and check the spark plug.
5. After again allowing the engine to cool, restart and run the motorcy-
cle for 5 more minutes. Full throttle
and the higher gears may be used,
but sustained full-throttle opera-
tion should be avoided. Stop the
engine and check the spark plug
again.
6. Allow the engine to cool, remove the cylinder head and cylinder,
and inspect the piston and cylin-
der. Remove any high spots on
the piston with #600-grit wet
sandpaper. Clean all components
and carefully reassemble the cyl-
inder head and cylinder.
7. Drain the break-in oil-fuel mixture from the fuel tank and refill with
the normal oil-fuel mixture. (See
page 4-4.)
8. Start the engine and check its power delivery and throttle re-
sponse throughout all gear rang-
es. Stop the engine and check the
spark plug condition. It should be-
gin to lighten in color.
9. Restart the motorcycle and ride it for about 10 to 15 more minutes.
Stop the engine and check the
spark plug condition. (See page
7-6.)
10. Lastly, thoroughly check the mo- torcycle for loose parts, oil leak-
age and any other problems.
Check all fittings and fasteners
and tighten as necessary.
TIP
Be sure to inspect and make adjust-
ments thoroughly. In particular, check
control cable slack, drive chain slack
and for loose spokes.
Notes on en gine overhauls
If the following parts have been re-
placed, they must be broken in as fol-
lows.  Piston, rings or transmission
gears: 30 minutes of break-in op-
eration at half-throttle or less.
 Cylinder or crankshaft: 60 minutes
of break-in operation is necessary.
TIP
Observe the condition of the engine
carefully during break-in operation.
NOTICE
ECA10271
If any en gine trou ble shoul d occur
d urin g the en gine break-in perio d,
imme diately have a Yamaha dealer
check the vehicle.
UB4B82E0.book Page 2 Wednesday, March 11, 2020 1:10 PM

Periodic maintenance an d a djustment
7-2
7
EAU66354
Perio dic maintenance an d lu brication chart
The following chart is intended as a general guide to maintenance and lubrication.
Bear in mind that such factors as weather, terrain, geographical location, and in-
dividual usage will alter the required maintenance and lubrication intervals. If you
are in doubt as to what intervals to follow in maintaining and lubricating your mo-
torcycle, consult your Yamaha dealer.
TIP
Items marked with an asterisk should be performed by a Yamaha dealer as they
require special tools, data and technical skills.
NO. ITEM ROUTINEAfter
break-in
Everyrace
Every
third race
Every
fifth race
As
required
1 *Piston Check piston for carbon deposits and
cracks or damage. Clean.
Replace.

2 *
Piston rings Check piston ring end gap and rings
for damage.
Replace.
3 *
Piston pin and small
end bearing Check piston pin and small end
bearing for damage.
Replace.
4 *
Cylinder head Check cylinder head for carbon
deposits.
 Clean.
Check cylinder head gasket fordamage.
 Tighten cylinder head nuts ifnecessary.
Replace cylinder head gasket.

5 *
Cylinder
6*YPVS Check cylinder for score marks or
wear.


 Clean.
Replace.
Check YPVS for carbon deposits andcracks or damage.
Clean.

UB4B82E0.book Page 2 Wednesday, March 11, 2020 1:10 PM

Periodic maintenance an d a djustment
7-4
7
23 *Front fork Check operation and for oil leakage.
Adjust if necessary.
 Clean dust seal and lubricate with
lithium-soap-based grease.
Replace fork oil.
 Replace oil seals.
NO. ITEM ROUTINE
After
break-in
Everyrace
Every
third race
Every
fifth race
As
required
Check coolant level and for leakage.
17 *
Cooling system Check hoses for cracks or damage. Check radiator cap spring operation. Change coolant.
Every 2 years
Every year Check all chassis fitting and fasteners.
18
*Chassis fasteners
Correct or tighten if necessary.
19Air filter element Clean. Replace.
20 *Frame Clean and check for damage.

21
*Fuel line Clean and check for leakage.
22 *
Brakes Adjust lever position and pedal height.
Lubricate pivot points.
Check brake disk surface.
Check fluid level and for leakage.
Tighten brake disk bolts, caliper bolts,
master cylinder bolts and union bolts.
Replace brake pads.
 Replace brake fluid.
UB4B82E0.book Page 4 Wednesday, March 11, 2020 1:10 PM

Periodic maintenance an d a djustment
7-21
7
EAU51721
Chan gin g the brake flui d
Have a Yamaha dealer change the
brake fluid at the intervals specified in
the periodic maintenance and lubrica-
tion chart. In addition, have the oil seals
of the master cylinders and calipers as
well as the brake hoses replaced at the
intervals listed below or whenever they
are damaged or leaking.
 Oil seals: Replace every two
years.
 Brake hoses: Replace every four
years.
EAU22762
Drive chain slack
The drive chain slack should be
checked before each ride and adjusted
if necessary.
EAU84400To check the d rive chain slack
1. Place the motorcycle on a suitable stand. (See page 7-28.)
2. Confirm the rear wheel is off the ground and the rear shock ab-
sorber is fully extended.
3. Shift the transmission into neutral.
4. Pull up the drive chain until the chain is taut, and then measure
distance A between the top of the
swingarm and the bottom of the
chain as shown.
5. If the drive chain slack is incorrect, adjust it as follows. NOTICE: Im-
proper drive chain slack will
overload the engine as well as
other vital parts of the motorcy-
cle an d can lead to chain slip-
pa ge or breakag e. To prevent
1. Distance A
Distance A:
58.0–68.0 mm (2.28–2.68 in) (YZ85,
YZ85M)
65.0–75.0 mm (2.56–2.95 in)
(YZ85LW, YZ85LWM)
1
UB4B82E0.book Page 21 Wednesday, March 11, 2020 1:10 PM

Motorcycle care and stora ge
8-4
8
EAU86460
Stora ge
Always store the vehicle in a cool, dry
place. If necessary, protect it against
dust with a porous cover. Be sure the
engine and the exhaust system are
cool before covering the vehicle. If the
vehicle often sits for weeks at a time
between uses, the use of a quality fuel
stabilizer is recommended after each
fill-up.
NOTICE
ECA21170
 Storin g the vehicle in a poorly
ventilate d room or coverin g it
with a tarp, while it is still wet,
will allow water an d humi dity to
seep in an d cause rust.
 To prevent corrosion, avoi d
d amp cellars, sta bles ( because
of the presence of ammonia)
an d areas where stron g chemi-
cals are store d.
Lon g term stora ge
Before storing the vehicle long term (60
days or more): 1. Make all necessary repairs and perform any outstanding mainte-
nance.
2. Follow all instructions in the Care Section of this chapter.
3. Fill up the fuel tank and add fuel stabilizer according to product in-
structions.
4. Run the engine for 5 minutes to distribute treated fuel through the
fuel system.
5. For vehicles with a fuel cock: Turn the fuel cock lever to the off posi-
tion. 6. For vehicles with a carburetor: To
prevent fuel deposits from build-
ing up, drain the fuel in the carbu-
retor float chamber into a clean
container. Retighten the drain bolt
and pour the fuel back into the fuel
tank.
7. Use a quality engine fogging oil according to product instructions.
If engine fogging oil is not avail-
able, perform the following steps
for each cylinder:a. Remove the spark plug cap and spark plug.
b. Pour a teaspoonful of engine oil into the spark plug bore.
c. Install the spark plug cap onto the spark plug, and then place
the spark plug on the cylinder
head so that the electrodes are
grounded. (This will limit spark-
ing during the next step.)
d. Turn the engine over several times with the starter or kick-
starter. (This will coat the cylin-
der wall with oil.) WARNING!
To prevent d amage or injury
from sparkin g, make sure to
g roun d the spark plu g elec-
tro des while turnin g the en-
g ine over.
[EWA10952]
e. Remove the spark plug cap
from the spark plug, and then
install the spark plug and the
spark plug cap.
8. Lubricate all control cables, piv- ots, levers and pedals, as well as
the sidestand and centerstand (if
equipped).
9. Check and correct the tire air pressure, and then lift the vehicle
so that all wheels are off the
UB4B82E0.book Page 4 Wednesday, March 11, 2020 1:10 PM

Specifications
9-1
9
Dimensions:
Overall length:1820 mm (71.7 in) (YZ85, YZ85M)
1895 mm (74.6 in) (YZ85LW, YZ85LWM)
Overall width: 760 mm (29.9 in)
Overall height:
1145 mm (45.1 in) (YZ85, YZ85M)
1175 mm (46.3 in) (YZ85LW, YZ85LWM)
Seat height:
840 mm (33.1 in) (YZ85, YZ85M)
870 mm (34.3 in) (YZ85LW, YZ85LWM)
Wheelbase:
1255 mm (49.4 in) (YZ85, YZ85M)
1285 mm (50.6 in) (YZ85LW, YZ85LWM)
Ground clearance: 330 mm (12.99 in) (YZ85, YZ85M)
360 mm (14.17 in) (YZ85LW, YZ85LWM)
Wei ght:
Curb weight:
73 kg (161 lb) (YZ85, YZ85M)
75 kg (165 lb) (YZ85LW, YZ85LWM)
Engine:
Combustion cycle:
2-stroke
Cooling system: Liquid cooled
Number of cylinders:
Single cylinder
Displacement: 85 cm³
Bore × stroke:
47.5 × 47.8 mm (1.87 × 1.88 in)
Starting system:
Kickstarter
Engine oil:
Engine oil:
YAMALUBE 2R
Recommended brand:
Transmission oil:
Type:
Motor oil SAE 10W-30 type SE or higher or
Gear oil SAE 85W GL-3
Quantity:
0.50 L (0.53 US qt, 0.44 Imp.qt)
Coolant quantity:
Radiator (including all routes): 0.55 L (0.58 US qt, 0.48 Imp.qt)
Fuel:
Recommended fuel:Unleaded gasoline (E10 acceptable)
Octane number (RON): 98
Fuel tank capacity:
5.0 L (1.3 US gal, 1.1 Imp.gal)
Car buretor:
Type × quantity:
PWK28 × 1
Drivetrain:
Gear ratio:
1st:
2.455 (27/11)
2nd:
1.882 (32/17)
3rd: 1.529 (26/17)
4th: 1.294 (22/17)
5th:
1.130 (26/23)
6th: 1.000 (25/25)
Front tire:
Type:
With tube
Size: 70/100-17 40M (YZ85, YZ85M)
70/100-19 42M (YZ85LW, YZ85LWM)
Manufacturer/model: DUNLOP/MX3SF
Rear tire:
Type:
With tube
Size: 90/100-14 49M (YZ85, YZ85M)
90/100-16 52M (YZ85LW, YZ85LWM)
Manufacturer/model: DUNLOP/MX3S
Front brake:
Type:
Hydraulic single disc brake
Rear brake:
Type:
Hydraulic single disc brake
UB4B82E0.book Page 1 Wednesday, March 11, 2020 1:10 PM