ATK 250LQ 1995 User manual

Thank You...
... for purchasing an American-made
ATK motorcycle. ATK is committed to
building the highest-quality, best-han
dling off-road motorcycles in the world.
Prime examples of that commitment
are readily visible on every ATK
model: Beautiful components such as
machined-from-billet aluminum hubs
and triple clamps, Protaper handle
bars, 4130 chrome-moly steel frames
and swingarms, premium-quality O-
Ring drive chains, Travelcade seat-
foam and covers, and maintenance-
free rear suspension systems are fea
tures you won't find on any competing
brand of off-road motorcycle.
Using beautiful, high-quality parts pro
vides more than pleasure for the eyes,
though. They insure that, given mini
mal care and maintenance, an ATK
motorcycle will provide years of trou
ble-free off-road pleasure.
Thus, we urge you to read this manu
al-it's easy to digest-and to visit your
ATK dealer if you have any bike prob
lems, need advice or replacement
parts or accessories.
Thanks again for buying an ATK.
Have fun.
Sincerely,
Michael L. Tullis
C.E.O., ATK America.
ATK1995Owner'sManual

CONTENTS
Specifications
Adjustments
Starting Procedures
Suspension
Brakes
3
4
8
9
10
Carburetion 11
Maintenance 13
ATK1995Owner'sManual

INTRODUCTION
Congratulations on your purchase
of America's finest off road motor
cycle: The ATK.
This manual explains operation,
inspection, basic maintenance and
tuning of your machine. If you have
any questions about this manual or
your machine, please contact your
localATK dealer.
«* WARNING
Please read this manual carefully and
completely before operating this machine.
Do not attempt to operate this machine
until you have attained a satisfactory
knowledge of its controls and operating
features and until you have been trained in
safe and proper riding techniques. Regular
inspections and careful maintenance,
along with good riding skills, will ensure
that you safely enjoy the capabilites and
the reliability of this machine.
-* IMPORTANT NOTICE
This machine is designed strictly for com
petition use, on a closed course. It is illegal
for this machine to be operated on any
public street, road, or highway. Off road
use on public lands may also be illegal.
Please check local regulations before rid
ing.
^SAFETYINFORMATION
1. This machine is to be operated by an
experienced rider only. Do not attempt to
operate this machine at maximum power
until you are totally familiar with its charac
teristics.
2. This machine is designed to be ridden
by the operator only. Do not carry passen
gers on this machine.
3.Always wear protective apparel. When
operating this machine, always wear an
approved helmet with goggles or a face
shield.Also wear heavy boots, gloves, and
protective clothing.Always wear proper fit
ting clothing that will not be caught in any
of the moving parts or controls of the
machine.
4.Always maintain your machine in proper
working order. For safety and reliability,
the machine must be properly maintained.
Alway perform the pre-operation checks
indicated in this manual. Correcting a
mechanical problem before you ride may
prevent an accident.
5. Gasoline is highly flammable and can
cause injury or death.Always turn off the
engine while refueling. Take care to not
spill any gasoline on the engine or exhaust
system. Never refuel in the vicinity of an
open flame, or while smoking. If you
should swallow gasoline, inhale excess
gasoline vapors, or allow gasoline to get
into your eyes, contact a doctor immedi
ately.
6. Only operate the machine in an area
with adequate ventilation. Exhaust fumes
are poisonous. These fumes contain car
bon monoxide, which by itself is odorless
and colorless. Carbon monoxide is a dan
gerous gas which can cause unconscious
ness or can be lethal.
7. Park the machine carefully.
8. Properly secure the machine before
transporting it. When transporting the
machine in another vehicle, always be
sure it is properly secured in an upright
position and that the fuel cock is in the 'off'
position. Otherwise, fuel may leak out of
the carburetor or fuel tank. For transport
ing we recommend The Bike Shoe, avail
able from yourATK dealer.
ATK1995Owner'sManual

SPECIFICATIONS Standard shock spring5.6Kg/mm
Optionalshockspring5.2;5.4;5.8kg/mm
Model
Displacement
Engine type
Bore and stroke
Compression ratio
Carburetion
Ignition
Sparkplug
Transmission
Starting system
Fuel capacity
Fuel requirements
Wheelbase
Rake/trail
Seat height
Ground clearance
Footpeg height
Footpeg to seat top
Swingarmlength
Front tire
Reartire
Tire pressure
Front wheel travel
External adjustments
Standard forkspring rate
Optionalforksprings
Rearwheeltravel
External adjustments
ATK250LQ/260LQ
250/251CC
Liquid-cooled two-stroke Single
67.5X69.8 /67.75X69.8mm
7.04:1
38mmMikuniTMS
SEM12v160w
NGKB8ES
wide-ratio 6-speed
kick
3.1 gallons
SO+octane
58.5 inches
27.1/4.6 inches
37.2 inches
13.5 inches
16.2 inches
20.5 inches
22.5 inches
90/90-21
120/80-18
12-18psi front and rear
11.8 inches
compression&rebounddamping
0.42 kg/mm
0.38; 0.40; 0.44 kg/mm
13.6 inches
compression&rebounddamping,
spring preload
Front brake
Rearbrake
Final drive ratio
Drive chain
Internal gearratios:
LQ250/LQ260
Primarydrive
1st
2nd
3rd
4th
5th
Nissin dual piston, 9.0-inch
stainless-steel rotor
Nissin dual piston, 8.7 inch
stainless-steel rotor
15-48
DID.520VSO-ring
Coolent Capacity, total
Coolent mixture
Standard thermostat
Optional thermostats
1.25 quarts
50/50 water/antifreeze
113 degree
136; 158 degree
25/69 2.760
10/30 3.000
14/29 2.071
14/23 1.643
15/21 1.400
18/22 1.222
19/21 1.105
Weight, wet no fuel: 230 pounds
Recommended trans- 10/40winter/
mission oil 20/50 summer
Transmissionoilcapacity600cc;6/10quart
Fuel/oil mixing ratio 62:1
Brake fluid Bel-Ray DOT 5
ATK1995Owner'sManual

ADJUSTMENTS
Rear suspension:
Rear suspension sag is preset at the
factory for a rider of approximately 170
pounds. But it should be rechecked for
optimum performance. To set the sag,
place the bike on a stand or box that
lifts the rear wheel clear of the ground,
then measure the distance from the
center of the rear axle to the center of
the seat-mounting bolt and record that
number. Next, put the motorcycle on
the ground and bounce on it a few
times to loosen up the shock and
swingarm pivots. With the rider sitting
on the bike in his normal riding posi
tion, one foot on the ground for bal
ance, have an assistant remeasure
the distance from rear axle bolt center
to the seat mount bolt and record that
number. The difference in measure
ments should be exactly 3.75 inches
(95mm).
If adjustment is needed, loosen the
shock-spring's locking ring then rotate
the shock spring by hand to increase
its preload. Lessen the preload if more
sag is needed. After rechecking the
sag measurement, tighten the locking
ring firmly using a spanner wrench or
drift punch and hammer.
Shock compression damping:
Compression damping controls the
speed at which the shock compress
es. The compression-adjuster knob is
located on the top of the shock's
reservoir. Moving the knob to a higher
number increases the shock's com
pression resistance and slows the
shock's rate of compression.
Choosing a lower number reduces
resistance to compression and pro
vides a softer ride.
ATK 1995 Owner's Manual

Shock rebound damping: Fork compression damping: Fork rebound damping:
Rebound damping controls the speed
at which the shock returns to its
extended length after being com
pressed. The rebound-adjuster knob is
located below the shock spring, just
above the shock's lower mounting
bolt. A higher number increases
damping resistance and slows the
shock's return after being com
pressed. A lower number decreases
resistance and lets the shock return
faster.
The compression damping adjuster for
the left fork leg controls damping
throughout the fork's travel. Setting
the adjuster to #3 or #4 will provide
smooth, comfortable fork damping.
An identical adjuster of the right fork
leg only effects damping during the
last 3-inches of fork travel. Adjusting
the right knob to a higher number-6,7
or 8-prevents "bottoming" in G-outs.
The fork's rebound damping is adjust
ed via a plastic knob on top of each
fork leg. Turning the thumb screw
adjuster clockwise increases resis
tance and slows the fork's rebound
speed after being compressed.
Turning the knob counter clockwise
reduces resistance and lets the fork
return to full extension quicker.
Top View Top View
S l o w e r F a s t e r
Fork air bleed:
A small screw located on the top of
each fork cap, next to the rebound
damper adjustment, relieves built-up
air pressure in the fork. A small flat-
blade screwdriver is required.
ATK 1995 Owners Manual

Drive chain adjustment:
The drive chain's adjustment should
be checked after each ride. With the
bike on a stand, push the bottom of
the chain up towards the lower end of
the chain rub pad. The chain should
become tight when approximately 1/32
inch away from the rub pad. If adjust
ment is required, loosen the rear axle
nut and adjust the chain tension by
turning the axle-adjuster screws. After
adjustment, retighten the adjuster
screw locknuts and the axle firmly.
Chain alignment is also very important
to long chain and sprocket life. While
on a stand, place a screwdriver shaft
between the upper part of the chain
and the rear sprocket, then turn the
rear tire slowly rearward until the top
of the chain becomes taut. Sight down
the top of the chain. It should appear
straight. If it looks curved, make the
necessary corrections using the
adjuster screws and recheck the
adjustment and axle nut tightness.
Clutch lever:
The clutch lever should be adjusted to
provide 1/4 inch of freeplay at its ball-
end.
Front brake lever:
The front brake level is provided with
an adjuster on its front side that allows
ATK 1995 Owner's Manual

adjustment of the brake's engagement
point. It should be adjusted to the
rider's preference.
Throttle:
The throttle should have a small
amount of freeplay in it. The adjust
ment is located under the rubber cover
between the throttle assembly and
throttle cable.
Rear brake pedal:
The rear brake pedal can be adjusted
by loosening the locknut on the top of
the clevis and then turning the master
cylinder push shaft in or out. After
adjusting, be sure the clevis locknut is
retightened and there is a slight
amount of freeplay in the brake pedal
prior to the push shaft being moved.
Handlebar adjustment:
The Protaper handlebar can be adjust
ed for height and reach. To lower the
handlebar, loosen the four handlebar
clamp bolts, then rotate the bar reward
to lower its height and decrease the
reach. Rotate the bar forward to raise
its height and increase its reach. A
scale printed on the top-center section
of the handlebar provides a reference
for adjustment. After adjusting the
handlebar position, retighten the han
dlebar clamps, starting with the front
bolts followed by the rear bolts.
ATK 1995 Owner's Manual

STARTING PROCEDURES Cold engine:
1) Turn the fuel petcocks to ON.
2) Pull the choke knob up until it stops.
Fuel petcock:
A fuel petcock is located on each side
of the fuel tank. Both petcocks should
be turned to their ON positions (the
petcock levers pointing down) before
operating the motorcycle. Warm engine:
1) Kick the engine briskly with the
throttle opened about 1/8 to 1/4 turn.
3) Kick the engine over briskly with the
throttle closed. After the engine warms
to operating temperature, push the
choke down until it stops.
ATK 1995 Owner's Manual

Engine Stop: SUSPENSION Setting the fork oil level:
1) Push the black kill button on the left
side of the handlebar. Fork oil:
Your new ATK's fork is supplied with
5-weight suspension fluid. 7.5-weight
fluid may be substituted if a firmer ride
is desired. Use only a high-grade sus
pension fluid such as Bel-Ray HVI or
Spectro.
Fork oil level:
Minimum oil level
Maximumoil level
Stock oil level
6.70 inches(170mm)
4.72 inches(120mm)
5.10 inches(130mm)
Effects of oil level:
Raising the fork oil level increases the
fork's resistance to bottoming and
generally makes the suspension feel
stiffer during the last half of its travel.
Lowering the oil level softens the last
half of the travel.
The fork legs must be removed from
the motorcycle to accurately set the oil
level. Prior to fork removal, the forks
caps should be loosened (after loos
ening the top clamp's pinch bolts).
1) Remove the fork legs and one fork
cap.
2) Push the outer tube down a couple
of inches and remove the spring-
retainer clips and the spring preload
spacers.
3) Slowly remove the fork spring from
the fork.
4) Push the damper cartridge and
outer tube to the bottom of their travel,
then raise the outer tube's top edge
flush with the top of the damper car
tridge top.
5) Insert a narrow, steel rule into the
fork between the damper cartridge
and the wall of the outer tube, stop
ping at the 8-inch mark on the rule.
6) Carefully remove the rule and note
ATK1995Owner'sManual

the oil height on it. Subtracting the oil
mark number from 8 gives the oil
level.
Outer tube level with top
of cartridge
Oil level
Outer fork tube —■
Fork fully compressed ,
Cartridge
8in.
2in.
Fork-spring preload:
Fork-spring preload refers to the dis
tance the spring is compressed when
it is installed in the fork with the fork
fully extended.
Effect of spring preload:
Spring preload effects the motorcy
cle's ride height. Increasing the spring
preload raises the ride height of the
bike and makes the fork feel slightly
stiffer during the initial part of its
movement.Generally, a lower fork-
spring preload is advisable.
The recommended fork-spring preload
is10 mm.
Setting the fork-spring preload:
1) Follow steps one and two under
Setting the fork-oil level.
2) Holding the damper cartridge fully
extended, measure the distance from
Spring clip
^-groove
Cartridge fully extended
Spring preload setting
10 mm
the bottom of its spring-clip groove to
the top of the fork spring and record
that number.
3)Add the amount of spring preload
desired to the number derived in (2),
(above) to determine the length of the
preload spacer.
/Spring retainer clips
Plastic spacers
Steel washer
BRAKES
Nissin hydraulic brake components
are used on your newATK. The dual-
piston front and rear calipers are
exactly the same, as are their brake
pads. Using a dual-piston caliper on
the rear wheel offers several advan
tages: brake pad life is greatly
increased; stopping power is greater;
and overheating, even at high-speeds
ATK1995Owner'sManual 10

and during severe use in tight woods,
is reduced.
Brake fluid:
Your new ATK's brake system is filled
with premium Bel-Ray DOT 5 fluid.
DO NOT mix with another brand or
rating of brake fluid. If another brand
or rating is preferred, completely drain
and flush the brake system first.
Brake pads:
Replace the brake pads when the fric
tion pad material is worn to 1/8 inch in
thickness. The front and rear brake
calipers use the same brake pads.
CARBURETION
Type Mikuni TMS
Size 38mm
Main jet 310-330
Needle 6DGY4-59 or
6DGY4-58
Needle clip position 3
Slide G
Bleed screw adjustment 1.5 turns
Adjusting the carburetion:
Your new ATK's carburetion is set at
our Utah factory which has an eleva
tion of around 4,000 feet. To obtain
optimum performance in your riding
area, we suggest that an hour or so be
set aside to fine-tune the carburetor
for your elevation and weather condi
tions.
// ATK 1995 Owner's Manual

Main jet: Air bleed screw: Needle:
When fine-tuning the carburetor start
with the main jet. If the engine sounds
rich or lean under full throttle condi
tions, change the main jet size. The
main jet is located under the float
bowl. It can be reached after float bowl
nut removal which requires a 17mm
boxend wrench. Use a jet wrench to
remove the main jet and then replace
it with a smaller numbered jet if the
bike is running rich, a larger one if it is
running lean.
The air-bleed screw should be adjust
ed for a smooth idle speed. Turning
the screw clockwise reduces the
amount of air-bleed, counter clockwise
increases the amount of air entering
the engine at idle speed. Slowly move
the screw a half turn clockwise and
note the engine's idle speed, then
return it to 1.5 turns and then rotate it
counter clockwise a half turn, noting
the engine speed. If the engine gained
speed in one direction return the
adjuster to that position.
The needle is the long, thin, tapered
steel part that protrudes out the bot
tom of the throttle slide. It is reached
by removing the carburetor's top.
When the top of the carburetor is
pulled away from the carburetor body,
the throttle-return spring and throttle
slide will be attached to it. The needle
jet and the jet needle (the part that the
needle jet slides up and down in) are
responsible for the engine's operation
between 1/4 throttle and 3/4 throttle. If
Clip position from top
5~2 -^ Leanest
Carburetor needle
Richest
ATK1995Owner'sManual 12

the engine is running rich in this
range, lowering the needle (raising the
C-clip at the needle jet's top) will
reduce the amount of fuel flow.
Lowering the C-clip raises the needle
jet and makes the engine richer in this
power range.
MAINTENANCE
Engine oil:
Summer
Winter
Capacity 250/260
Oil change
Changing the oil:
Spectra 20-50w
Spectra 10-40w
6/10 quart
200 miles
Remove the oil-drain plug from the
lower rear of the clutch cover (under
the shift lever) using a 6mm alien
wrench. Replace the plug after drain
ing is complete. Slowly poor oil into
the filler hole located in the top of the
engine's center cases (to the right of
the carburetor) until the oil sight glass
on the clutch cover is half full (approxi
mately 6/10 of a quart). Replace filler
plug.
Drive chain:
Except for an occasional chain tension
adjustment, little chain care is
required. As long as the chain's O-
rings are in good condition, the lube
trapped inside the chain can not
escape and lube applied to the outside
of the chain can not get into the chain
to lubricate its critical parts. A light
lubricant to the outside of the chain to
keep it from rusting may be desirable,
but not absolutely necessary. The
stock chain used on all ATKs is a pre-
13 ATK 1995 Owner's Manual

mium model and should last a long
time. When the chain reaches a point
where side play is obviously exces
sive, it should be replaced.
Drive sprockets:
ATK rear sprockets, like the drive
chain, are the highest quality available
and should provide long life. When the
sprocket teeth start looking bent, it's
time for a new sprocket. The drive
chain should be inspected closely for
excessive side play at the same time
and replaced if bad. A worn drive
chain can wear out a new rear sprock
et in one ride.
Control cables:
The control cables should be lubricat
ed periodically with cable lube to keep
them working smoothly.
Throttle/control levers:
The throttle should be disassembled,
cleaned in cleaning solvent, then all
moving parts lubricated, including the
holder for the throttle-cable's end. The
clutch and front brake levers should
also be cleaned and lubricated at their
pivot points and where the cable ends
are held. The maintenance schedule
for these parts should be determined
by the amount and severity of the
bike's use.
Rear brake pedal:
The rear brake pedal pivots on two (2)
sealed ball bearings and requires no
maintenance.
ATK 1995 Owner's Manual 14

Brake pads: Air filter:
The brake pad's thickness should be
checked after each ride. The pads
should be replaced when they are 1/8
inch thick. The front and rear brake
pads are identical.
Ignition:
The SEM ignition is preset at 2.05mm
BTDC at the factory and should
require no further adjustment.
The air filter should be cleaned in sol
vent after every ride and re-oiled. To
perform this maintenance, remove the
seat, then loosen the hose clamp on
the back of the carburetor and pull the
air filter from the airbox. Regular
engine oil or special foam air filter oil
may be used to oil the filter. Before
installing the air filter into the airbox,
clean the inside of the airbox and
apply heavy waterproof grease to the
front of the sealing flange on the air fil
ter carrier. Then reinstall the filter,
pushing the sealing flange tightly
against the front of the airbox while
tightening the filter carrier hose clamp
to the back of the carburetor.
15 ATK 1995 Owner's Manual