Mounting Instructions
Öhlins front fork kit FG KT 491 for KTM SX 125 2004
© Öhlins Racing AB. All rights reserved. Any reprinting or unauthorized use without the
written permission of Öhlins Racing AB is prohibited. Printed in Sweden.
Öhlins front fork MX
CAUTION!
The front fork springs are delivered separately and
must be installed before the front fork is mounted
to the bike. See page 4.
Your Öhlins front fork MX 2004 is an upside down
type front fork featuring the following adjusters.
Compression damping adjuster
The high and low speed compression adjuster is
located at the bottom of the fork leg.
High speed adjustments are made by turning
the nut. Use a 12 mm socket. Low speed adjust-
ments are made by turning the screw. Use a slot
screw driver.
Rebound damping adjuster
Adjustments are made at the top of the fork leg.
Use a slot screw driver.
Spring pre-load adjuster
Adjustments are made by turning the nut at the top
of the fork leg. Clockwise for harder adjustment,
counter clockwise too release the pre-load.
Use a 17 mm key.
NOTE!
When delivered the Öhlins front fork is dialed to
recommended settings for the specific brand and
make of the motorcycle. If you have changed the
settings, check like this:
The adjusters have a normal right hand tread. Turn
the damping adjusters clockwise to fully closed (pos.
zero [0]). Turn counter clockwise to open and count
the clicks until you reach the recommended number
of clicks. See Setup data on page 8.
CAUTION!
Do not use too much force, delicate sealing sur-
faces can be damaged.
High speed
compression
adjustment
Low speed
compression
adjustment
Rebound damping
adjuster
Spring pre-load
adjuster
Checking sag and ride height
Front suspension
F1. Bike on a stand with the
suspension fully extended = ............
F2. Bike on the ground without rider = ............
F3. Bike on the ground with rider = ............
Free sag
F1 - F2 = ............
Recommended: 30±5 mm
Ride height
F1 - F3 = ............
Recommended: 80±5 mm
Rear suspension
R1.Bike on a stand with the
suspension fully extended = ............
R2.Bike on the ground without rider = ........... .
R3.Bike on the ground with rider = ............
Free sag
R1 - R2 = ............
Recommended: 30±5 mm
Ride height
R1 - R3 = ............
Recommended: MX 100±5 mm
Enduro 30% of the total stroke
NOTE!
If ride height is higher than recommended,
softer spring/springs must be used.
If ride height is lower than recommended,
harder spring/springs must be used.
Contact your Öhlins dealer for advice.
Öhlins Racing AB, Box 722, S-194 27 Upplands Väsby, Sweden.
Phone +46 8 590 025 00. Fax +46 8 590 025 80.
www.ohlins.com
Part No. FG YA 491. Issued 03 12 17
Setup data
Lenght 933 mm
Stroke 300 mm
Rebound adjuster 14 clicks
Low speed comp. adjuster 14 clicks
High speed comp. adjuster 1 turn
Spring preload 4 mm
Front fork oil level 105 mm
Front fork position 4 mm
Fork position is
measured from
the top of the fork
leg, to the top
surface of the
triple clamp.
x mm
Oil level
Oil level is
measured from
the top of the
outer leg, with the
top nut off, the
fork fully
compressed and
no spring
installed.
Bike on a stand.
F1
R1
Bike on the ground.
F2
R2
Bike with rider on.
F3
R3
Öhlins products are subject to continual improve-
ment and development. Consequently, although
these instructions include the most up-to-date
information available at the time of printing, there
may be minor differences between your suspen-
sion and this manual. Please consult your Öhlins
dealer if you have any questions with regard to
the contents of the manual.
NOTE!
During storage and transportation, espe-
cially at high ambient temperature, the oil
and grease used for assembling may run out
inside the packing and damage the
expanded polystyrene packing material. This
is not unusual and is in no way detrimental
to thefront fork.
Kit contents
Before installing the suspension components,
please check the contents of the kit, listed on
the front page of this instruction. If anything is
missing, contact your Öhlins dealer.
Description Part No. Pcs.
Front fork type FG KT 491
Spring (4.1 N/mm) 02428-41 2
Spring (4.3 N/mm)*
Spring (4.5 N/mm) 02428-45 2
Spring HSC (40 N/mm) 04107-04 2
Pre-load tube 02437-20 2
Fork leg cover 02309-80 1 pair
Bolts for cover, M6x12 02314-01 6
Sticker Öhlins 02332-05 2
Sticker Öhlins 00197-01 2
Owners Manual 1
* Use a 4.1 N/mm spring in one leg and
a 4.5 N/mm in the other.
Before installation
Öhlins Racing AB can not be held responsible for
any damage whatsoever to suspension components
or vehicle, or injury to persons, if the instructions for
fitting and maintenance are not followed exactly.
Similarly, the warranty will become null and void if
the instructions are not adhered to.
WARNING!
1. Installing suspension components, that is
not approved by the vehicle manufacturer,
may affect the stability of your vehicle. Öhlins
Racing AB cannot be held responsible for
any personal injury or damage whatsoever
that may occur after fitting the suspension
components. Contact an Öhlins dealer or
other qualified person for advice.
2. Please study and make certain that you
fully understand all the mounting instructions
and the owners manuals before handling this
suspension components kit. If you have any
questions regarding proper installation
procedures, contact an Öhlins dealer or other
qualified person.
3. The vehicle service manual must be
referred to when installing the Öhlins
suspension components
Safety signals
Important information concerning safety is
distinguished in this manual by the
following notations:
The Safety alert symbol means:
Caution! Your safety is involved.
WARNING!
Failure to follow warning instructions
could result in severe or fatal injury
to anyone working with, inspecting or
using the suspension, or to bystanders.
CAUTION!
Caution indicates that special
precautions must be taken to avoid
damage to the suspension.
NOTE!
This indicates information that is of
importance with regard to procedures.
Notes
WARNING!
1. It’s advisable to have an Öhlins dealer or other
qualified person to fit your front fork.
2. Instructions in the motorcycle workshop manual
are to be followed when removing the front fork.
3. When working on the motorcycle it must be
securely supported to prevent it from falling over.
Mounting Instructions
1
Put the bike on a stand so the front wheel has
ground clearance. Make sure it’s steadily positioned
and will not fall over.
2
Remove the front wheel, protecting covers and
the brake caliper. Let the caliper stay fitted to the
brake hose.
3
Remove the original fork legs and fit the Öhlins
fork legs to the triple clamps.
CAUTION!
Do not overtighten the clamps. There is a risk of
deforming the fork leg tubes. See page 5 for
correct torques.
NOTE!
The front fork legs must be aligned be-
fore the front wheel axle is tightened.
2
3
2
5
Upper triple clamp
Lower triple clamp
Front leg cover
Brake
caliper
Caliper
protection
cover
Front fork leg
Front wheel
6
Tighten the wheel axle and refit the removed pro-
tecting covers. Fit the Öhlins front leg covers.
NOTE!
Make sure that all bolts are tightened to the correct
torque and that nothing restrains the front fork when
the suspension is been fully compressed. See the
motorcycles workshop manual.
7
Continue your work with adjustments, see Öhlins
Owners Manual.
NOTE!
Before you continue, make sure that the front
springs are installed. If they are not, proceed with
the instructions at page 4 – Installing springs.
4
Put the wheel back in position. Reassemble the
brake and fit the hose holder.
NOTE!
Do not tighten the front wheel axle before the
front legs are aligned. (5)
5
Let the motorcycle stand on the ground and com-
press the front suspension as hard as possible a
couple of times. This will align the fork legs.
NOTE!
Another way to align the front legs is to rotate
the front wheel as fast as possible and bring it to
a fast stop by braking.
Base valve housing
Change of high speed
compression spring
1
Turn the fork leg upside down and fasten the fork
bottom in a vise with soft jaws
2
Remove the compression (base) valve. Use a 23
mm socket.
3
Fasten the valve in a vise with soft jaws.
4
Use tool (1863-01) or a pair of pointed pliers to
loosen the poppet valve seat and remove it to-
gether with the poppet valve and the spring.
5
Install the new spring, refit the poppet valve and
the poppet valve seat. Tighten to a torque of 5 Nm.
6
Refit the valve unit to the fork bottom as de-
scribed above. Tighten to a torque of 65 Nm.
Tool 1863-01
Poppet valve seat
Poppet valve
Spring (4107-03/04)
Front fork leg
2-way base valve
Shims
Installing springs
1
Unscrew the top cap, using top cap tool 1761-02.
If tool 1761-02 is not at hand, use a 17 mm
wrench and unscrew the spring pre-load adjuster.
When the adjuster locks in fully open position,
the top nut will turn with the adjuster nut.
2
NOTE!
Closing the compression and the rebound valves
will keep the damper rod extended, making it
easier to install the new spring.
Pull out the damper rod as far as possible.
Close the compression and the rebound valve
(clockwise).
Tool 1761-02
Top cap
Fork leg
Slot
screwdriver
Guide sleeve
3
Install the the correct spring. Two pairs of springs
are provided – spring ratio 4.1 N/mm and 4.5 N/
mm, respectively.
NOTE!
A spring ratio of 4.3 N/mm is obtained if a 4.1 N/mm
spring is used in one leg and a 4.5 N/mm spring in
the other leg.
4
Reinstall the spring support, the pre-load tube
and the top nut.
Spring
Top cap
Pre-load tube
Spring support
4
3
1
2
17 mm
wrench
Top cap
Fork leg
5
Install the fork top cap. Tighten (30 Nm) the top
cap and the lock nut against each other, use a
17 mm and 24 mm wrench.
Adjust the compression and the rebound valves
according to specification card.
17 mm
wrench
24 mm
wrench
5
CAUTION!
Do not overtighten the clamps. There is a risk of
deforming the fork leg tubes. See the motorcycle’s
Workshop manual for correct torques.
7
Fit the legs on the motorcycle.
Tightening torques:
Upper tripple clamp: 20 Nm
Lower triple clamp: 10 Nm
6
Refit the top cap and tighten. Use top cap tool
1761-02.
The top cap should not be tightened hard, only
turned in position by hand.
Tool
1761-02
6
-
1
-
2
-
3
-
4
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