Basic Suspension Setup For The Weight Of The Driver; Checking The Shock Absorber And Spring; Determining The Static Sag Of The Shock Absorber; Determining The Riding Sag Of The Shock Absorber - KTM 125 SX Owner's Manual

26
for example
76/250
60 65 70
RIDERS WEIGHT INCLUSIVE GEARS IN KILOGRAM
A
B
C
125/200 SX
84/250
80/250
75 80 85 90

Basic suspension setup for the weight of the driver

To achieve maximum handling performance and to prevent the fork, shock
absorber, swing arm and frame from being damaged, the basic setup of the
suspension components must be suitable for your weight. At delivery,
KTM's offroad motorcycles are set to accommodate a driver weighing 70 -
80 kg (wearing full protective clothing). If your weight exceeds or falls short
of this range, you will need to adjust the basic setup for the suspension
components accordingly. Minor deviations in weight can be compensated
by adjusting the spring preload. Different springs must be installed for larger
deviations.

Checking the shock absorber and spring

You can establish whether or not the shock absorber spring is suitable for
your weight by checking the riding sag. The static slag must be correctly
adjusted before the riding sag can be determined.

Determining the static sag of the shock absorber

The static sag should be as close as possible to 35 mm. Deviations of more
than 2 mm can strongly influence the motorcycle's performance.
Procedure:
– Jack up the motorcycle until the rear wheel no longer touches the gro-
und.
– Measure the vertical distance between the rear wheel axle and a fixed
point (e.g. a mark on the side cover) and write it down as dimension A.
– Place the motorcycle on the ground again.
– Ask a helper to hold the motorcycle in vertical position.
– Measure the distance between the rear axle and the fixed point again to
establish dimension B.
– The static sag is the difference between dimensions A and B.
EXAMPLE:
Motorcycle jacked up (dimension A) . . . . . . . . . . . . . . . . . . . . . . . .600 mm
Motorcycle on ground, unloaded (dimension B) . . . . . . . . . . . . . .– 565 mm
Static sag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35 mm
If the static sag is lower, the spring preload of the shock absorber must be
increased, if the static sag is reduced, the spring preload must be higher. See
chapter "Changing the spring preload of the shock absorber."

Determining the riding sag of the shock absorber

– Have a helper hold the motorcycle while you sit on the bike in a normal
seating position (feet on the footrests) wearing full protective clothing
and bounce up and down a few times to allow the rear wheel suspension
to become level.
– Stay on the bike and have another person measure the distance between
the same two points and write it down as dimension C.
– The riding sag is the difference between dimensions A and C.
EXAMPLE:
Motorcycle jacked up (dimension A) . . . . . . . . . . . . . . . . . . . . . . . .600 mm
Motorcycle on ground, loaded (dimension C) . . . . . . . . . . . . . . . .– 510 mm
Riding sag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90 mm
The riding sag should lie between 90 and 105 mm.
If the riding sag is less than 90 mm, the spring is too hard (the spring rate is
too high). If the riding sag is more than 105 mm, the spring is too soft (the
spring rate is too low).
The spring rate is written on the outside of the spring (e.g. 80/250). The
type number of the shock absorber is embossed on the bottom of the tank.
The illustrations show which spring should be installed. The standard spring
is shown in bold print (e.g. 1218Y767).
After installing a different spring, readjust the static sag to 35 mm (± 2 mm).