4 STROKES
CHECKING SHOCK ABSORBER STATIC SAG
Correct shock absorber static sag corresponds to a static lowering of
the motorcycle by 35 mm. Variations exceeding 2 mm may influence
motorcycle performance.
Procedure:
- Place the motorcycle on a stand so that the rear wheel does not touch
the ground.
- Measure the distance between the rear wheel pin and a fixed point (e.g.
a reference on a side) making sure that the straight line that connects
the wheel pin to the fixed point is as perpendicular to the ground as
possible and write down the value as measurement A.
- Place the motorcycle on the ground again.
- Ask someone to keep the motorcycle in an upright position.
- Measure the distance between the rear wheel pin and the fixed point
again and write the value down as measurement B.
- The static sag is the difference between measurements A and B.
EXAMPLE:
Motorcycle on stand (measurement A) ……………............................ mm 600 -
Motorcycle on the ground unladen (measurement B) ............. mm 565 =
Static sag ……………………………........................................................ mm 35
If the static sag is smaller, the shock absorber spring pre-load must
be decreased. If the static sag is greater, the spring pre-load must be
increased. See “Varying pre-load and replacing shock absorber spring”
chapter.
CHECKING SHOCK ABSORBER RIDER SAG
Correct shock absorber rider sag should correspond to a lowering of the
motorcycle of about 90-105 mm.
Procedure:
- Ask someone to help you hold the motorcycle. Sit on the bike wearing
full protective gear in normal position (feet on the footrests) and bounce
up and down a couple of times to normalise the rear suspension set
up.
- With the motorcycle loaded, measure the distance between the same
measurement points and write the value down as measurement C.
- The rider sag is the difference between measurements A and C.
EXAMPLE:
Motorcycle on stand (measurement A) ……..………..................... mm 600 -
Motorcycle on the ground with the driver (measurement C).... mm 510 =
Rider sag …………............................................................................ mm 90
If rider sag is less than 90 mm, the spring is too “hard” (spring rate too
high). If the rider sag is higher than 105 mm, the spring is too “soft”
(spring rate too low).
The spring rate is indicated on the spring wire. Once a different spring has
been assembled, the static sag must be readjusted to 35 mm (± 2 mm).
In our experience, after replacing the spring with one with a different
spring rate, the degree of compression damping can remain unvaried.
With a softer spring the degree of rebound damping can be reduced by
some clicks, and with a harder spring it can be increased by some clicks.
3.2 ADJUSTING SUSPENSIONS
A
B
C
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