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Adjustments for Competition 113
Front Suspension Adjustments
The CRF uses a pneumatic spring in the front fork.
The front fork spring rate can be adjusted by
changing the fork air pressure and oil capacity.
The forks on CRF’s are about right for riders
weighing between 170 lb (77 kg) and 200 lb (91
kg) (less riding gear). So if you're a heavier rider,
you have to go up on the oil capacity or air
pressure.
Do not adjust the oil capacity or PSF air pressure
to a level that is outside the minimum or maximum
levels.
PSF Air Pressure
• Adjust the PSF air pressure when the fork is cold
as follows:
1. Place an optional workstand under the engine,
so that the front wheel is off the ground.
2. Remove the valve caps and clean the area
around the PSF air valve (1).
3. Adjust the PSF air pressure.
Do not adjust the PSF air pressure to a level that is
outside the minimum or maximum levels.
The correct “cold” PSF air pressures are:
standard: 33 psi (230 kPa, 2.3 kgf/cm
2
)
with standard oil capacity:
The higher or lower PSF air pressure affects the
entire range of fork travel.
4. Check that there is no air leakage. If there is
any air leakage, replace the air valve assembly.
5. Make sure the valve stem caps are secure. If
necessary, install new caps.
If you need to adjust the PSF air pressure when the
front forks are warm (after driving), refer to page
30.
Oil capacity
• Adjust the oil capacity refer to Fork Assembly on
page 122.
Oil capacities are:
standard: 8.3 US oz (245 cm
3
)
When adjusting oil capacity, bear in mind that the
air in the fork will increase in pressure while
riding; therefore, the higher the oil capacity, the
higher the eventual pressure of any air in the fork.
with standard PSF air pressure:
The higher or lower oil capacity affects the final
3.9 in (100 mm) of fork travel.
Fork Springs
(1) PSF air valve
(1)
soft (minimum) 31 psi (220 kPa, 2.2 kgf/cm
2
)
standard 33 psi (230 kPa, 2.3 kgf/cm
2
)
medium-stiff 35 psi (240 kPa, 2.4 kgf/cm
2
)
stiff (maximum) 36 psi (250 kPa, 2.5 kgf/cm
2
)
12 (in)
(mm)
1086420
30025020015010050
700
3000
2500
2000
1500
1000
500
(lbf)(N)
600
500
400
300
200
100
Force (lbf/N)
PSF air pressure (MAX)
36 psi (250 kpa, 2.5 kgf/cm
2
)
PSF air pressure (STANDARD)
33 psi (230 kpa, 2.3 kgf/cm
2
)
PSF air pressure (MIN)
31 psi (220 kpa, 2.2 kgf/cm
2
)
Stroke (in/mm)
soft (minimum) 7.1 US oz (210 cm
3
)
standard 8.3 US oz (245 cm
3
)
stiff (maximum) 8.5 US oz (250cm
3
)
12(in)
(mm)
1086420
30025020015010050
700
3000
2500
2000
1500
1000
500
(lbf)(N)
600
500
400
300
200
100
Force (lbf/N)
Oil capacity (MAX)
8.5 US oz (250 cm
3
)
Oil capacity (STANDARD)
8.3 US oz (245 cm
3
)
Oil capacity (MIN)
7.1 US oz (210 cm
3
)
Stroke (in/mm)
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