Breather Plug Front Fork; Cleaning The Dust Sleeves Of The Telescopic Fork; Adjusting The Spring Preload On The Fork (Sx) - KTM 400 Owner's Handbook Manual

Breather plug front fork

After every 5 hours of use for competitive racing, slacken the breather
1
plugs a few turns in order to relieve excess pressure from the inside of
the fork. To do this, place the motorcycle on a stand with the front wheel
lifted off the ground. When riding the motorcycle mainly on street, it will be
enough to have this job performed in the course of the periodical mainten-
1
ance service.
! CAUTION !
E . I
XCESSIVE PRESSURE IN THE INTERIOR OF THE FORK CAN CAUSE LEAKS IN THE FORK F
,
YOUR FORK IS LEAKING IT IS RECOMMENDED TO OPEN THE BREATHER PLUGS BEFORE
.
HAVING THE SEALS REPLACED

Cleaning the dust sleeves of the telescopic fork

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The dust-protection bellows are to remove dust and coarse dirt particles
from the fork tube. However, after some time, dirt may also get in behind
the dust-protection bellows. If this dirt is not removed, the oil sealing rings
located behind it may start to leak.
Use a screwdriver to lever the dust-protection bellows out of the outer
tubes and slide them downward.
2
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Clean dust-protection bellows, outer tubes, and fork tubes thoroughly, and
oil them thoroughly with silicone spray or engine oil. Then, push dust-pro-
tection bellows into the outer tubes by hand.

Adjusting the spring preload on the fork (SX)

The spring preload on the SX models can be adjusted (changed) by 10 mm
by turning adjusting screw 3.
Turning in a clockwise direction will increase the prestress, turning in a
counterclockwise direction will decrease the prestress.
Changing the spring preload will not affect the rebound damping adjust-
ment.
Generally, if the spring preload is higher, the rebound damping should also
be set higher.
3
Standard setting:
Unscrew the adjusting screw to the limit and then back 2 turns.
3