Yamaha RS90K, Service Manual

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INSP
ADJ
CLUTCH/
GEAR SELECTION
The clutch may require tuning depending upon
where the machine will be operated and the desired
handling characteristics. The clutch can be tuned
by changing the engagement and shifting speeds.
Clutch engagement speed is defined as the engine
speed at which the machine first begins to move
from a complete stop.
Clutch shifting speed is defined as the engine
speed reached when the machine has travelled
800 m (2,500 ft) after being started at full-throttle
from a dead stop.
Normally, when a machine reaches shifting speed,
the vehicle speed increases but the engine speed
remains nearly constant. Under unfavorable condi-
tions (wet snow, icy snow, hills, or rough terrain),
however, engine speed may decrease after the
shifting speed has been reached.
È
Engine speed
É
Good condition
Ê
Clutch shifting speed
Ë
Clutch engagement speed
Ì
Starting position
Í
Distance travelled 800 m (2,500 ft)
GEAR SELECTION
The reduction ratio of the driven gear to the drive
gear must be set according to the snow conditions.
If there are many rough surfaces or unfavorable
snow conditions, the drive/driven gear ratio should
be increased. If the surfaces are fairly smooth or
better snow conditions exist, decrease the ratio.
Gear ratio chart
The drive and driven gears and the chains shown in
the gear ratio chart are available as options. The
figures containing a decimal point represent the
drive/driven gear ratios, while the bottom numbers
designate the number of links in the chain.