KTM 50 SX JUNIOR - Manual (Page 31)

ENGLISH
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Adjusting the centrifugal clutch *
A correctly adjusted centrifugal clutch will provide maximum engine perform-
ance and ease of driving and prevent the engine from overheating. Clutch wear
can affect the clutch engagement speed.
The clutch will slip for a longer period of time at higher clutch engagement
speeds, generating more frictional heat and causing the engine to overheat.
If the clutch engagement speed is too low, the engine will not reach the per-
formance range. In both cases, the engine will not seem to have enough power.
Check the clutch engagement speed every 20 hours and correct if necessary
or have it corrected by an authorized KTM workshop.
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To tune your clutch, lay the bike on the left side. To prevent oil from leaking
from the transmission vent hose, run the hose upwards and fasten. Remove
the screws [1] and the clutch cover [2] and discard the gasket.
Block the centrifugal clutch [3] with a suitable driver [4].
NOTE: insert the driver through both holes in the primary drive's drum and
gear wheel.
Loosen the nut [5] on the clutch and pull out the driver.
Remove the nut and shim from the crankshaft.
Screw the extractor (special tool item no. 590.29.021.044) onto the clutch
hub [6] with the M5x50 screws, hold the extractor and remove the centrifu-
gal clutch from the crankshaft by screwing in the extractor screw.
Completely remove the centrifugal clutch, bearings and spacing washers from
the crankshaft.
Loosen the HH screws [7] and remove the clutch shoes [8] from the clutch
hub [6]. Remove the HH screws and bushings [9], the spring sets [10] and
the disks [11] from the clutch shoes.
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ADJUSTING THE CLUTCH ENGAGEMENT SPEED:
The spring sets contain 14 spring washers [12] that need to be positioned on
top of each other in the order shown in the illustration [A].
Washers are located between the spring sets and the clutch shoes to preten-
sion the spring sets. You can influence the clutch engagement speed by pre-
tensioning the spring set. 0.5 mm more pretension will increase the clutch
engagement speed by approx. 500 rpm.
The clutch engagement speed is the speed at which the clutch begins to engage
and the motorcycle starts to drive off. The clutch engagement speed is 8500-
9000 rpm for the 50 LC engine.
NOTE: a tachometer (special tool item no. 451.29.075.000) to test the clutch
engagement speed is available from your KTM dealer.
Make sure the spring sets are not soiled during service or repair work to the
clutch since this can cause them to malfunction.
MAINTENANCE WORK ON CHASSIS AND ENGINE
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