KTM 65 SX 2009, Repair Manual

Page: 67 / 135

30/ENGINE - WORK ON INDIVIDUAL PARTS
65
0 0 A A
400548-10
–
Measure the piston at a distance

from the piston head, at right angles to the pis-
ton pin.
Guideline
Distance

32.0 mm (1.26 in)
Piston - diameter
Size 1 44.955… 44.965 mm (1.76988…
1.77027 in)
Size 2 44.965… 44.975 mm (1.77027…
1.77067 in)
300528-10
–
Piston size

is marked on the piston head.
16.9
Determining the piston/cylinder mounting clearance
–
Check/measure the cylinder. ( p. 64)
–
Determine the piston/cylinder mounting clearance. ( p. 65)
–
The smallest piston/cylinder mounting clearance is the result of the smallest cylinder bore diameter minus the largest piston diam-
eter. The largest piston/cylinder mounting clearance is the result of the largest cylinder bore diameter minus the smallest piston
diameter.
Guideline
Piston/cylinder - mounting clearance
New condition 0.060… 0.085 mm (0.00236… 0.00335 in)
Wear limit 0.10 mm (0.0039 in)
16.10
Checking the piston ring end gap
0 0
B B
400542-10
–
Remove the piston ring from the piston.
–
Place the piston ring in the cylinder and align it with the piston.
Guideline
Under the upper edge of the cylinder 10 mm (0.39 in)
–
Measure the end gap

using a feeler gauge.
Guideline
Piston ring end gap
≤
0.60 mm (
≤
0.0236 in)
» If the end gap is more than the specified value:
–
Check/measure the cylinder. ( p. 64)
» If the cylinder wear is within the tolerance range:
–
Change the piston ring.
16.11
Checking the reed valve housing, diaphragm and intake flange
300817-10
–
Check reed valve housing

for damage and wear.
» If there is damage or wear:
–
Change the reed valve housing.
–
Check the diaphragm for damage and wear.
» If there is damage or wear:
–
Change the diaphragm.
–
Check intake flange

for damage and wear.
» If there is damage or wear:
–
Change the intake flange.
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