KTM 2011 690 SMC AUS, Repair Manual

Page: 128 / 229

16 ENGINE
126
–
Check the piston rings for damage.
» If the piston ring is damaged:
–
Change the piston ring.
Info
Mount the piston ring with the marking facing upward.
–
Check the piston pin for discoloration or signs of wear.
» If the piston pin has strong discoloration/signs of wear:
–
Change the piston pin.
–
Insert the piston pin into the connecting rod and check the bearing for play.
» If the piston pin bearing has too much play:
–
Change the connecting rod and the piston pin.
301758-10
–
Measure the piston at the piston skirt, at right angles to the piston pin, at a
distance
B
.
Guideline
Distance
B
31.5 mm (1.24 in)
Piston - diameter
Size I 101.955… 101.965 mm (4.01397…
4.01436 in)
Size II 101.965… 101.975 mm (4.01436…
4.01476 in)
Info
Piston size
1
is marked on the piston head.
16.4.14 Checking piston ring end gap
300098-10
–
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 with a feeler gauge
A
.
Guideline
Piston ring end gap
Compression rings
≤
0.80 mm (
≤
0.0315 in)
Oil scraper ring
≤
1.00 mm (
≤
0.0394 in)
» If the end gap is more than the specified value:
–
Check/measure the cylinder. ( p. 125)
» If the cylinder wear is within the tolerance range:
–
Change the piston ring.
–
Mount the piston ring with the marking facing toward the piston head.
16.4.15 Checking piston/cylinder mounting clearance
–
Check/measure the cylinder. ( p. 125)
–
Check/measure the piston. ( p. 125)
–
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 0.035… 0.060 mm (0.00138… 0.00236 in)
Wear limit 0.10 mm (0.0039 in)