Checking Piston Ring End Gap; Checking Piston/Cylinder Mounting Clearance - KTM 690 enduro R EU Repair Manual

17 ENGINE

17.4.14 Checking piston ring end gap

17.4.15 Checking piston/cylinder mounting clearance

–
Check/measure the cylinder. (
–
Check/measure the piston. (
–
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
Wear limit
–
Check the piston rings for damage.
» If the piston ring is damaged:
–
Change the piston ring.
–
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.
–
Measure the piston at the piston skirt, at right angles to the piston pin, at a
distance
B
Guideline
Distance
Piston - diameter
Size I
Size II
301758-10
Info
Piston size
–
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
–
Measure the end gap with a feeler gauge
Guideline
Piston ring end gap
Compression rings
300098-10
Oil scraper ring
» If the end gap is more than the specified value:
–
Check/measure the cylinder. (
» 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.
p. 131)
p. 131)
Info
Mount the piston ring with the marking facing upward.
.
B
is marked on the piston head.
1
0.035... 0.060 mm (0.00138... 0.00236 in)
0.10 mm (0.0039 in)
31.5 mm (1.24 in)
101.955... 101.965 mm (4.01397...
4.01436 in)
101.965... 101.975 mm (4.01436...
4.01476 in)
10 mm (0.39 in)
.
A
≤ 0.80 mm (≤ 0.0315 in)
≤ 1.00 mm (≤ 0.0394 in)
p. 131)
132