Crankshaft; Piston; Piston Ring End Gap - KTM 85 SX 2004 Repair Manual

Crankshaft

– When replacing the roller bearing, the inner crankshaft ring must also
be renewed.
– Heat special tool 584.29.037.031 on a heating pad up to approx.
150°C and slip it on the inner ring immediately. Press the special tool
together tightly so as to obtain a good heat transfer and pull the
inner ring off the crankshaft.
– To mount the new inner ring, heat the special tool again to approx.
150°C, engage the inner ring and slip it on the crankshaft journal
immediately. Make sure the inner ring is pushed back to the stop.
!
N
EVER CLAMP THE CRANKSHAFT WITH A STUD OR WEB IN THE VICE
TO KNOCK THE BEARING INNER RING FREE
-
COMPRESSED AND THE CON ROD PLUG AND BEARING MAY BE DAMAGES
MAKING THE CRANKSHAFT UNUSABLE
NOTE: Distance adjustment of the main bearings is not requested.

Piston

If a used piston is to remain in service then the following should be
checked:
1. Piston running surface: Check for pressure marks (seizing marks)
minor friction marks can be removed with a fine abrasive stick.
2. Piston ring groove: The piston ring may not jam in the groove. Use an
old piston ring or sandpaper (400 grit) to clean the groove.
3. The piston ring anti-rotation device must fit tightly in the piston and
may not be worn.
4. Check piston rings for wear and check end gap.
– The piston is measured at the piston skirt, transverse to the piston pin
32 mm below the top, as shown in the illustration.
– The smallest cylinder diameter minus the largest piston diameter
determines the piston fitting clearance.
Piston fitting clearance: 0.045 - 0.07 mm

Piston ring end gap

– Insert piston ring into the cylinder and adjust. Piston ring must be
approx. 10 mm from top of cylinder.
B
– The end gap can now be checked with a feeler gauge.
Piston ring end gap: max. 0.30 mm
NOTE: If the end gap is greater check piston and cylinder for wear. If
piston and cylinder wear are within the permitted tolerance limits,
replace the piston ring.
CAUTION
. T
HE CRANKSHAFT WEBS MAY BE
.
5-4
!
,
AND NEVER TRY
,
THEREBY