Inspecting Piston And Piston Ring; Disassembling Crankcase - Yamabiko ECHO PB-2520 Service Manual

48

7-7 Inspecting piston and piston ring

A
E
F

7-8 Disassembling crankcase

B
D
G
A
ENGINE
1. Inspect piston ring (A) and replace it if broken,
scored, or exceeded service limits (Refer to "1-5
C
Service limits").
2. Inspect piston crown (B). Clean with ne sand
paper, oil stone, and soft cleaning brush (C) if car-
bon is found.
3. Inspect top land (D), ring groove and skirt (E).
Clean them with soft cleaning brush (C), if carbon
is found.
NOTE: Do not use square end of broken piston
ring when cleaning piston ring groove, otherwise
H
piston ring groove might be damaged.
4. Remove snap rings from both sides of piston
pin.
5. Push piston pin out from piston.
NOTE: If piston pin is tight, use piston pin tool
897702-30131 (F) with adapter (G) stamped "8" on
an end and piston holder 897719-02830 (H).
6. Inspect needle bearing and washers, and re-
place if wear or discoloration is noted.
1. Remove cylinder, gasket and piston.
2. Remove woodruf key from crankshaft ywheel
end.
3. Remove three crankcase bolts.
4. Screw M5 bolts (A) of length 65-75 mm (2.5 -3.0
in) to crankcase as shown.
5. Hold crankcase and alternately tap three bolts (A)
using plastic mallet to separate crankcase halves.
6. Clean inside of crankcase halves if dirty. Re-
place as a set if damaged.
7. Inspect crankshaft for roughness (crankshaft
runout), discoloration, or other damage. Replace it
with new one as required.
PB-2520
EB252