ENGINE PARTS CHECK
❱❘ Piston
•
In case of fitting an used piston, check the following points:
•
Skirt: Looking for seizure marks. Lights marks can be removed with
a soft stone.
•
Ring grooves: rings must be free in their grooves. In order to clean
the grooves, you can use an old ring.
•
The ring pins should not be worn or loose.
•
Rings : check condition and end gap
❱❘ End gap
•
Insert the ring in the cylinder, using the piston to make it square to the cylinder axis, to
about 10mm of the cylinder deck.
•
Measure end gap using a thickness gauge.
Ring end gap :
Standard :
125 : 0.35mm – 0.50mm
250 / 300 : 0.2mm – 0.4mm
If the end gap is greater than specified, you must check cylinder and piston condition. If
they are within tolerance, only replace the rings.
❱❘ Wrist pin check
Wrist pin diameter ; 125cc:
Standard : 14,998 mm
Wear limit : 14,995 mm
Wrist pin hole ; 125cc
Standard : 15,003mm
Wear limit : 15,007mm
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CAUTION
t
Wrist pin diameter ; 250/300cc
Standard : 17,998 mm
Wear limit : 17,995mm
Wrist pin hole ; 250/300cc
Standard : 18.002 mm
Wear limit : 18.006 mm
ST SERIES