Piston - Suzuki UY125 Service Manual

3-34 ENGINE

PISTON

PISTON DIAMETER
Using a micrometer, measure the piston outside diameter at the
place 10 mm from the skirt end as shown. If the measurement is
less than the limit, replace the piston.
& Piston diameter
Service Limit: 53.380 mm
$ 09900-20203: Micrometer (50 – 75 mm)
PISTON-TO-CYLINDER CLEARANCE
• Subtract the piston diameter from the cylinder bore diameter.
(!3-33)
• If the piston-to-cylinder clearance exceeds the service limit,
replace the crankcase set or the piston, or both.
& Piston to cylinder clearance
Service Limit: 0.120 mm
PISTON RING-TO-GROOVE CLEARANCE
• Measure the side clearances of the 1st and 2nd piston rings
using the thickness gauge.
• If any of the clearances exceeds the limit, replace both the
piston and piston rings.
& Piston ring-to-groove clearance
Service Limit (1st) : 0.180 mm
(2nd): 0.150 mm
& Piston ring groove width
Standard (1st) : 1.01 – 1.03 mm
(2nd): 1.01 – 1.03 mm
(Oil) : 2.01 – 2.03 mm
& Piston ring thickness
Standard (1st & 2nd): 0.97 – 0.99 mm
$ 09900-20205: Micrometer (0 – 25 mm)
09900-20803: Thickness gauge
NOTE:
Using a soft-metal scraper, decarbon the crown of the piston.
Clean the ring grooves similarly.
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10 mm