Suzuki RM250 Owner's Service Manual page 84

• Remove carbon deposits from piston ring and piston ring
groove.
• Measure the clearances with the thickness gauge.
 Piston ring to groove clearance
Standard: 0.02 – 0.06 mm (0.0008 – 0.0024 in)
 09900-20803: Thickness gauge
• Remove the piston rings from the piston ring grooves.
• Fit the piston ring into the cylinder and measure the piston
ring end gap with the thickness gauge.
 Piston ring end gap
Service limit: 0.80 mm (0.031 in)
 09900-20803: Thickness gauge
• Measure the piston ring free end gap.
 Piston ring free end gap
Service limit: 6.6 mm (0.26 in)
 09900-20101: Vernier calipers
CYLINDER, PISTON AND EXHAUST VALVE 6-9