Honda NSS250A Reflex 2001-2007, Manual

Page: 323 / 718

CYLINDER/PISTON
10-3
SERVICE INFORMATION
GENERAL
• This section covers maintenance of the cylinder and piston.
• The cylinder and piston can be serviced with the engine installed in the frame.
• Be careful not to damage mating surfaces when removing the cylinder.
• Take care not to damage the cylinder wall and piston.
• Clean all disassembled parts with clean solvent and dry them using compressed air before inspection.
SPECIFICATIONS
Unit: mm (in)
TROUBLESHOOTING
Compression too low, hard starting or poor performance at low speed
• Worn, stuck or broken piston rings
• Worn or damaged cylinder and piston
• Cylinder head/valve problem (page 9-13)
Compression too high, overheating or knocking
• Excessive carbon build-up on piston head or on combustion chamber
Excessive smoke
• Worn cylinder, piston or piston rings
• Improper installation of piston rings
• Scored or scratched piston or cylinder wall
• Cylinder head/valve problem (page 9-13)
Abnormal noise
• Worn piston pin or piston pin hole
• Worn connecting rod small end
• Worn cylinder, piston or piston rings
ITEM STANDARD SERVICE LIMIT
Cylinder I.D. 68.000 – 68.010 (2.6772 – 2.6776) 68.10 (2.681)
Out-of-round – 0.05 (0.002)
Taper – 0.05 (0.002)
Warpage – 0.05 (0.002)
Piston, piston
pin, piston
ring Piston O.D. at 14 (0.6) from bottom 67.970 – 67.990 (2.6760 – 2.6768) 67.90 (2.673)
Piston pin hole I.D. 17.002 – 17.008 (0.6694 – 0.6696) 17.04 (0.671)
Piston pin O.D. 16.994 – 17.000 (0.6691 – 0.6693) 16.96 (0.668)
Piston-to-piston pin clearance 0.002 – 0.014 (0.0001 – 0.0006) 0.02 (0.001)
Piston ring end gap
Top 0.15 – 0.25 (0.006 – 0.010) 0.45 (0.018)
Second 0.30 – 0.45 (0.012 – 0.018) 0.65 (0.026)
Oil (side rail) 0.20 – 0.70 (0.008 – 0.028) 0.90 (0.035)
Piston ring-to-ring
groove clearance Top 0.020 – 0.050 (0.0008 – 0.0020) 0.09 (0.004)
Second 0.015 – 0.045 (0.0006 – 0.0018) 0.085 (0.0033)
Cylinder-to-piston clearance 0.010 – 0.040 (0.0004 – 0.0016) 0.10 (0.004)
Connecting rod small end I.D. 17.010 – 17.028 (0.6697 – 0.6704) 17.05 (0.671)
Connecting rod-to-piston pin clearance 0.010 – 0.034 (0.0004 – 0.0013) 0.05 (0.002)
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