Honda NSS250S Manual page 323

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
Cylinder I.D.
Out-of-round
Taper
Warpage
Piston, piston Piston O.D. at 14 (0.6) from bottom
pin, piston
Piston pin hole I.D.
ring
Piston pin O.D.
Piston-to-piston pin clearance
Piston ring end gap
Piston ring-to-ring
groove clearance
Cylinder-to-piston clearance
Connecting rod small end I.D.
Connecting rod-to-piston pin clearance
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
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ITEM
Top
Second
Oil (side rail)
Top
Second
STANDARD
68.000 – 68.010 (2.6772 – 2.6776)
–
–
–
67.970 – 67.990 (2.6760 – 2.6768)
17.002 – 17.008 (0.6694 – 0.6696)
16.994 – 17.000 (0.6691 – 0.6693)
0.002 – 0.014 (0.0001 – 0.0006)
0.15 – 0.25 (0.006 – 0.010)
0.30 – 0.45 (0.012 – 0.018)
0.20 – 0.70 (0.008 – 0.028)
0.020 – 0.050 (0.0008 – 0.0020)
0.015 – 0.045 (0.0006 – 0.0018)
0.010 – 0.040 (0.0004 – 0.0016)
17.010 – 17.028 (0.6697 – 0.6704)
0.010 – 0.034 (0.0004 – 0.0013)
CYLINDER/PISTON
Unit: mm (in)
SERVICE LIMIT
68.10 (2.681)
0.05 (0.002)
0.05 (0.002)
0.05 (0.002)
67.90 (2.673)
17.04 (0.671)
16.96 (0.668)
0.02 (0.001)
0.45 (0.018)
0.65 (0.026)
0.90 (0.035)
0.09 (0.004)
0.085 (0.0033)
0.10 (0.004)
17.05 (0.671)
0.05 (0.002)
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