Honda SH300I 2006, Manual

Page: 243 / 511

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 the mating surfaces when removing the cylinder.
• Take care not to damage the cylinder wall and piston.
• The rocker arm and camshaft lubricating oil is fed through the oil passage (stud bolt hole) in the cylinder. Clean the oil
passage before installing the cylinder.
SPECIFICATIONS
Unit: mm (in)
TROUBLESHOOTING
Compression too low, hard starting or poor performance at low speed
• Worn, stuck or broken piston ring
• Worn or damaged cylinder and piston
• Cylinder head/valve problem (page 9-5)
Compression too high, overheating or knocking
• Excessive carbon build-up on piston head or on combustion chamber
Excessive smoke
• Worn cylinder, piston or piston ring
• Improper installation of piston rings
• Scored or scratched piston or cylinder wall
• Cylinder head/valve problem (page 9-5)
Abnormal noise
• Worn piston pin or piston pin hole
• Worn connecting rod small end
• Worn cylinder, piston or piston rings
Piston ring sticking/scuffing, bearing damage
• Clogged oil gallery or oil strainer screen
• Internal oil leak
• Use of poor quality engine oil
ITEM STANDARD SERVICE LIMIT
Cylinder I.D. 72.000 – 72.010 (2.8346 – 2.8350) 72.045 (2.8364)
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 10 (0.4) from bottom 71.97 – 71.99 (2.833 – 2.834) 71.90 (2.831)
Piston pin hole I.D. 17.002 – 17.008 (0.6694 – 0.6696) 17.03 (0.670)
Piston pin O.D. 16.994 – 17.000 (0.6691 – 0.6693) 16.98 (0.669)
Piston-to-piston pin clearance 0.002 – 0.014 (0.0001 – 0.0006) 0.02 (0.001)
Piston ring end gap Top 0.15 – 0.30 (0.006 – 0.012) 0.50 (0.019)
Second 0.30 – 0.45 (0.012 – 0.018) 0.65 (0.026)
Oil (side rail) 0.20 – 0.70 (0.008 – 0.028) 1.00 (0.039)
Piston ring-to-ring
groove clearance Top 0.030 – 0.065 (0.0012 – 0.0026) 0.080 (0.0031)
Second 0.015 – 0.050 (0.0006 – 0.0020) 0.065 (0.0026)
Cylinder-to-piston clearance 0.010 – 0.040 (0.0004 – 0.0016) 0.10 (0.004)
Connecting rod small end I.D. 17.016 – 17.034 (0.6699 – 0.6706) 17.06 (0.672)
Connecting rod-to-piston pin clearance 0.016 – 0.040 (0.0006 – 0.0016) 0.06 (0.002)