Honda TRX680FA Service Manual page 229

CYLINDER/PISTON
SERVICE INFORMATION
GENERAL
• The cylinder and piston can be serviced with the engine installed in the frame.
• Take care not to damage the cylinder wall and piston.
• Be careful not to damage the mating surfaces when removing the cylinder.
• Rocker arm and valve lubricating oil is fed through the oil passage in the cylinder. Clean the oil passage before install-
ing the cylinder.
• When disassembling, mark and store the disassembled parts to ensure that they are reinstalled in their original loca-
tions.
SPECIFICATIONS
Unit: mm (in)
ITEM
Cylinder
Piston,
piston pin,
piston ring
I.D.
Out-of-round
Taper
Warpage
Piston O.D. at 20 (0.8) from bottom
Piston pin hole I.D.
Piston pin O.D.
Piston-to-piston pin clearance
Piston ring end
gap
Piston ring-to-ring
groove clearance
Top
Second
Oil (side rail)
Top
Second
Cylinder-to-piston clearance
Connecting rod small end I.D.
Connecting rod-to-piston pin clearance
STANDARD
102.000 - 102.015 (4.0157 - 4.0163)
-
-
-
101.960 - 101.990 (4.0142 - 4.0153)
23.002 - 23.008 (0.9056 - 0.9058)
22.994 - 23.000 (0.9053 - 0.9055)
0.002 - 0.014 (0.0001 - 0.0006)
0.25-0.35(0.010-0.014)
0.40-0.55(0.016-0.022)
0.20-0.70(0.008-0.028)
0.045 - 0.080 (0.0018 - 0.0031)
0.025 - 0.060 (0.0010 - 0.0024)
0.010 - 0.055 (0.0004 - 0.0022)
23.030 - 23.050 (0.9067 - 0.9075)
0.030 - 0.056 (0.0012 - 0.0022)
SERVICE LIMIT
102.05(4.018)
0.05 (0.002)
0.05 (0.002)
0.05 (0.002)
101.90(4.012)
23.03 (0.907)
22.98 (0.905)
0.04(0.002)
0.5 (0.02)
0.7 (0.03)
0.9 (0.04)
0.095 (0.0037)
0.075 (0.0030)
0.19 (0.007)
23.06 (0.908)
0.08 (0.003)
TORQUE VALUES
Cylinder stud bolt See page 10-7
TROUBLESHOOTING
Compression too low, hard starting or poor performance at low speed
• Leaking cylinder head gasket
• Worn, stuck or broken piston ring
• Worn or damaged cylinder and piston
Compression too high, overheating or knocking
• Excessive carbon built-up on piston head or combustion chamber
Excessive smoke
• Worn cylinder, piston or piston rings
• Improper installation of piston rings
• Scored or scratched piston or cylinder wall
Abnormal noise
• Worn piston pin or piston pin bore
• Worn connecting rod small end
• Worn cylinder, piston or piston rings
10-3