COMPONENT LOCATION
• This section covers maintenance of the cylinder and piston. These procedures can be done with the engine installed in the frame.
• Before disassembly, clean the engine thoroughly to prevent dirt from entering it.
• Be careful not to damage the mating surfaces when removing the cylinder. For example, do not use a screwdriver to pry the cylinder.
• Clean all disassembled parts with cleaning solvent before inspection, use compressed air to dry the parts.
• Under racing conditions, the piston and piston rings should be replaced after 15.0 hours of operation. Replace the piston pin after 30.0 hours of operation.
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Unit: mm (in |
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ITEM |
STANDARD |
SERVICE LIMIT |
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|
Cylinder |
I. D. |
96.000 - 96.015 (3.7795 - 3.7801) |
96.025 (3.7805) |
|
Out of round |
- |
0.010 (0.0004) |
|
|
Taper |
- |
0.010 (0.0004) |
|
|
Warpage |
- |
0.05 (0.002) |
|
|
Piston, piston ring |
Piston mark direction |
"IN" mark facing toward the intake side |
- |
|
Piston O. D. |
95.970 - 95.980 (3.7783 - 3.7787) |
95.94 (3.777) |
|
|
Piston O. D. measurement point |
5.0 mm (0.20 in) from the bottom of skirt |
- |
|
|
Piston pin bore I. D. |
19.002 - 19.008 (0.7481 - 0.7483) |
19.03 (0.749) |
|
|
Piston pin O. D. |
18.994 - 19.000 (0.7478 - 0.7480) |
18.98 (0.747) |
|
|
Piston-to-piston pin clearance |
0.002 - 0.014 (0.0001 - 0.0006) |
0.04 (0.002) |
|
|
Top ring mark |
"R" mark side facing up |
- |
|
|
Piston ring-to-ring groove clearance |
Top |
0.065 - 0.100 (0.0026 - 0.0039) |
0.115 (0.0045) |
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Piston ring end gap |
Top ring |
0.25-0.31 (0.010-0.012) |
0.45 (0.018) |
|
Oil ring (side rail) |
0.20-0.70(0.008-0.028) |
0.90 (0.035) |
|
|
Cylinder-to-piston clearance |
0.020 - 0.045 (0.0008 - 0.0018) |
0.085 (0.0033) |
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|
Connecting rod small end I. D. |
'05 - '07 |
19.016 - 19.034 (0.7487 - 0.7494) |
19.04 (0.750) |
|
After '07 |
19.016 - 19.038 (0.7487 - 0.7495) |
19.04 (0.750) |
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|
Connecting rod-to-piston pin clearance |
'05 - '07 |
0.016 - 0.040 (0.0006 - 0.0016) |
0.06 (0.002) |
|
After '07 |
0.016 - 0.044 (0.0006 - 0.0017) |
0.06 (0.002) |
Cam chain tensioner lifter mounting bolt 12 N-m (1.2 kgf-m, 9 Ibf ft)
• Engine top-end problems usually affect engine performance. These problems can be diagnosed by a compression test or by tracing engine noise to the top-end with a sounding rod stethoscope.
• If the performance is poor at low speeds, check for white smoke in the crankcase breather hose. If the hose is smoky, check for a seized piston ring.
Compression too low, hard starting or poor performance at low speeds
• Leaking cylinder head gasket
• Worn, stuck or broken piston rings
• Worn or damaged cylinder and piston
• Loose spark plug
Compression too high, over-heating or knocking
• Excessive carbon build-up in cylinder head or on top of piston
Abnormal noise
• Worn cylinder and piston
• Worn piston pin or piston pin hole
• Worn connecting rod small end
• Worn connecting rod big end
Excessive smoke
• Worn cylinder, piston and piston rings
• Improper installation of piston rings
• Scored or scratched piston or cylinder wall
Remove the cylinder head (page 9-24). Remove the cam chain guide.
CAM CHAIN GUIDE
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CYLINDER |
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GASKET |
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BOLTS |
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Remove the bolts, cam chain tensioner lifter and gasket. Remove the bolt and cylinder. |
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BOLT |
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CAM CHAIN TENSIONER LIFTER |
