F1298 Force ROUND HD SCREW W/LOCKWASHER, 6 - 32 X 1/4

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Disassembling sequence (1) Rocker cover (2) Adjusting screw (3) Bolt (short) (4) Bolt (long) (5) Valve cap (6) Snap ring (7) Rocker arm (8) Rocket shaft bracket (9) Rocket shaft spring (10) Rocket shaft (11) Push rod (12) Cylinder head bolt (13) Cylinder head (14) Valve cotter (15) Valve retainer (16) Valve spring (17) Inlet valve (18) Exhaust valve (19) Valve stem seal (20) Cylinder head gasketRemoving rocker shaft assembly
Note: Always loosen shorter bolts first. Failing to do so may damage the rocker shaft bracket.
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Loosen the rocker arm adjusting screws by rotating about one turn.
Loosen the shorter rocker bracket bolts first.
Then, loosen the longer rocker bracket bolts.
Remove the rocker bracket bolts, and remove the rocker shaft assembly from the cylinder head.
Remove push rods.Disassembling rocker shaft assembly
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Be sure to arrange the parts in order during disassembly. Keep the original combination of rocker arm and shaft assembly, and when reassembling. Make sure to install the rocker arm and shaft assembly in the original positions to restore the same clearance between the rocker shaft and rocker arm.
Do not remove the rocker bushing unless rocker bushing is defective or its inside diameter exceeds the limit.Removing cylinder head assembly
Note: When removing the cylinder head gasket, be careful not to damage the cylinder head or crankcase surface by tools such as a screwdriver.
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Remove the cylinder head bolt.
Remove the cylinder head assembly by lifting cylinder head assembly up.Note: If the cylinder head assembly cannot be removed due to crimping of the cylinder head gasket. Tap the thick area on the side of the cylinder head using a plastic hammer to give a shock.
Remove the gasket from the cylinder head.Note: If there is a cylinder head problem, check the bolts for tightness with a torque wrench before removing the cylinder head bolts.Removing valve and valve spring
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Using a valve spring pusher, compress the valve spring evenly and remove the valve cotters.Note: If valves are reusable, mark each valve seat and the mating valve guide for identifying the original positions. Do not mix valve seats with other valve guides.Removing valve stem seal
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Grab the stem seal with pliers and remove.Note: Be sure to replace the stem seal with the new one when reassembling the valve and valve spring.Cleaning cylinder head bottom surface
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Taking care not to damage the cylinder head bottom surface, remove residue of old gasket.Note: First, roughly scrape off residue of old gasket using a scraper. Then, grind off the remaining residue using an engine-oil immersed oil stone.Measuring piston protrusion
Note: Piston protrusion must always meet the standard. The amount of protrusion not only influences on the engine performance, but also it is important to prevent valve interference.
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Measure the protrusion of each piston following the instructions below. If the measured value exceeds the limit, inspect and repair each bearings.
Search the top dead center of the piston by using dial gauge.
Apply the dial gauge plunger to the top surface of the crankcase, and zero the dial gauge.
Measure the protrusion at three points on the piston head, and calculate the mean value. Subtract the mean value from the thickness of the gasket compressed by tightening the cylinder head. The clearance between the piston top and cylinder head will be determined.
Table 1
Item     Standard Dimension    
Piston protrusion (A)    
0.130 to 0.600 mm (0.0051 to 0.0236 inch)    
Compressed thickness of cylinder head gasket    
1.270 to 1.370 mm (0.0500 to 0.0539 inch)