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Cylinder Head
Before reassemble the cylinder head grind off the stepped portions of the port and
smooth the inside of ports to make intake/exhaust gas flow smooth.
Grind off the stepped portions only at the mating surface between the carburetor holder
and the intake port.
When using the kit camshaft (49118-0034), grind off the inside of the intake port to extent
1mm from the original port diameter for improve the performance.
Mark the carburetor holders so that they can be installed in their original positions.
Grind off and smooth the stepped portions at the mating surface between the valve seat
and the port.
Smooth the inside of the intake port and exhaust port.
Chamfer the machining edge of the cylinder head where the valve seat installed, also
smooth the dome of the combustion chamber with the valves installed. Excessive
smoothing may reduce the cylinder compression.
Use the hand grinder.
Use #200 oil stone for eliminating any stepped portion and #300 oil stone for finishing.
NOTE
These procedures make air resistance less and intake/exhaust gas flow more smooth.
However, much more effect can not be expected by excessive grinding and smoothing. It
may be done to the extent of getting rid of uneven surfaces.
A: Stepped Portions B: Grind off the rib to 5 mm
╳: Grind Area ( All around port )
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