Royal Enfield 250 CLIPPER, Руководство по техническому обслуживанию мастерской

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ROYAL ENFIELD WORKSHOP MANUAL
PAGE 20
cup and grind it on to its seat with a backwards
and forwards semi-rotary motion. Alternatively, a
tool which pulls on the valve stem may be used.
Frequently lift the valve and move it round so
that an even and true seating is obtained. If no
light spring is available, the lifting will have to be
done by hand. Continue grinding until a bright
ring is visible on both the valve and seating.
The face and seat of the exhaust valve is cut at
45° but the profile of the inlet valve is of a special
streamlined design as shown in Fig. 4 which
eliminates pockets and sharp edges and allows a
smooth flow of gas without eddies.
If the valves or their seats are pitted and
require recutting, care must be taken to
reproduce the correct profile.
The cylinder head should preferably be
returned to the Works for the inlet valve seat to
be re-cut but, if this is not possible, Special Valve
Cutting Tools No. E2178, T1891 and Arbor
T2053 are available for this purpose. Great care
must be exercised in using this tool as it is located
off the valve guide and this may be damaged if
suitable apparatus is not employed.
The inlet valve face and seat can be cut at 45°
in case of expediency but this may have a
deleterious effect on the performance of the
engine.
21. Re-assembly after Decarbonising
Before building up the engine, see that all
parts are scrupulously clean and place them
conveniently to hand on a clean sheet of brown
paper.
It is advisable to fit a new gasket to the
cylinder head and a new paper washer at the
cylinder base.
Check the piston ring gaps to find out
whether excessive wear has taken place (see
Subsection 19).
Smear clean oil over the piston and space the
ring gaps, having replaced the rings if these have
been removed, lower the piston over the
connecting rod and insert the gudgeon pin. Fit
the circlip securing the gudgeon pin, making sure
that it seats correctly in its groove.
Oil the cylinder bore and lower the barrel
over the piston and seat it gently on the gasket.
Drop the push rods down their tunnel into
the cups on the cam followers. Note that the
shorter rod is the exhaust and is nearest the
cylinder.
Fit the cylinder head gasket and replace the
cylinder head as described in Subsection 13.
After the engine has been assembled, run it
for a brief period at a speed which will ensure
that the ignition has been advanced by the
C18
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