|
8
|
On all 1972 models and 1971 models with the
locating groove adjacent to the inlet valve guide
shouider, ensure that the inlet guide to stem seals
are fitted and located correctly.
|
|
9
|
With the valve spring seat in position, loose
assemble the valve (with lightly lubricated stem)
inner and outer valve spring and top valve collar.
|
|
10
|
Using the valve spring compressor, compress the
collar and springs and insert the split valve
cotters
|
|
11
|
When the collets are firmly in position in the
valve stem groove, remove the compressor. The
cylinder head is now ready to refit.
|
|
|
SECTION C4
|
|
|
DECARBONISING
|
|
|
|
After the motorcycle has been in use for some
time, carbon deposits accumulate within the
combustion chamber and exhaust ports and also the
valves cease to seal completely due to wear and a
certain amount of burning on the valve seatings.
These conditions result in a lack of compression
and an increase in the compression ratio, giving
symptoms of a gradual loss of power, poor
compression and difficult starting. To remedy these
conditions it is necessary to remove the carbon
deposits and grind the valves to their seatings to
obtain a gas-tight seal. To do so, remove the
cylinder head (Section C1) and remove the valves
(Section C3).
|
|
|
|
Unless a carbon dispersant vat is available, the
carbon must be scraped from the combustion
chambers, exhaust ports and piston crowns. Since
the cylinder head and pistons are produced from an
aluminIum alloy material which is scratched easily,
the carbon must only be removed by a soft metal or
hard wood scraper which will not damage the
surface. A steel scraper or screw driver blade must
not be used. DO NOT remove the thin ring of carbon
round the top of each cylinder bore and leave also
a ring of carbon around the edge of each piston
crown. Removal of this carbon will tend to increase
the oil consumption.
|
|
|
|
The valve stems and heads shouid be scraped
clear of carbon but take care not to scratch the
facings. Examine the facings for deep pitting which
wouid render the valves unfit for re-use.
|
|
|
|
When ail parts are perfectly clean and in good
condition grind in the valves and reassemble.
|
|