Removing Carbon From Cylinder Head; Replacing The Valve Guides; Re-Cutting The Valve Seats; Assembling The Cylinder Head - Triumph SPEED TWIN 1945 Workshop Instruction Manual

Clean the valves and remove any b u r n t o i l f r o m the stems;
if
t h e valve faces are
pitted they can be re-ground, b u t excessive grinding by machine is n o t advisable as
t h e heat transference o f t h e valve w i l l be adversely affected. The stem o f the valve
should be inspected f o r wear and scuffing and if either is pronounced,
it
should b e
replaced.
R e m o v i n g C a r b o n f r o m C y l i n d e r H e a d . Remove t h e carbon w i t h a
f l a t
r o u n d
headed scraper from the head spheres and ports. Take particular care when cleaning
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around the valve seatings to,avoid damage t o t h e faces.
Inspect the valve seats f o r
pitting o r pocket~ng and the valve guidesfor ovality. Remember, i f thevalve guides are
changed, the valve seatings must be re-cut. T h e same applies t o a valve replacement
l o r a valve wliich has had the
seating
face re-ground.
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G r i n d i n g - i n t h e Valves. This should be done w i t h a fine carborundum grinding-in
paste. First smear a l i t t l e grease around the valve face and insert the stem i n t o t h e
new valve guide. Attach the valve grinding t o o l t o the stem t i p and commence t o
grind the valve face t o the valve seating, using a semi-rotary movement, occasionally
lifting the valve and turning through 180'. Continue this process until a uniform seat
results. Remove the valve and wash thoroughly i n petrol o r parafin and examine
the seating. A surer method i s t o apply a t h i n even smear of "Engineers' marking
blue" t o the face o f the valve. Rotate the valve one complete revolution and t h e n
remove
it
for inspection.
.
.
R e p l a c i n g t h e V a l v e Guides.
T o remove t h e old guide place a shoulder d r i f t
i n t o the guide from the inside of t h e combustion chamber and drive out. W h e n
fitting the new guide, grease the o u t e r diameter and drive i n t o the cylinder head
from the top. 'Always use a shoulder d r i f t when doing this operation and drive
i n the guide carefully t o avoid damage.
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A thin uniform line. free from p i t marks o r other surface blemishes o n valve face and
valve seat indicates that the seating is satisfactory. A f t e r completion, the part must
be thoroughly washed t o remove all traces of the grinding-in compound.
R e - c u t t i n g t h e V a l v e Seats. A job such as this can normally be undertaken by
your dealer
a t
a moderaie cost. A f t e r the seats have been re-cut, they should be
blended t o give an even seatlng of approx~mately (2.38 mm.).
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A s s e m b l i n g t h e C y l i n d e r H e a d . First e n s u r e i h a t all parts are thoroughly clean,
then oil the valve stems and guides. Place a valve i n t o its respective guide ( N o t e
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inlet are marked "IN" and exhaust "EX".) and holding the valve head against t h e
seat, t u r n the head o n
i t s
side and fit phe lower spring cup over t h e guide and then
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the inner and outer spring and finally t h e t o p collar. Compress the springs w i t h a
Compressor tool until the split cotters can be fitted i n t o t h e cpllar and around t h e
valve stem cut-away. .Release the pressure'on the compressor t o o l and remove.
Tap the stem head of the valve smartly t o ensure correct replacement of the cotters.
Repeat the operation t o the other valves. The exhaust pipe stubs on the T100.
are screwed i n t o the exhaust ports and tightness must be ensured before replacing
the cylinder head.
D o not replace the rocker boxes at this stage.