Page 1 Fig. 65. Exploded View SHowING CYLINDER HEAD

Page 1 Fig. 65. Exploded View SHowING CYLINDER HEAD
The overhead rocker and valve assembly is shown in Fig. 72. Pre-1958 350 c.c.
“Clippers” and Models G, J, J2 have similar parts, but the exhaust push-rod
has a collar (for the exhaust-valve lifter) at its base, and ordinary nuts are used
instead of long sleeve-nuts to secure the cylinder head (below the head) to the
cylinder barrel. Slacken all nuts in a diagonal order. This 250 c.c. engine was
discontinued early in 1955.
(The Enfield Cycle Co., Ltd.)
10. Withdraw from above both push-rods 12 from their tubes or cast-in
tunnels (1956-7 350 c.c. “Clippers”). Should the collar (for the exhaust-
valve lifter) on the exhaust push-rod fail to clear the joint between the
cylinder head and the cylinder barrel, leave the exhaust push-rod in
position until the cylinder head has been removed.
11. Remove the four 1% in. nuts (sleeve-nuts, 250 c.c. “Clippers”) and
washers 13 (below the cylinder-head fins) from the inverted cylinder-head
studs 14.
12. Lift the cylinder head carefully and vertically from the cylinder
barrel 20. 1f the joint is stiff, tap the head carefully with a wooden mallet
or raw-hide hammer applied below the inlet and exhaust ports (not the
fins) until the head is freed. Inspect the copper gasket 16 which usually
comes away with the head. It may require to be annealed (see page 124)
before assembly. If there are any blackened areas indicating “blowing,” a
new gasket will have to be fitted. Do not forget to cover up the exposed
cylinder bore and piston with a clean cloth before removing the carbon
deposits (see page 119) from the piston, or proceeding with cylinder barrel
removal (if 1t 1s considered desirable to inspect the piston and rings). As
mentioned on page 107, too frequent removal of the cylinder barrel is not
To Remove Cylinder Head (1954-8 250 c.c. ““Clippers”’). Strip down
the engine and remove the cylinder head as just described for the Model
G, J, J2 engines, but disregard the previous hint (sub-paragraph 10,)
concerning the exhaust push-rod. The 250c.c. “Clippers” have no exhaust-
valve lifter, and therefore the exhaust push-rod has no collar at its base.
Mark one push-rod appropriately to ensure the rods not being inter-
changed during reassembly.
lo Remove Cylinder Head (1949-58 350 c.c., 500 c.c. “Bullets”:
1958 350 с.с. ““Clipper’’). Referring to Figs 66, 67, to remove the
cylinder head, strip-down the upper part of the engine thus—
1. Remove the petrol tank 1, the sparking plug 2, the carburettor 3, and
the exhaust system 4, as described on page 109 (sub-paragraphs 1-4).
Note that on some pre-1956 engines there is no flexible pipe between the
carburettor air-intake and the filter (as shown in Fig. 17). In this instance
after removing the flange-securing nuts, push the carburettor towards the
filter until the flange clears the securing studs, and then pull the carburettor
clear of the rubber clamp-ring inside the filter box.
2. Disconnect the engine steady 5 from the lug at the rear of the cylinder
3. Remove the two-way oil-feed pipe 6 to the separate rocker-boxes
after unscrewing the union nut 7 connecting the pipe to the front of the
crankcase, and the two union-screws and washers 8, which secure the
banjo ends of the composite pipe to the inlet and exhaust rocker-boxes.
Each move e Covers, > 10 nd gaskets 26 from both rocker-boxes
ceured by three long sleeve nuts 11 and |
nut 12. The shorter nut is at th Ker-bor and os
¢ front on the exhaust rocker-box
| - , and at
the rear on the inlet rocker-box. Note their positions for reassembly.
dicen émove the decompressor unit 13 from the cylinder head after first
necting the control cable from the handlebar lever (see page 106)
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Both engines have separate inlet and exhaust rocker-boxes. and a valve chess
which is integral with the crankcase,
6. Turn the engine over slowly so that the pi |
$ ISton 15 at top- -
with both valves fully closed (feel the overhead rockers). op-dead-centre,
7. Remove the eight 1 i
| 4 10. nuts and was ‹
bearing Caps. 5 hers 14 SECUTINO the rocker-
6. Remove as a unit each overhead-rocker assembly comprising: the
upper bearing-cap 15, the inlet or exhar
lower bearing-cap e exhaust rocker (see Fig. 72), and the
9. Withdraw from above both push-rods 17 |
changeable, the inlet push-rod being shorter than the exams rod er
10. Remove the four long sleeve-nuts, washers 18 (in pairs inside the
rocker-boxes) from the long crankcase studs 19 which secure the cylinder
head and cylinder barrel to the crankcase. Also remove the nut (located
on the near-side of the head ad; |
jacent to the sparkine pl
long crankcase-stud securing the head and barre! 5 PUS) from the fifth
7" Fel PE Ч р ln, =
I'l. Remove the nut and washer 20 from the short head-securing stud
“1 screwed into the top of the cylinder barrel on the off-side. It is also
idvisable to remove the $ in. nut and washer 22 (located just above the
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BOXES, CYLINDER BARREL, ETC., ON THE 1949-58 350 c.c., 500 c.c.
For valve spring details, see Fig. 72, Note that the reference numbers in Fig.
66 correspond to those in the above sketch.
(The Enfield Cycle Co, Ltd)
tappet chest) from the short crankcase-stud. This will avoid the risk of
damaging the stud when all the other vertical crankcase-studs have had
their nuts removed as described above.
12. Lift the cylinder head off the barrel vertically and with care until
it clears the five long crankcase-studs projecting through the cylinder
barrel and head (four of them into the rocker-boxes) and the shorter stud
projecting from the barrel on the off-side. If the head joint is stiff, tap it
carefully in the manner suggested on page 111 (sub-paragraph 12). Be
careful not to damage the gasket 23, and cover up the cylinder bore and
piston pending further dismantling or decarbonizing,
10 Remove Cylinder Barrel (1946-55 Models G, J, J2; 1956-7 350 c.c.
Clippers”). As stated on page 107, it is not good practice to disturb the
cylinder barrel each time you decarbonize. This applies to all engines.
Referring to Fig. 65 remove the cylinder barrel in the following manner —
1. Remove the cylinder head and copper gasket as described on page 109.
2. Turn the engine over slowly until the piston is at or near bottom-
dead-centre (B.D.C.).
3. Remove the cover and washer 17 from the tappet chest 18. This
exposes one of the five nuts (see Fig. 62) securing the cylinder barrel to the
crankcase. Remove all five nuts 19 from the crankcase studs. When doing
this first loosen all the nuts in a diagonal order.
4. Disconnect the exhaust-valve lifter control cable.
5. Lift the cylinder barrel 20 vertically upwards until its base clears the
crankcase studs, and the piston emerges. Steady the piston with the hand
and do not permit its skirt fo fall sharply against the connecting-rod, or the
rod against the edge of the crankcase mouth.
6. Cover up the crankcase hole with a clean cloth to prevent dirt or
foreign bodies entering the crankcase. This is a most important precau-
tion. Remove the joint washer 21 from the crankcase face; and renew it.
Paper washers are cheap and all such washers are best renewed. Clean
the joint faces thoroughly (see page 115).
To Remove Cylinder Barrel (1954-7 250 c.c. ‘‘Clippers’’). Follow the
instructions already given in respect of the 350 c.c. “Clipper” but dis-
regard sub-paragraph 4 above concerning the exhaust-valve lifter control
cable. On the small capacity coil-ignition models no valve lifter is needed
or provided.
To Remove Cylinder Barrel (1949-58 350 c.c., 500 c.c. ““Bullets’’: 1958
350 c.c. “Clipper”). Removal to spect the piston and rings is simple.
Referring to Fig. 67, remove the barrel as follows—
1. Remove the cylinder head and copper gasket as described on page 111.
2. Turn the engine over slowly until the piston is at or near bottom-
dead-centre (B.D.C.).
3. Check that the ¿ in. nut and washer 22 (located centrally above the
tappet chest) have been removed from the short stud on the off-side of the
4. Lift the cylinder barrel 24 vertically upwards until its lower fin
clears the crankcase studs and the piston emerges from the bore. Steady
the piston with one hand to prevent its skirt falling sharply against the
connecting-rod and to prevent the rod striking the edge of the crankcase
5. To prevent dirt or foreign matter entering the crankcase, and to
protect the piston, wrap a cloth round the connecting-rod and piston so
that it effectively blocks the hole in the crankcase. Remove and renew the
paper washer 25, and thoroughly clean up the barrel and crankcase joint
“Bullet” engines the piston crown
On the 1958 350 c.c. “Clipper” the
bearings are slightly different from those shown.
(The Enfield Cycle Co., Ltd.)
On the high-compression 350 c.c., 500 c.c.
is not flat, but dome-shaped (see Fig, 69).
faces. A carpenter’s scraper plate Is useful for removing jointing com-
pound without scratching or damaging the aluminium crankcase face.
I jeld engines 15 а
Removing the Piston. The piston fitted to Royal Enfie g $
split-skirt type (250 c.c. “Clippers” and “Bullets”) with two compression
rings and one slotted scraper ring (see Fig. 68). It is held to the small-en
| | -pin, d to the
of the connecting-rod by a fully floating gudgeon-pin, secure |
piston by two circlips. It is advisable to warm the piston before removing
the gudgeon-pin. This can be done by wrapping a cloth round the piston
after immersing the cloth in hot water and wringing it out.
Where a piston has been in service for a considerable mileage, it is
sometimes possible to push out the gudgeon-pin by hand, provided the
piston 1s reasonably warm. But it is generally necessary to press out the
gudgeon-pin by means of the special Royal Enfield extractor shown in
Fig. 69.
„ато both circlips (some owners remove only one circlip) after first
checking that the crankcase mouth is completely covered with a cloth.
Use a small screwdriver or a pointed instrument such as the tang end of a
suitable for piston removal and fitting on all sin |
gle-cylinder O.H.V.
À proprietary extractor such as the Terry is also suitable. es
(The Enfield Cycle Co., Ltd)
file to remove each circlip, which must subsequently be renewed. Having
removed the circlips, position the extractor tool (Part No. E5477) as
shown in Fig. 69 and fit the collar 4 on the spindle of the extractor. Then
turn the tommy bar anti-clockwise until the gudgeon-pin is drawn out
when the piston can be removed. It is not necessary to mark the piston,
If 1t 1s of the split-skirt type, as the split must be towards the front, but if
there IS no such identification, scribe a suitable mark on the inside of the
piston to ensure its being replaced in its original position when engine
assembly is undertaken. Before laying aside the gudgeon-pin, file a small
nick on one end to ensure that the pin is refitted in its original position
This 1s important. |
Inspecting and Removing Piston Rings. The piston rings are responsible
for maintaining good compression. Therefore they must be full of Spring
free in their grooves, and set with their slots opposite to each other (i е.
at 120° in the three-ring piston which is fitted on all Royal Enfield engines).
If all three rings are bright all the way round, they are obviously being
polished against the cylinder walls, and are perfect, and should be left
alone. If, on the other hand, they are discoloured at some points, they
are not in proper contact with the walls of the cylinder, causing gas to blow
past them. Perhaps they are stuck in their grooves with burnt oil, and will
function properly if the grooves are cleaned. If the rings are scored, or
have lost their tension, or are vertically loose in their grooves, or have
brown patches, the rings must be renewed.
Piston rings are of cast-iron and, being of very small section, must be
handled very, very carefully. If not, they will certainly be broken. Scraper
rings are particularly vulnerable; they cannot safely be opened out wider
than will allow them to slip over the crown of the piston. Therefore, to
Bore Stroke | Fuel ‘Oil
Model CR. | С.С. (mm) | (mm) al) | (pt)
G 6/1 346 | 70 90 23 4
J | 5-5/1 499 | 84 | 90 23 4
J2 | 5-5/1 . 499 34 90 24 4
“250 Clipper” 6-5/1 248 64 77 31 4
“350 Clipper” 6-5/1 346 70 90 | 3% 4
“350 Bullet” — 6-5/1* 346 70 90 | 3% 4
“500 Bullet” 6-5/1 499 84 + 90 — 3+ 4
* On 1955-8 350 c.c. “Bullets” the compression ratio is 7-25/1. Other com-
pression ratios are also available. 1958 “350 Clipper”: 6-75/1.
put them on or remove them it is advisable to insert small strips of sheet-
metal, about £ in. wide by 2 in. long, which are placed in the manner
shown by Fig. 70. Be most careful to note the order in which the rings
are removed to ensure correct replacement. When fitting piston rings,
thoroughly clean the grooves into which they fit, as any deposit left at the
back of new rings forces them out and makes them too tight a fit. Paraífin
usually loosens stuck piston rings.
When renewing piston rings, always fit rings supplied by The Enfield
Cycle Company, Ltd., or one of their approved dealers. Piston rings are
made to extremely fine limits and on new engines have a side clearance of
0-003 in. in their grooves. Never attempt to fit oversize rings to compen-
sate for wear unless an oversize piston and a rebore are necessary. Pistons
0-020 in. and 0-040 in. oversize, with similar oversize rings to suit, arc
The gap for all new piston rings, tested in an unworn part (the top or
bottom) of the bore, on Royal Enfield engines should be 0-011 in.-0-015 in.
It is advisable when it is necessary to remove the piston to check the gaps
of all three piston rings, using suitable feeler gauges. Renew any ring
whose gap exceeds 7 in. (0-006 in.). If new standard or oversize rings
are fitted, check their gaps before fitting them to the piston. When check-
Ing the gaps, insert each piston ring into an unworn part of the cylinder
bore and slide up the piston afterwards so that its crown contacts and
squares up the ring.
Scrutinize the ends of each ring. If they are bright, the ring gap is too
small; 1f, on the other hand, they are heavily coated with carbon, the
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This method (see text) can also be used for fitting rings. Note the slotted scraper
ring below the two compression rings. The top ring is chromium-plated.
gap is probably excessive. Should the gap of a ring be less than 0-008 in.,
clamp the ring between two wooden blocks in a vice and file one of the
diagonal ends slightly. If a new ring is found to be rather a tight fit in its
groove, rub down one side of the ring on a sheet of carborundum paper
laid flat on a piece of plate-glass. The slotted scraper ring (see Fig. 70)
fitted to Royal Enfield pistons can be fitted either way up. All three rings
should be assembled, using the safe method shown in Fig. 70. A final word
of good advice: if engine compression is good and the piston is doing its
Job well, leave the piston rings alone.
Decarbonizing the Cylinder Head. Carbon forms less readily on smooth
surfaces; therefore always decarbonize thoroughly. Remove all carbon
deposits from the cylinder head with a proprietary scraper, a blunt knife,
or a blunt screwdriver. Be careful not to scratch deeply the combustion
chamber, especially where the light-alloy head of a “Bullet” engine is
concerned. The author finds that a small electrical screwdriver is excellent
for decarbonizing the curved walls of the combustion chamber. To avoid
damaging the valve seats in the head, always first insert the valves in thetr
uides. a
> Remove all traces of carbon from the interior surfaces and do not forget
the sparking plug hole and the exhaust port(s). If a curved rifler 1s se
to clean up the port channels, be particularly careful not to allow tne
pointed end of the rifler to scratch the valve seats. Carbon deposits having
been removed, it is permissible, though not really necessary, to polish a
cast-iron type head with fine emery cloth, but do this before removing the
valves, and afterwards clean all abrasive particles away with paraffin.
Also scrape all carbon deposits from the heads of the valves.
With an aluminium-alloy head fitted to a “Bullet” engine, never use
emery cloth or any other abrasive to clean the combustion chamber, and
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in no circumstances attempt to remove carbon by immersing the head in a
hot caustic-soda or potash solution. Results will be disastrous.
Decarbonizing the Piston. With the comparatively soft aluminium-
alloy piston, be careful when removing the carbon. Do not use emery cloth,
but only a blunt knife, a proprietary scraper, or a blunt screwdriver. Do
not attempt to remove carbon from the piston skirt or the lands between
the rings. A little carbon is sometimes deposited on the inside of the piston,
and this should be carefully scraped off. If a screwdriver is used, be
careful not to allow the screwdriver shank to bump against the piston skirt.
Inspect the piston-ring grooves for carbon deposits; scrape any deposits
off, using a proprietary scraper or a home-made tool such as that shown
in Fig. 71. Do not forget to scrape carbon off the backs of the rings.
Having decarbonized the piston and rings, wash them thoroughly in clean
paraffin. Refit the rings by slipping them over the piston, using preferably
the method shown in Fig. 70.
Testing Big- and Small-end Bearings. When the piston is removed the
opportunity should always be taken of ascertaining whether any serious
wear has developed in the big-and small-end bearings of the connecting-
rod. The assembly is shown in Fig. 63. Appropriate instructions are on
pages 136-7.
T'o Remove the Valves. As has been stated on page 107, the valves should
be removed for inspection when decarbonizing, and if necessary both valves
should be ground-in. On the O.H.V. singles the valves are, of course.
housed in the cylinder head, the removal of which has already been dealt
with. Split collets are used for valve-spring anchorage, and hardened
end-caps are fitted to both valve stems (see Fig. 72). The tools shown in
Fig. 73 are necessary for removing and grinding-in the valves. These
1. Split collet 6. Exhaust valve
2, Outer collar for valve spring 7. Inlet valve
3. Inner valve Spring 8. Valve stem end-cap
4. Outer valve spring 9. Exhaust rockers
>. Valve-spring inner collar 10. Inlet rockers
(The Enfield Cycle Co., Ltd.)
ogg items can be obtained from any reputable accessory firm (see
page 88).
Before attempting to remove the valves it is advisable first to remove the
hardened end-cap 8 (Fig. 72) from each valve stem. Often the end-cap
becomes stuck on the valve stem, especially in the case of the exhaust
valve. To remove a stuck end-cap, prise it off with a screwdriver, or
alternatively grip the cap in a vice and pull the head away.
With the cylinder head stripped of the overhead rockers, rocker-
bearing caps, and valve stem end-caps, remove each valve in the following
manner, Place the forked end of the valve-spring compressor squarely
on the valve-spring outer collar and the pointed end of the screw in the
centre of the valve head. Then turn the tommy bar clockwise until the
valve-spring is compressed sufficiently to enable the split collet to be
removed. These split collets often become stuck and a sharp tap should
be delivered on the forked end of the valve-spring compressor. It should
—— a
never be necessary to apply excessive force to compress the springs.
When the collet is removed the duplex valve-spring and ıts upper collar
can be withdrawn, and the valve pulled away from its guide. If a valve
does not slide easily through the valve guide, remove any slight burrs on
the end of the valve stem with a carborundum stone, otherwise there is
some risk of damaging the valve guide. The inlet and exhaust valves are
not interchangeable, having different size stems and different grade steel.
Above is shown a sturdy valve-spring compressor and below a suction-type
valve grinding tool,
Keep all split collets, collars, and springs paired up with the respective
Grinding-in the Valves. Should an inspection of the valves reveal
pitting of the valve faces or seats, the valves will have to be ground-in.
Deal with each valve in the following manner. Clean both the valve face
and its seat in the cylinder head. Smear with a piece of rag or the finger
tip, a thin film of fine grinding paste (coarse at first if dealing with a valve
and seat in poor condition) on the valve face; replace the valve in its guide
minus the valve spring.
When using the valve grinding tool shown in Fig. 73, 1t 1s advisable to
moisten the suction pad. Only a light pressure on the tool 1s required and
care must be taken not to rock the valve, particularly if the valve guide 1s
somewhat worn. Rotate the valve about a third of a turn in one direction
and then an equal amount in the opposite direction, pausing every few
oscillations to raise the valve from its seat and turn it one-third to a
quarter of a revolution. Cease grinding-in when no “cut” can be felt (and
the valve begins to “sing”) and put some more paste on the bevelled edge
of the valve face if, after cleaning the valve in paraffin, some pitting is
still visible.
Continue grinding-in until both the valve face and seat have a matt
metallic surface uniformly over an appreciable depth (line contact is not
really sufficient) and there are no pit marks left after wiping the paste off.
Excessive grinding-in after a good seating has been effected eventually
leads to the valves becoming “pocketed,” which causes a considerable
decline in power output. Badly pitted valves or seats require to be
refaced by a competent mechanic.
After grinding-in the inlet and exhaust valves, wipe both the valves and
their seats thoroughly clean with a paraffin- or petrol-soaked rag to
ensure that there 1s absolutely no trace of any abrasive left. Examine the
valve guides for wear and renew if much play exists, otherwise slow-running
will become difficult. Often a valve stem wears more than its guide does,
and a distinct shoulder 1s felt near the neck of the valve. In this case fitting
a new valve (which must be ground-in) will probably remedy slackness
without fitting a new valve guide. Also renew the valve springs if weak.
Refitting the Valves. After grinding-in the valves you should reassemble
them in the correct positions in the cylinder head.
On all engines do not forget to replace the hardened valve stem end-
caps. Before replacing the valve springs, check that they have not lost
their tension, if possible comparing them with a new spring. Loss of
tension, due mainly to heat, sometimes occurs after several thousand
miles, and the free length of the valve springs is reduced. This necessitates
renewal and where such renewal 1s, or soon will be, required, it is obviously
wise to effect valve-spring renewal during decarbonizing procedure.
Smear the valve stems with oil and replace them in their guides. Then
refit the valve springs and outer collars, being careful not to mix up the
inlet and exhaust components. Next compress each valve spring and
refit the split collet, making certain that 1t “beds down” properly. The
application of a little grease to the inside of a split-collet enables it to
stick on the valve stem until the duplex spring 1s released, and thereby
facilitates reassembly. To ensure the split collet bedding down, hold a
box spanner over the outer collar and tap sharply. Do not forget to replace
the valve stem end-caps.
After Reassembly. It is an excellent plan to test the seats by pouring
some petrol into the ports and watching for leakage past the valves.
Petrol should not creep past the valves until after a considerable time has
elapsed. If it does, then this is sure proof that the valves have not been
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sufficiently ground-in and the remedy is (horrible thought!) to remove and
continue grinding-in. The ultimate test of good valve seating is engine
Replacing the Piston. Fit a new circlip into one of the piston-boss
annular grooves, using a small pair of snipe-nose pliers; see that the
circlip beds down snugly and is fully expanded (a loose circlip can ruin
the bore). If the gudgeon-pin is not a push fit in the piston bosses (it
rarely is), it is a good plan to warm up the piston in a bowl of boiling
water before fitting it to the small-end of the connecting-rod.
With the crankcase mouth protected by a cloth and the piston held in
its normal position, start the gudgeon-pin into the piston-boss hole oppo-
site to where the circlip has been fitted. Before fitting the gudgeon-pin,
make sure that it is the correct way round (see page 116) and smear it
liberally with some clean engine oil. Then tap in the pin holding the
piston firmly on the opposite side when using a soft-nose hammer or
small mallet. If the gudgeon-pin is a tight fit, press the pin in, using the
tool shown in Fig. 69, or a proprietary tool such as the Terry. As soon as
the gudgeon-pin contacts the circlip already fitted, fit a new circlip on the
other side.
To Replace the Cylinder Barrel (1946-55 Models G, J, J2; 1956-7
350 c.c. ““Clippers’’). The following procedure is recommended—
1. Check that the joint faces of the cylinder barrel and the crankcase
are scrupulously clean (see page 115) and fit a new cylinder-base washer
(21, Fig. 65) to the crankcase face, after smearing it lightly with some joint-
ing compound. Make absolutely sure that the small hole in the base washer
registers exactly with the oil-feed hole leading to the rear of the cylinder
2. Turn the engine over slowly so that the piston is just past B.D.C.
3. Smear the piston (especially the rings) and the bore of the cylinder
barrel with some clean engine oil, and space the ring gaps so that they are
at 120 degrees to each other. With a split-skirt piston, see that no gap is in
the immediate vicinity of the split in the skirt.
4. Holding the cylinder barrel vertically over the crankcase studs and
piston, with one hand, with the other one offer up the piston to the barrel
mouth. If difficulty is experienced in holding the piston and barrel steady,
it is best to obtain assistance or to tie up the barrel to the frame top-tube
with some stout string. Keep the barrel and piston absolutely square to
cach other and squeeze the rings by hand or with a proprietary metal
strap (without disturbing the ring-gap position) as the piston slowly enters
the bore. If a ring sticks, use no force, or ring breakage will result.
5. When the cylinder barrel has bedded right down on the base washer,
turn the engine over slowly to verify that the piston 1s quite free.
6. Fit and tighten evenly and in a diagonal order the five nuts (19,
Fig. 65) securing the cylinder base to the crankcase. One of these nuts
must be fitted to the stud inside the valve chest (see Fig. 62).
7. Reconnect the exhaust-valve lifter control cable.
To Replace the Cylinder Barrel (1954-8 250 c.c. “‘Clippers’’). Follow the
previous instructions (sub-paragraphs 1-6) for 1956-7 350 c.c. “Clippers”
but disregard sub-paragraph 7 referring to the exhaust-valve lifter.
To Replace the Cylinder Barrel (1949-58 350 c.c., 500 c.c. “Bullets”:
1958 350 c.c. ““Clipper’’). Use the following procedure—
1. Follow the 1956-7 “Clipper” instructions (sub-paragraphs 1-5)
given on page 123.
2. Fit the in. nut and washer shown at 22 in Fig. 67 and tighten the
nut (over the tappet chest) firmly but not dead tight. Reserve final tighten-
ing until the cylinder head has been replaced.
3. Proceed immediately with the replacing of the cylinder head (page
126), so that the sleeve nuts 18 on the five long crankcase-studs 19, securing
the head and barrel, can be firmly tightened down.
Assembling Cylinder Head and Rocker-box (1946-55 Medels G, J, J2;
1956-7 350 c.c. *“Clippers’’). Referring to Fig. 65 assemble the head and
overhead-valve mechanism in the following manner—
I. Check that the joint faces of the cylinder head and cylinder barrel
are absolutely clean, and turn the engine so that the piston is at T.D.C.
with both tappets right down.
2. To avoid oil leakage it is important to see that each push-rod cover-
tube joint (see Fig. 74) 1s perfect. Two metal ferrules 23 (Fig. 65) are
screwed into the bottom face of the cylinder head and mate with two
female Hallite washers 22 located in the push-rod holes on the upper face
of the cylinder barrel. It is advisable to renew both washers and coat their
sides with some gold size or shellac.
3. Renew the copper gasket 16. If the old gasket is in good condition
and you decide to fit it to the cylinder-barrel spigot, first anneal it by heat-
ing it to a red heat and then plunging it into cold water. Before fitting
the cylinder-head gasket to the barrel-face, smear both its sides with
a thin film of jointing compound.
4. Replace the cylinder head (with valves fitted) on the cylinder barrel
and fit the four in. nuts and washers 13 (sleeve nuts only on 250 c.c.
Clippers”) to the inverted cylinder-head studs 14.
>. Tighten down the four cylinder-head securing nuts evenly, firmly,
and in a diagonal order, to prevent the risk of head distortion. After
fitting new Hallite washers to the push-rod cover-tube joints always apply
pressure first of all to the two head-securing nuts on the timing side. This
will compress the Hallite washers and bring even pressure to bear on the
copper gasket. Further final tightening of the four cylinder-head securing
nuts will be necessary when engine assembly 1s complete and the engine
has been warmed up.
6. Replace (if previously removed) in its original position the lower
one-piece bearing caps 11, after checking that the oil-feed holes for the
rocker shafts are unobstructed. Also fit and tighten the central stud 10.
РОО РОО Ооо ge am gE EZ Ea E
|| я
Not applicable to “Bullet” and 1958 350c.c. “Clipper” models.
(The Enfield Cycle Co., Ltd.)
Check that both valve stem end-caps (8, Fig. 72) are in position and tap
them to ensure their being bedded down squarely.
7. Oil both ends of the push-rods 12, and fit the rods (the exhaust rod
has a collar) in their correct positions (with their adjustable ends at the
bottom); also lay the overhead-rocker shafts (see Fig. 72) 1n their respec-
tive lower bearing-caps, with the ball ends of the inner rocker-arms
engaging the inlet and exhaust push-rod cupped upper-ends. Oil both
rocker shafts liberally before assembly.
8. Fit the upper rocker-bearing caps 8, 9, (in their original positions)
and fit and tighten evenly, firmly, and diagonally the eight } in. nuts and
washers 7. Make sure that the upper and lower bearing-caps are truly
aligned, and after tightening down the cap nuts verify that both rocker
shafts move freely; if stiff, tap the end of each shaft smartly with a hammer.
9. Adjust both tappets as described on page 104 so that there is an inlet
and exhaust valve clearance of 0-002 in. and 0-004 in. respectively. Also
check the exhaust-valve lifter adjustment (see page 105).
10. Fit the oil-sealing gasket 6 (renew unless intact) and replace the
rocker-box cover 4, securing it with the central nut and washer 5. Also
replace the tappet-chest cover and washer 17.
11. Reconnect the oil-feed pipe 1 to the rocker-box and crankcase, and
tighten the two umion nuts 2, 3 very securely. Before replacing the pipe
blow through it to make sure it 1s unobstructed.
12. Kick the engine over quickly several times to circulate oil and to
ascertain that everything 1s satisfactory. Also fit the sparking plug so as to
blank off the plug hole. It is assumed that the plug has been cleaned and
checked for correct gap (see pages 93-3).
13. Proceed with the final assembly of the engine, exhaust system,
petrol tank, etc., as described on page 128.
Assembling Cylinder Head and Rocker-box (1954-8 250 c.c. “Clippers””).
Assemble the components exactly as just described for the 350 c.c. “Clip-
pers.” When replacing the two push-rods, be careful not to mix them up.
[t 1s assumed that you have marked them for identification (see page 111).
When adjusting the tappets, set them so that the clearance for both valves
1s nil (see page 104).
Assembling Cylinder Head and Rocker-box (1949-58 350 c.c., 500 c.c.
“Bullets”; 1958 350 c.c. ‘“Clipper’’). Referring to Figs. 66, 67, assemble
the head and overhead valve mechanism as follows—
1. Check the joint faces of the cylinder head and barrel for absolute
cleanliness, and turn the engine so that the piston is at T.D.C. with both
tappets right down.
2. Fit a new copper and asbestos gasket 23 to the cylinder-barrel face,
after applying some jointing compound to both sides of the gasket. Should
you replace the old gasket, anneal it before fitting it (see page 124, sub-
paragraph 3).
3. Replace the cylinder head (complete with valves) vertically on to the
cylinder barrel, and fit the four long sleeve-nuts, washers 18 to the crank-
case studs 19 projecting right into the rocker-boxes. Also fit the nut
and washer to the crankcase stud projecting from the near-side of the
cylinder head close to the sparking-plug hole. Fit also the nut and
washer 20 to the cylinder-barrel stud protruding from the off-side of the
cylinder head. Tighten down firmly all six nuts, being careful to tighten
them evenly and in a diagonal sequence to avoid the risk of causing
4. Tighten down firmly the § in. nut 22 (above the tappet chest), fitted
during the replacement of the cylinder barrel (see page 124, sub-paragraph
2). It is advisable to check all seven nuts again for tightness after warming
up the engine (see page 128). | |
5. Fit the two lower bearing-caps 16 for the overhead rockers, 1n their
original positions, after first verifying that their oil-feed holes are clear.
Also check that both valve stem end-caps (8, Fig. 72) are 1n position;
tap them to ensure that they are squarely bedded down.
6. Replace in their correct positions the inlet and exhaust push-rods 17.
Before doing so, oil both ends of each rod. Do not forget that the inlet
rod is the shorter of the two and that the adjustable ends must face down-
wards. Also lay the two overhead-rocker shafts (see Fig. 72) in their
respective lower bearing-caps, with the ball ends of the inner rocker-arms
engaging the cupped upper-ends of the inlet and exhaust push-rods. Before
assembling the rockers, oil both shafts liberally. |
7. Fit in their original positions the two upper bearing-caps 15, and
afterwards fit the eight 1 in. nuts and washers 14 securing both rocker-
housing assemblies to the cylinder head. Firmly, progressively, and in a
diagonal order, tighten down the eight cap-securing nuts. Be quite sure
before tightening down each pair of bearing caps that the two caps are ın
perfect alignment. After tightening is completed, check that both over-
head-rocker shafts are able to move quite freely; if stiff, tap the end of
each shaft sharply with a hammer. |
8. Adjust the inlet and exhaust tappets as described on page 104 so that
both valves have a clearance of nil. Afterwards replace the tappet-chest
washer and cover on the chest (which is integral with the crankcase).
9. Fit the decompressor unit 13 to the cylinder head, not omitting to
replace the copper washer between the head and the body of the unit.
Reconnect the control cable to the handlebars and adjust for backlash
(see page 106). |
10. Replace the inlet and exhaust rocker-box covers 9, 10, together with
their oil-sealing gaskets 26. Unless intact, renew these gaskets. The appli-
cation of some jointing compound is desirable. Secure each rocker-box
cover with three long sleeve nuts 11 and one short sleeve nut 12. "Ihe cor-
rect position for the shorter nut is referred to on page 112, sub-paragraph 4.
11. Reconnect the two-way oil-feed pipe 6 to the crankcase and the
separate rocker-boxes; tighten firmly the union nut 7 securing the pipe
to the crankcase, and the two union-screws 8 (with washers) securing
the banjo ends of the composite pipe to the rocker-boxes.
12. Turn the engine over smartly several times with the kick-starter to
check that everything is in order and to circulate oil. Afterwards blank
off the sparking-plug hole by fitting the plug. It is assumed to have been
cleaned and correctly gapped (see pages 93-9).
13. Complete the assembly of the engine, exhaust system, petrol tank,
etc. in accordance with the appropriate instructions given on page 128.
Final Engine Assembly (All Models). Reconnect the h.t. lead to the
sparking plug, after checking that its rubber insulation is sound. Fit a
new copper washer if the old washer is badly flattened. On the 1956-8
350 c.c. “Clippers” and all “Bullets” models, reconnect the engine steady
stay and tighten the nuts at both ends very tightly. On no account should
these nuts be firmly tightened before finally bolting down the cylinder head.
If not already done, clean and inspect the carburettor (see pages 30-1).
Ease the throttle and air slides into the mixing chamber of the assembled
carburettor, and fit the carburettor to the inlet-port face, after fitting a
new flange-washer; the addition of some jointing compound is beneficial.
Before replacing the carburettor, check its flange for truth (see page 31).
Tighten down firmly and evenly both carburettor-flange securing nuts,
but avoid excessive tightening, as this sometimes distorts the carburettor
body slightly and causes the throttle slide to stick. If the slide does stick,
case off the two nuts a fraction.
If an air filter is fitted, clean it (see page 34) and reconnect it to the
carburettor air-intake. Two types of connexion are used (see sub-para-
eraphs 3, 1, pages 109, 111).
Replace as a unit the exhaust pipe and silencer (duplicated on 1946-35
Model J2), and if you have to tap the pipe home into the exhaust port,
be most careful not to dent it at the bend. Tighten the nuts securing the
exhaust system to the frame very securely. If the exhaust pipe is very
sooty, it 15 a good plan before fitting the pipe and silencer to stand the
unit upright, with the silencer-end plugged, and pour some paraflin
through the other end, using a funnel. This will loosen most of the soot
and carbon, and on starting the engine, the exhaust gases will do the rest.
Rechecking Engine Nuts for Tightmess. Before replacing the petrol
tank on 1949-58 “Bullet” models it is advisable to run up the engine and
recheck, and if necessary tighten, all cylinder barrel and head securing-
nuts. Some nuts, particularly the sleeve nuts inside the rocker-boxes, are
not accessible when the petrol tank is replaced. It is suggested that a small
auxiliary petrol-tank be temporarily connected to the carburettor for
warming-up purposes and that the rocker-box covers be removed when the
engine is quite hot. When checking the above-mentioned nuts, it is
a good plan to check for tightness all other external nuts, especially
the nuts securing the overhead rocker-bearing caps, oil and petrol pipe
unions, etc.
On the 1946-55 Models G, J, J2 and all “Clipper” models the cylinder
head and barrel nuts, being below the head, are fully accessible, and
therefore rechecking of the nuts can be done after fitting the petrol tank as
described on the opposite page.
| Having rechecked engine nuts tor tightness with the engine warmed up,
it is desirable to recheck the tappet adjustment (see page 104) at a con-
venient opportunity when the engine is cold.
Replacing the Petrol Tank. On the 1946-55 Models G, J, J2 a rubber pad
is on the top of each of the tour tank-supports. Position the petrol tank,
and insert from below the four steel bolts, each having one rubber pad and
2 steel washer fitted as shown in Fig. 64. As mentioned on page 103, renew
reasonably tightly.
On the 1949-58 “Clipper
| fitted (in this order) over
the rubber pads if perished or damaged. Tighten all four bolts evenly and
and “Bullet” models, position the petrol
tank and replace and tighten the two transverse bolts, one at the front and
one at the rear. See that the distance tube and rubber buffer-sleeve are
the front transverse bolt before the bolt 1s
| inserted, also check that all washers are fitted in their correct positions.
timing they will automatic
mended by the engine manu
Ignition Timing. Some motor-cyclists imagine that by advancing the
ally obtain greater speed. The timing recom-
facturers is the maximum advance permissible.
A further advance in the timing submits the big-end bearing to undue
stresses and spoils the flexibility of the engine; it is also likely to cause
some spitting-back through the carburettor. Always employ the correct
ignition timings which are given in Table Vl.
If for a reason a Lucas ‘“Magdyno,” a Lucas SR-1 magneto (1956-5
“*Bullets”), or a Lucas or Miller contact-breaker (250, 3350 c.c. coil-
ignition ‘“Clippers’’) 1s
freed or extracted from its
removed (see page 103), or the driving pinion Is
tapered shaft, it is necessary 10 retime the
ignition. This should be done as described on pages 130-4.
Royal Enfield Engine
Maximum Ignition-Advance Permitted
1946-54 Model G
1946-8 Model J
1946-55 Model J2
1949-55 350 Bullet”
1953-5 “S00 Bullet”
1956-8 “350 Bullet”
1956-8 “500 Bullet”
1954-8 “250 Clipper”
1956-7 “350 Clipper”
1958 350 Clipper”
— EF
advance mechanism.
$ in. before T.D.C. (lever fully advanced)
# in. before T.D.C. (lever fully advanced)
3. in. before T.D.C. (ever fully advanced)
1 in. before T.D.C. (lever fully advanced)
3. in. before T.D.C. (lever fully advanced)
dy in.- in. before T.D.C. (ALA. fully advanced)
3 in. in. before T.D.C. (ALA. fully advanced)
4; in. before T.D.C. (A.L.A. fully retarded)
$ in. before T.D.C. (lever fully advanced)
#Æ in.—# in. before T.D.C. (A.L.A. fully advanced)
Note: In the above table, “Jever” refers, of course, to the ignition lever on
the handlebars, and “A.LA.” is an abbreviation for automatic-1gnition-
he fenton tring. (All Lucas “Magdyno” Models). Before checking
ing, or retiming the ignition, always clean the c
fully open, is 0.0 ane check that the gap between chem, with the contacts
open, -012-0-015 in. (see pages 96-7). An incorrect gap afl
the ming to some extent. It is assumed here that the “Mandyno” is
n: if it is not, attend to this (see page 103). It is, in
$ d to tl e | , in any case,
assumed that the “Magdyno” driving pinion has been removed with
the extractor referred to on page 103.
urn the engine slowly forward until the pi |
| wly piston 1s at the to
compression stroke, ho both valves fully closed. Next move ignition
ev e handlebars outwards to the fully advanced it]
it in this position until retiming is compl ’ ео ответе in
о ted. See that the stop- |
the magneto cam-plate 1s in the end ih > plate is not
en of the slot and that the plate 1
sticking. If the control lever is slack, tighten the lever que beto: oro.
ceeding further. aE
Turn the engine slowly backwards (b
| y means of the rear wheel wit
third > top gear engaged) until the piston has descended a distance below
ID. DT nde cxacty to the maximum ignition-advance (see
rue T.D.C., where the cylinder head h
removed, use a simply-made T.D.C. indic ) y of an old
ed, .D.C. ator. Screw the body of Id
sparking plug into the plug hole. Then inse | ok wire, or th
| t a piece of thick wi hi
rod, bent over at one end for satet h the | tre of the
, y, through the hole in the centre of th
plug body. Then mark with some red adhesi h with a
| | vith ve plastic, or scratch wi
thin Ihe a nick on the wire immediately above the top of the hole bea
S © t y rocking the crank produces no piston movement. |
e © another mark 1 ID. or whatever is the correct ignition-advance)
, and when turning the engine backward
the correct piston position for timin de do COUPS
€ , allow the second mark
the position of the first (T.D.C.) m. nder head be
.D.C.) mark. Should the cylinder head
removed for decarbonizing, the best method 1 i oht-edge a
, od is to lay a straight-ed
the top of the barrel and take vertical measurement with a steel rule This
gives a very precise timing.
ome owners prefer to retime the ignition by taki
| ng degr -
ments of crankshaft rotation, using a degree disc but this is puit un
necessary for normal purposes. | Te
aving obtained the correct position of the pi
| corr iston when th
haft by hand pi e the ‘nie lever fully advanced turn the maghcto
in its normal direction of rotation) so th h
the contact-breaker are just beginni Rod of deter:
e einning to open; the best method of deter
mining the point at which the contacts “break” 1 | mall slip
: | eak” is to insert a small sli
о! thin cellophane or tissue-paper between the contacts and gently ll on
act-breaker cam is slowly turned; immediately the slip 1
Te OP OA the magneto shaft to which the cam is fitted. Replace
the = agdyno” driving pinion on the tapered end of the magneto shaft
, being careful not to turn the engine, tap it home lightly, using a box
spanner and light hammer to direct even pressure ON the pinion boss. Lock
htening the lock-nut. When doing
the pinion to the shaft by fitting and tig
and lock the rear wheel so as to
this, it is advisable to engage a geal
prevent the engine turning. Before replacing the timing-Case Cover and
washer (see page 136), it 1s advisable to recheck the ignition timing.
Timing the Ignition (1956-8
1956-8 “Bullets” with a Lucas SR-1 rotating-magnet magnet (
58) have an automatic-ignition-advance (A.LA.) device into which the
magneto driving-pinion is built. The pinion is mounted on a smooth taper
on the magneto shaft and is secured by a nut (R.H. thread). When the
engine is stationary the A.L.A. device automatically keeps the ignition fully
Before checking the ignition timing or retiming the ignition, always
clean the contacts (if necessary) and check, and if necessary adjust, the
gap (0-010 in.—0-012 in.) between them, with the contacts at maximum
break. It is assumed here that the magneto, 1f previously removed, has
been replaced, but that the timing cover has been removed (see page 134)
and the driving pinion (with embodied A.LA. device) extracted by un-
screwing the nut which pulls the pinion off.
Turn the engine slowly forward until the piston is exactly at the top of
the compression stroke, with both valves fully closed. Next rotate the
two halves of the A.LA. coupling relatively to each other, against the
springs (i.e., into the fully-advanced position); with a piece of wire hold
it in this position.
Now turn the engine slowly backward (by means of the rear wheel with
third or top gear engaged) until the piston has moved down from T.D.C. a
distance corresponding exactly to the maximum ignition-advance per-
mitted and specified in Table VI. Insert a piece of wire through the spark-
ing plug hole (as described on page 130) for finding the true T.D.C. position
and the point of maximum ignition-advance.
Having obtained the piston position corresponding to the maker's
timing, turn the magneto shaft and cam forward until the contacts of the
‘по the method referred to on
contact-breaker are beginning to break, using
A. device, tap them home
page 130. Then replace the driving pinionandA.l.
(see page 130), and afterwards firmly retighten the nut, being careful not
to turn the engine when doing so. Then remove the piece of wire locking
the A.LA. device. Finally recheck the ignition timing (with the timing
cover and washer removed) Dy removing the cover (see Fig. 58) from the
magneto and holding the rotor in the fully-advanced position. If timing
is correct, replace the timing cover and washer.
250 c.c. “Clipper” Ignition Timing (1954-8). A centrifugal type autos
matic-ignition-advance (А.Т.А.) device is incorporated at the back of the
Miller or Lucas contact-breaker, having a range of approximately 123
— _ —
- pun J ELE ПО hl ar a THT = We JA E am
degrees on the half-speed shaft, corresponding to 25 degrees on the engine
shaft. The maximum permitted ignition-advance is 30 degrees, so that,
with the A.I.A. fully retarded, the contacts must open when the piston is
5 degrees or about 17 in. before T.D.C.
Timing the Ignition (250 c.c. “Clippers” with Miller Equipment). Оп
1954 to early 1955 coil-ignition models it is not necessary to remove the
timing cover and contact-breaker driving pinion to retime the ignition,
as the contact-breaker cam can be moved as required on its shaft. The
following procedure 1s necessary.
Switch off the ignition and after cleaning the contacts (if necessary)
check and if necessary adjust the gap (0-015 in.—0-018 in.) between the
contacts of the contact-breaker as described on page 99. Unscrew and
remove the centre screw which secures the cam to the contact-breaker
shaft. Next free the cam by screwing a -% in. B.S.F. bolt into the threaded
hole. Slacken the two small screws securing the contact-breaker base
plate, and adjust the plate so that it is centrally positioned in its slots.
Afterwards tighten both screws.
Jack the motor-cycle up on its stand (use packing if necessary to raise
the rear wheel clear of the ground). Engage third or top gear and slowly
rotate the engine by turning the rear wheel until the piston 1s below
T.D.C. (on the compression stroke) a distance exactly equal to the maxi-
mum ignition-advance permitted (see Table VI). To find the true T.D.C.
and subsequent timing position, use a piece of thick wire or thin rod
inserted as described on page 130.
Now switch on the ignition and rotate the cam clockwise (as viewed from
the near-side) until the ignition warning-lamp lights up. Continue slowly
to rotate the cam clockwise until the lamp just goes out, indicating that the
contacts have just separated and broken the primary circuit. Secure the
cam to its shaft by delivering a sharp tap endwise, and lock in position by
firmly tightening the cam securing-screw. See that the engine is not turned
until the cam is firmly locked. Recheck the ignition timing by causing
the ignition warning-lamp to go out, and verifying the position of the piston
below T.D.C. when this happens.
Should the ignition timing be slightly out, correct by loosening the two
screws which secure the contact-breaker base-plate to its housing, and
turn the plate clockwise to retard the timing, or anti-clockwise to advance
it. An adjustment range of plus or minus about 6 degrees is provided by
the slots in the plate.
Timing Ignition (250, 350 c.c. “Clippers” with Lucas Equiment). On
late 1955-8 coil-ignition models it is necessary (if the driving pinion has
been removed) to replace the pinion after adjusting the timing so that it 15
approximately correct, and then to make a final precision adjustment by
slackening the clamping bolt and turning the contact-breaker housing as
— 2 ATT a
required; the housing 18 clamped on to the contact-breaker bracket which
is bolted to the top of the crankcase. |
If the contact-breaker drive has been dismantled, clamp the contact-
breaker housing so that the name on the cover is approximately horizontal.
Clean the contacts (if necessary) and then check and if necessary adjust
the gap (0-015 in.~0-018 п.) between them. Turn the engine forward
30° te 350 EC
: iming 1 bove, except
On 1953-8 500 c.c. “Bullet” engines the valve timing is as shown a
that the inlet valve opens 40 degrees before T.D.C. and closes 70 degrees after
until the piston is exactly af T.D.C. on the compression stroke, with both
valves closed. Then turn the engine slowly backwards (by means of the
rear wheel with third or top gear engaged) until the piston has descended a
distance exactly equal to the maximum ignition-advance (on full retard)
specified in Table VI. Insert a piece of wire or rod through the plug
hole as described on page 130, to find true T.D.C. and the subsequent
lower position for correct timing. Without moving the engine, turn the
contact-breaker shaft and cam until the contact-breaker points are
beginning to break (see notes on page 130).* Then replace the driving
* An alternative method of finding the exact moment of contact opening 1s
to switch on the ignition and observe the warning lamp or ammeter.
— — ——o ol
=" T= =
pinion on the shaft taper, and again check the maximum opening of the
contacts. Recheck the ignition timing and make the final close adjustment
by slackening the clamping bolt securing the contact-breaker housing and
rotating the housing slightly until the correct ignition-setting is obtained.
Finally replace the timing cover and washer.
The exhaust camwheel and flat-base tappet arc shown removed.
Valve Timing. The correct valve timing for all 1946-58 Royal Enfield
engines is shown diagrammatically in Fig. /5. Under no circumstances
attempt to alter this timing which has been determined by the Redditch
designers after much research and calculation. If for any reason you wish
to check the valve timing, using the crankshaft degree-disc method, note
that this must be done with a valve clearance of 0-005 in., except on the
1953-8 “Bullet” engines and the 1956-8 350 c.c. “Clipper” engines; here
the valve clearance should be 0-012 in. The valve clearances required for
normal running are those specified in Table IV on page 104.
To Remove Timing Cover (All Engines). Lay a drip-tray beneath the
engine to collect the engine oil which dramns off when the timing cover 1s
removed. Remove as a unit the exhaust pipe and silencer (duplicated on
Model J2). Now remove the nine small screws which secure the timing
cover to the timing case. Slacken off the screws evenly and be careful not
to lose the nine oil-sealing washers. Then carefully withdraw the timing
cover and its washer. If the cover is stifi, tap it gently with a mallet.
Removing and Replacing the Timing Gears. The removal of the timing
(The Enfield Cycle Co., Ltd.)
cover exposes the complete gear train (see Fig. 76) comprising the inlet
and exhaust camwheels (with integral cams), and the two intermediate
gears (for the magneto Or contact-breaker drive). All gears can readily
be removed if desired. But do not remove unnecessarily the worm-shatt
and integral lock-nut which secure the engine pinion. lo remove the
pinion trom the engine shaft, unscrew the worm-shaft, using service tool
(Part No. E5451) on the hexagon behind the worm; it has a left-hand
thread. Extract the pinion by inserting a flat chisel, or a similar tool,
behind the pinion and tapping the tool gently.
A dot system of marking the two camwheels is employed (see Fig. 77).
When replacing the timing gears, turn the engine so that the piston Is at
top-dead-centre and replace the exhaust camwheel so that its two dots
are exactly opposite to the two dots on the crankshaft pinion. Similarly
replace the inlet camwheel so that its single dot registers exactly with the
single dot on the exhaust camwheel. Valve timing must then be as indi-
cated in the timing diagram shown in Fig. 75, assuming that the tappet
clearances are adjusted correctly for timing (not normal running) purposes.
To Replace Timing Cover. When doing this, see that the joint washer 1s
located properly over the oil holes. It is not advisable to use jointing
compound, but both sides of the washer should be smeared with some
grease. Use a new washer unless the old one is perfect. Make sure that
the cork or rubber plug is positioned in the pump-worm hole; if damaged
in any way, renew the plug to ensure oil being fed to the big-end at the
correct pressure.
It is important to turn the engine slowly forward while replacing the
timing cover; this helps the pump worm to engage the pump spindle, and
thereby avoids the risk of damage occurring. Before fitting the timing
cover, clean the filter chamber with some clean engine oil, Tighten down
the nine screws evenly and firmly, and do not omit the nine oil-sealing
washers. After fitting the timing cover, check the functioning of the oil
pump by running-up the engine, removing the oil filler-cap, and observing
the flow of oil through the relief valve. Note that it may be several
minutes before the oil flows back in any quantity. Afterwards replace the
exhaust pipe(s) and silencer(s).
The bearings on the crankshaft and connecting-rod assembly (see Fig. 68)
are of robust design and provided you keep the oil tank topped-up with a
plentiful supply of oil, and change the oil regularly (see page 41), you are
unlikely to experience any bearing trouble for a very long period. Careless
driving tactics, however, have a considerable effect on the wear of engine
bearings. Avoid allowing the engine to labour with top gear engaged,
running on full bore for excessive periods, and being impatient during
the running-in period (see page 14).
The Small-end Bearing. The connecting-rod small-end (see Fig. 68) has
a carobronze bush, except on “Bullet” models where the small-end of the
RR 56 light-alloy connecting-rod is bored to give a direct bearing surface
for the large-diameter gudgeon-pin. After long usage, the eye of the
connecting-rod can be bored oversize to receive a bush, but this is rarely
With the engine cold, the fully-floating gudgeon-pin should be a free
working fit in the small-end bearing, and a push fit in the piston bosses.
When you have occasion to remove the cylinder barrel, insert the gudgeon-
pin in the small-end and check for any “rock” in the bearing. No appre-
ciable play is permissible.
—= — zz "НЕЕ — — -—
The Big-end Bearing. This comprises a hardened chrome-stecl bush
pressed into the big-end eye of the connecting-rod, and a mild-steel whitc-
metalled floating bush (see Fig. 68). When you remove the cylinder barrel,
check for play in the big-end bearing by firmly gripping the connecting-
rod, with the rod at B.D.C., and attempting to push-and-pull it downwards
and upwards, preferably with the oil film dispersed. A very slight degree
of “shake” 15 permissible, but there should be no marked up and down
movement. Under favourable circumstances the big-end bearing can be
expected to remain serviceable for up to 30,000-40,000 mules, but it 1s
impossible to specify any definite mileage.
The Main-shaft Bearings. On Models С, J, 12, “1954-7 Clippers,
heavy-duty caged-roller bearmgs are used for both main-shafts, the outer
| Aa AN
The above arrangement applies to all pre-1956
“Bullet” engines.
(The Enfield Cycle Ca, Ltd.)
races being shrunk into the crankcase and the rollers running direct on
the main-shafts. CL.
On early “Bullet” engines two ball bearings are provided on the driving
side and one single-row roller bearing on the timing side. The later
“Bullet” engines have one ball and one roller bearing on the driving side,
and a single-row caged-roller bearing on the timing side as shown 1n Fig.
78. On 1956-8 “Bullets,” however, the timing-side bearing comprises à
double-row roller bearing. A small degree of end-float is permissible, but
no appreciable up-and-down movement should exist on attempting to
“rock” the main-shafts up and down.
The Camwheel Bearings. The camwheels have internal bronze-bushes
running on fixed spindles in the timing case, and should last tor thousands
of miles without attention.
Renewing Engine Bearings. When the engine begins to run somewhat
roughly and inspection shows that there is appreciable “shake” in the
я нений O CTT TTT ,
main and big-end bearings, it is advisable to remove the cylinder, cylinder
barrel, “Magdyno” (or magneto or contact-breaker), the timing cover, Its
contents, etc, and remove the crankcase from the frame. This should then
be delivered or dispatched to the Enfield Cycle Co., Ltd., or to one of their
authorized repairers, so that new bearings can be fitted, and the crankcase
rebushed where necessary. Dismantling and rebuilding the crankshaft
assembly is a skilled job involving accurate alignment of the flywheels and
main-shafts, and the use of special tools and appliances; the work 1s
rather beyond the ability of the average motor-cyclist and is beyond
the scope of this maintenance handbook. Should you attempt this and
similar repair work, you are advised to obtain a copy of the appropriate
Workshop Maintenance Manual from an Enfield dealer.
To Remove the Crankcase Assembly (1946-55 Models G, J, J2). Firstly
remove the cylinder head and cylinder barrel as described on pages 109
and 114 respectively. Disconnect the h.t. cables to the Lucas “Magdyno.”
Place a drip-tray beneath the oil-bath chain case and remove the cover
from the chain case. To do this, remove the nut securing the near-side
footrest, detach the latter, also the rear-brake pedal, and pull the cover clear.
Remove the engine sprocket (splined to the drive shaft and secured by a
large lock-nut and washer), the primary chain, and the clutch sprocket.
To dismantle the clutch, unscrew the three clutch-spring pins and with-
draw the spring cap, the three springs, the distance tubes, the clutch front
plate, the outer retaining spring, and the assembly of driven and driving
plates. Now remove the large circlip and withdraw the clutch sprocket
from the clutch centre. To remove the clutch centre it is necessary to use
the Royal Enfield extractor (Part No. E5414). The clutch centre 1s
mounted on splines on the gearbox main-shaft and is secured by a nut
with right-hand thread. Remove the small screw which secures the rear
half of the oil-bath chain case to the gearbox securing bolts. Now withdraw
the rear half of the chain case.
Support the crankcase by inserting some Strong packing (€.g., a box)
beneath it, and then remove the bolts holding the engine to its mounting
plates. Finally ease the crankcase assembly carefully out of the frame
ready for further dismantling and bearing renewal.
Instructions for removing the timing gears and the Lucas “Magdyno”
are given on pages 134 and 103 respectively. Piston removal 1s dealt with
on page 115.
To Remove the Crankcase and Gearbox (1949-55 350 c.c. 500 с.с.
Bullets”). The crankcase and gearbox are bolted together and must be
removed as a single unit. First remove the cylinder head and cylinder
barrel as described on pages 111 and 114 respectively. Disconnect the
four h.t. leads to the Lucas “Magdyno.” Next lay a drip-tray below the Oll-
hath chain case and remove the cover; to do this, remove the single bolt
securing it. Now remove the engine sprocket, the primary chain, the
clutch assembly, and the oil-bath chain case rear hall.
An endless-type chain is provided, and it is therefore necessary to
remove the two sprockets and the chain simultaneously. The procedure
for removing the engine sprocket, the clutch assembly and the clutch
sprocket is the same as for Models G, J, J2 (see second paragraph in the
previous section). Remove the three nuts securing the rear half of the
oil-bath chain case to the crankcase, and withdraw the rear half of the
chain case. Remove the secondary chain.
Place a box or other suitable packing beneath the rear-fork pivot lug,
to support the machine, and insert additional packing beneath the crank-
case to remove its weight when freed from the frame. Remove the two
front engine-plates, and disconnect the stand spring and remove the centre
stand. Completely remove the attachment plates below the gearbox and
remove the stud securing these plates to the base of the frame seat-tube.
Remove the nuts holding the fixed half of the rear mudguard to the gear-
box. Finally pull the crankcase and gearbox forward and turn slightly
to the off-side until the unit is completely withdrawn.
For instructions on removing the timing gears and the Lucas “Magdyno,
see pages 135 and 103 respectively. Piston removal is referred to on page
115. |
To Remove Crankcase and Gearbox (1956-8 350 c.c., 500 cc. ‘““Bullets’’;
1958 350 c.c. “Clipper””). The crankcase and gearbox are bolted together;
remove as a unit. First disconnect the stop-tail lamp leads at the socket
provided, and remove the rear mudguard and the dualseat. “Then remove
the petrol tank as described on page 10s. Disconnect the horn and earth
wires from the rectifier and then proceed to remove the cylinder head and
cylinder barrel as described on pages 111 and 114 respectively.
Lay a drip-tray beneath the oil-bath chain case and remove the chain-
case cover after unscrewing its single securing-bolt. Remove the three
nuts holding the alternator to the lugs within the chain case and remove
the alternator stator: be careful with the three small distance-pieces.
Remove the large hexagon securing the rotor to its shaft and remove the
rotor. Next remove simultaneously the engine sprocket, the endless
primary chain, and the clutch sprocket. Appropriate instructions tor
doing this are those given in the section for removing the crankcase
assembly on Models С, J, J2 (see page 158). Remove the three nuts
securing the rear half of the chain case and withdraw the latter.
Remove the tools and the battery (see Fig. 34) from the container on
the near-side of the machine. Remove the guard for the secondary chain,
and also the short guard at the gearbox end; disconnect the spring link
and remove the secondary chain.
Allow the machine to rest on the centre stand, but insert a box or other
suitable packing beneath the crankcase to take its weight. Remove the
5. in. studs from the engine front mounting-plates, and also remove the
5. in. stud from below the gearbox. Loosen the + in. stud farther along,
and disconnect the spring for the centre stand. Now remove the off-side
footrest and carefully ease the engine and gearbox unit out of the frame
from the off-side. The removal of the piston and timing gears are dealt
with on pages 115 and 135 respectively.
To Remove the Crankcase and Gearbox (1956-7 350 c.c. ““Clippers’’).
Remove the cylinder head and cylinder barrel as described on pages 109
and 123 respectively. Disconnect the Lt. cables to the Lucas “Magdyno.”
Remove the footrests, the footrest rod, and the centre stand.
Place a drip-tray beneath the oil-bath chain case and remove the chain-
case cover. Then remove the engine sprocket, the primary chain, the
clutch sprocket, the rear halt of the chain case (see instructions on page
138 for Model G), and the secondary chain.
Insert some substantial packing beneath the crankcase and remove the
top and bottom bolts securing the rearmost points of the rear engine
plates to the frame. Remove the front engine-plate bolts and carefully
ease the crankcase out, complete with the gearbox and the rear engine-
plates. The removal of the piston “Magdyno,” and timing gears are dealt
with on pages 115, 103 and 135 respectively.
To Remove the Crankcase Assembly (1954-8 250 c.c. “Clippers””).
First remove the cylinder head and cylinder barrel as described on pages
111 and 114 respectively. Undo the adjuster nut from the rear of the
brake rod and allow the rear-brake pedal to drop down. Next remove the
footrest and disconnect the three Lt. electric leads; they are coloured (see
Figs. 52-3) to facilitate correct replacement.
Place a drip-tray beneath the oil-bath chain case and remove the cover
from the case. Now proceed with the dismantling of the clutch. Remove
the three spring-studs, washers and clutch springs. Remove the clutch
plates, the sprocket, and the short push-rod which has a flat head. Remove
the spring link and take off the primary chain. Removal of the spring link
is facilitated by removing the tensioning slipper (see Fig. 84) below the
chain lower-run. Remove the clutch centre, using the Royal Enfield
extractor (Part No. E5414). Remove the alternator rotor from the engine
near-side main-shaft, and extract the sprocket from the shaft. Thenremove
the rear half of the oil-bath chain case after removing the three socket
screws and locking washers.
With the machine on 1ts centre stand, and some strong packing inserted
under the crankcase to take its weight, remove the bolts from one front
engine-mounting plate and withdraw the plate. Remove both bolts from
the rear engine-mounting plate. Loosen the gearbox securing nuts so as
to permit some small movement of the rear engine-plate. Finally, cause
the crankcase carefully sideways and forwards until it clears the frame
and can be placed on the bench for attention. The removal of the timing
gears, the contact-breaker unit, and the piston are dealt with on pages
135, 103, 115 respectively.
The transmission comprises (front to rear): the primary chain, the clutch,
the gearbox, the secondary chain, and the cush-drive rear hub (dealt with
in the next section).
Clutch Control Adjustment. lo prevent clutch slip or drag (both serious
nuisances), it is essential always to keep the clutch correctly adjusted.
The clutch springs themselves are not
adjustable for tension. Sufficient free
movement (about + in.), however,
must be maintained in the clutch
control, otherwise the plates of the
multi-plate clutch (four plates on most
machines) will not be pressed firmly
against each other when the clutch
is engaged, and the consequent slip
will damage or ruin the cork or fabric
On a new machine, or where the plates
have had new inserts fitted, some initial
bedding-down of the inserts occurs; FIG, 739. CLUTCH CONTROL
this often results in the essential free ADJUSTMENT
movement in the clutch control being Applies to 1946-55 Models ©, 2, 32;
taken up during the first few hundred 1956-7 330 c.c. ‘Clippers.
miles. Thereafter, after covering about (The Enfield Cycle Co. Ltd.)
250 miles, and subsequently at intervals of about 1,000 miles, check the
adjustment of the clutch control as described in succeeding paragraphs.
_ Го Adjust the Clutch Control (1946-55 Models G, J, J2; 1956-7 350 c.c.
Clippers”). To adjust the direct-type of operating lever shown in Fig.
9, first detach the lever 1 from the control cable and hinge 1t back to
vive access to the adjuster screw 2 and the sleeve 3. The lever 1 should
have a free movement of about + in. To increase the movement, turn
the adjuster screw 2 anti-clockwise. To reduce the movement, turn it
clockwise. As may be observed in the sketch, no lock-nut is provided.
When the lever 1 is positioned, and the control lever is connected up, the
«crew 2 and the sleeve 3 are automatically locked by the lever. |
To Adjust the Clutch Control (1949-33 350 c.c., 500 c.c. ‘*Bullets™).
Referring to Fig. 80, first slacken the clamping screw 1. Next hold the
end of the operating lever 2, turning it with a slight pressure towards the | Late 1954-7 “Bullets” and 1958 350 c.c. “Clipper have an enclosed:
right. Then position the operating arm 3 as required until a free move- type clutch control with dual adjustment. Referring to Fig. 51, to adjusi
ment of about +; in. exists in the control cable after retightening the the clutch control, first remove the two metal-discs from the gearbox
Applies to 1949 to early 1954 350 c.c., 500 c.c. “Bullets.”
a 7 С; + т Lid. I . x :
(The Enfield Cycle Co ) Fi. 81. CLUTCH CONTROL ADJUSTMENIT
, В Late 1954-7 350 c.c., 500 c.c. “Bullets,” 1958 “350 Clipper.”
clamping SCrew 1. When making the clutch-control adjustment, it 15 a (The Enfield Cycle Co. Ltd.)
important to observe the following two points—
|. Position the arm 3 so that it is approximately square with the clutch
cable, disengaged. The length of the inner cable beneath the lever can be end-cover. Then effect any major adjustment necessary by slackening the
effectively adjusted by means of the adjusting screw 4 and the lock-nut >. lock-nut 1 (accessible through the lower inspection-hole) and with a
2. Position the arm 3 endwise on the operating worm 7 SO that 1ts screwdriver screwing the slotted adjuster-screw 2 inwards or outwards
ner face is about % in. from the small triangular oil-retaining cap ©. until there is a free movement of about À in. at the cable end of the clutch
Avoid a clearance exceeding ÿ In, otherwise there is a risk of the arm 3 operating-lever 3. You can check this movement through the upper
fouling the crank of the kick-starter pedal. inspection hole.
To compensate for stretch in the clutch operating-cable, or to make any
minor clutch-control adjustment (after effecting a major adjustment as
just described), loosen the lock-nut 4 and screw the adjuster screw S
(behind the oil filler-plug hole 6), by means of its hexagon, in or out us
To Adjust the Clutch Control (1954-8 350 c.c., S00 c.c. “*Bullets?”?; 1958
350 c.c. “Clipper””). On early 1954 “Bullets” an exposed-type clutch
operating-lever (Fig. 80) 1s provided; should a clutch-control adjustment
become necessary, effect this as for the 1949-53 “Bullets.”
To Adjust the Clutch Control (1954-8 250 c.c. ““Clippers’’). Referring
to Fig. 82, first disconnect the clutch operating-cable from the operating
lever 1. Next remove the inspection cover from the off-side of the gearbox
and move lever 1 (as shown in Fig. 82) so that the fork at the foot of the
operating-lever spindle clears the adjuster screw 3. ‘Then turn the adjuster
screw as required until a slight clearance (say, —; In.) exists between the
0 Пи =
Applies to 1954-8 250 c.c. “Clippers.”
(The Enfield Cycle Co,, Ltd.)
shoulders of the adjuster sleeve 4 and the fork 2, when the lever 1 18
reconnected to the clutch operating-cable. In this position the fork 2
automatically locks the adjuster screw 3.
therefore to keep the oil-bath chain case well topped-up (sec page 47)
The dismantling of the clutch assembly is dealt with in the section (sce
pages 140-1) covering the removal of the crankcase and gearbox.
As has been stated on page 141, no adjustment 1s provided for the clutch
spring pressure and /he the screws must a'ways be kept fully tightened
20 NT
| i
A TE ere)
ln AC ee
The above assembly applies to 350 c.c., 500 c.c. Buliets,” but the general layout
is similar on all models. On the 250 c.c. “Clippers,” however, there are only
two insert plates, and one of these comprises the ciutch sprocket.
(The Enfield Cycle Co., Lid.)
It persistent clutch slip develops, it is advisable to renew the clutch springs
15 well as the clutch inserts.
Adjustment of Neutral-finder Lever. A stop-sleeve limits the forward
To compensate for stretch of the clutch control-cable, or to make any
minor adjustment necessary (after making a major adjustment as Just
described), loosen the lock-nut 5 and then turn the adjuster screw 6 as
and downward travel of the lever (provided on all except the 250 c.c.
Clippers’). Should the lever fail to locate neutral, slacken the hexagon-
headed screw securing the sleeve, and turn the sleeve as required. This
adjusts the position of the neutral finder at the end of its travel, the sleeve
seing eccentric.
If the Clutch Slips. First of all check that the clutch-control adjustment
(see pages 141-4) is correct. If this is so, perhaps the plate inserts have
become worn flush with the plates or have become burnt. The remedy
here is to dismantle the clutch and have new inserts fitted to the plates.
Note that where cork inserts are used (i.e., most models except the 1956-3
“Bullets”) these inserts wear better when oil is present; 1t 1s advisable
Gear Control Adjustment. As the foot gear-change lever 1s mounted
directly on the gearbox, it is impossible for the gear control to get out of
idjustment. Should the gear-change lever, however, be positioned in-
conveniently relative to the off-side footrest, loosen the pin securing the
‘ever to the operating mechanism on the gearbox, withdraw the lever,
a = д == = == ey 2 leg." Wg "= ™ el marT O CE -— E AL = |. -
and replace it one serration higher or lower to enable gear changes to be
made smoothly without raising the foot from the footrest.
| iking fork operates all the gears
The Four-speed Gearbox. A single striking |
and it is therefore quite impossible to engage we gears roe plac:
r much wear has occurred. Wear Inside the geal
very slowly always provided that the gearbox is correctly lubricated (see
заре 47). If serious gearbox trouble does develop through neg ecto!
after a very big mileage, 1t 1 advisable to remove the complete gear ox
and have it overhauled by The Enfield Cycle Co., Ltd. (see Preface), 01
hy an authorized Royal Enfield repairer.
To Remove Gearbox (Models G, J, J2). Remove the oil-bath chain
case, the engine sprocket, the clutch, and the secondary € ans al any
tems obstructing gearbox removal. Then remove the gear p
hottom mounting-bolts and lift the gearbox out of the frame.
To Remove Gearbox (350 c.c., 500 c.c. “Bullets””). Remove 14° gear
hox and crankcase together (see page 139). Then remove the four + IN.
securing nuts and withdraw the gearbox from the crankcase.
To Remove Gearbox (330 c.c. ““Clippers’’). Remove the gearbox and
crankcase together (see page 140). Then separate the cran ease ane gear ох
Wi ‘rear ine- tively, 11 the €
bv removing the rear engine-plates. Alterna he ct
not been disturbed remove the oil-bath chain case, ne mon sprocket.
| | items which facılıtale rc
the clutch, the secondary chain, and any 1 !
À the gearbox. “Then remove the top and bottom bolts on which the gear
box is mounted in the rear engine-plates. Remove the off-side rear plate.
Now lift the gearbox out of the frame.
To Remove Gearbox (230 c.c. “Clippers””). Remove the oil-bath che? г
-ase, the engine sprocket, the alternator stator and rotor, the ou ch, nd
the secondary chain. Next remove the two —g IN. engine ° sa
vearbox top and bottom bolts, and lift the gearbox out ol the Нате.
Chain Lubrication. See instructions On pages 47-50.
Importance of Correct Chain Tension. Always keep the primary on
secondary chains correctly tensioned (Lin. and ÿ IN. whip respec ve y
A slack chain is apt to rattle and jump the sprockets, while an e e
tight chain is liable to damage the chain rollers and the pros с teeth.
To check the tension of the primary chain, remove the oil-bath chain ca:
cover or inspection cap where fitted.
1 Adi 5 J. J2; 1956-7 350 c.c.
mary Chain Adjustment (1946-55 Models G, J, Je;
Clippers" Slacken th: nuts on the top and bottom bolts holding the
gearbox to the engine rear mounting-plates; then pivot the gearbox as
required about the bottom bolt until the chain is tensioned so that there
is a total up-and-down free movement of about j in., measured al the
centre of the chain run (with the chain in its tightest position). Be carclui
to retighten the nuts on the gearbox very firmly, again recheck the primary-
chain tension, and check the tension of the secondary chain.
Primary Chain Adjustment (1949-58 350 c.c., 500 c.c. “Bullets :
1954-8 250 c.c. ““Clippers’’; 1958 350 c.c. “Clippers””). Remove the cover
pad FTW LT a TL RT OT TTR TRE "ИИ. srt. ee NTT т. =e Wh Fra hen ehr a
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The arrangement illustrated is used on all “Bullet” models and 250 С.С. “Clip-
pers”; no alternator is, of course, fitted to pre-1956 ‘“Bullets” with “*“Magdyno
lighting and ignition,
(The Enfield Cycle Co. Ltd)
‘rom the oil-bath chain case-(see pages 139 and 140) to expose the
duplex primary-chain and its curved slipper-type tensioner, shown in
Fig. 84. Then loosen the lock-nut 1 and turn the set-screw 2 clockwise or
anti-clockwise by means of its hexagon head until the slipper 3 tensions
the chain such that there is a total up-and-down free movement of about
L in., measured at the centre of the top run of the chain (with the chain
its tightest position). Afterwards tighten the lock-nut 1 securely, and
replace the cover on the oil-bath chain case.
Secondary Chain Adjustment (1946-55 Models G, J, J2). Always adjust
the tension of the secondary chain after making a primary chain adjust-
ment and when chain stretch increases whip beyond the specified limit.
To adjust the secondary chain, place the machine on its rear stand and
loosen both rear-wheel spindle nuts. Then after slackening the lock-nuts,
-— == = ° Rim oma rill o ls = un alike smd ar " =
ala " = == = - = =" — тонн = он = = = = Ев =
until the chain has a total up-
turn the set-screws 1n the rear-fork ends
the centre of the
and-down free movement of about + 1n., measured at
chain lower-run (with the chain in its tightest position).
it js most important when turning the set-screw adjusters to screw 1n
both set-screws exactly the same amount, to maintain the chains and wheels
in true alignment. If in any doubt as to the latter, check the alignment oi
the front and rear wheels as described on page 150. After making the
ESE aay,
dig Iv
(The Enfield Cycle Co., Ltd.)
he lock-nuts on both set-screws very firmiy,
required adjustment, retighten t
f the rear brake (see page 133).
and also check the adjustment O
Secondary Chain Adjustment (1949-58 350 c.c., £00 c.c. “Bullets”;
1954-8 250 c.c., 350 c.c. Clippers”). On all machines with “swinging
arm” rear suspension the tension of the secondary chain should be checked
with both wheels resting on the ground and the rider seated.
Referring to Fig. 85, to adjust the tension of the secondary chain,
<lacken both rear-wheel spindle nuts 1 and the brake anchor-nut 2. Then
turn the cam plates 3 until there 1s a total-up
the chain (in its tightest position) of about
of the chain lower-run.
-and-down free movement of
1 in., measured at the centre
E = =a = FER E . A e a a po wea wo oT
Assuming that both cam plates have the same notches engaging the
s 4 in the rear-fork ends, chai | Sul
g ends, chain and wheel alignment should auto-
matically be correct. Should slight frame-distortion exist (as the result of
a crash), it may be found that correct wheel-alignment (see page 150) can
be obtained only by adjusting the cam plates so that different notches
tye EB ——
(The Enfield Cycle Co., Ltd.)
contact the pegs in the rear-fork ends. In this instance it is desirable to
check the alignment of the chain run as well as wheel-alignment.
After adjusting the tension of the secondary chain, be sure to tighten
both rear-wheel spindle nuts 1 securely, retighten the anchor nut 2, and
check whether a rear-brake adjustment (see page 155) is needed.
Chain Stretch. lt is desirable to renew at once a primary or secondary
chain when its stretch exceeds a quarter of an inch per foot. To check
for stretch, close up a foot length of the chain, measure the exact length,
pull the links apart, and again measure the chain length. The difference
between the two lengths is, of course, the amount of chain stretch.
When Fitting a Chain. Always make quite sure that the spring link 1s
fitted so that its open end faces away from the direction of chain movement.
This is important because a chain (particularly a secondary chain) coming
adrift when travelling fast can be highly dangerous.
The Cush-drive Rear Hub (All Models). The transmission smoothness
on all Royal Enfields is largely due to the incorporation of the patent
cush-drive rear hub; this smooths out engine impulses at all speeds,
reduces any tendency for snatch in the secondary chain, and minimizes
wear of the chains and rear tyre.
As may be seen in Fig. 86, the back of the brake drum 1 (with integral
sprocket) has three metal vanes 2. Three similar vanes 3 are provided on
the inside of the cush-drive hub shell 4. Six equal-size blocks of solid
rubber 5 are placed in the hub shell, one on each side of each vane, and
the three vanes on the back of the brake drum each fit between a pair of
these rubber blocks. Thus the assembly comprises a rubber block and a
vane alternately.
No adjustment of the cush-drive is necessary, but it is advisable about
every 10,000 miles to remove the rear wheel, complete with sprocket and
brake drum (see page 154), and inspect the cush-drive. If worn, renew
the rubber blocks 5 and the lock-ring 6.
When replacing or renewing the rubber blocks, position them in the
hub shell so that they lean against each other (see Fig. 86) and provide a
lead for the metal vanes. Smear some soap (not oil) on the vanes 2 at the
back of the brake drum, and insert the vanes between the pairs of rubber
blocks. Then with a mallet deliver a sharp blow at the brake-drum centre
until the vanes go fully down between the blocks. Now replace the lock-
ring 6, insert the three bolts 7, and fit the washers and nuts 8. Tighten the
latter firmly.
Wheel Alignment. To obtain maximum tyre life and good steering, it 1s
essential that the front and rear wheels are kept truly aligned. Unless
frame distortion exists (a rare fault), moving the rear wheel backwards
in order to take up stretch in the secondary chain will not upset wheel-
alignment, except on the 1946-55 Models G, J, J2 which have a set-SCrew
adjustment, instead of twin cam-plates on the rear-wheel spindle. As
mentioned on page 147, it is essential to screw in both set-screws exactly
the same amount. If uneven wear of the tyre treads suggests misalignment
of the wheels, check the alignment.
On a solo model, place a straight-edge or a board alongside the two
wheels. It should touch the tyres at four points when the handlebars arc
placed in their normal position and the machine is jacked up on its stand
If the rear tyre IS of larger section than the front one, due allowance must
be made for this. Some riders use a taut piece of string attached to an
anchorage post for checking wheel alignment. Where a sidecar 1s fitted
the sidecar should generally toe-in to the extent of about $ in. (see Fi |
37). A suitable adjustment can readily be made. With a sidecar alienment,
also check the vertical alignment and if necessary adjust the seat-pillar
If wheel alignment is correct, dimention B should
be about + in, less than dimension A.
connexion until the motor-cycle leans outwards about Î in., measured at
handlebar clinch-bolt height. Always observe carefully the fitting i
tions issued by the sidecar manufacturers. y the liting instruc:
! The Wheel Bearings. On all models the front and rear hubs have
single-row deep-groove journal races, and the bearings require no attention
other than occasional lubrication (see page 51).
To Remove Front Wheel (All Models). On 1946-55 Models G, J, J2, and
the 1954-8 250 c.c. “Clippers” raise the front wheel well clear of the
ground by placing the machine on its stand and inserting suitable packin
(e.g., a strong box) beneath the engine. On 1949-58 350, 500 c.c. “Bullets -
and the 1956-8 350 c.c. “Clippers,” place the machine on 1ts centre stand
which is sufficiently close to the centre of gravity of the machine for the
motor-cycle to rest on both the stand and the rear wheel, when the front
wheel 1s removed. |
To remove the front wheel, slacken off the front-br ad)
and disconnect the cable (two on 1955-8 “Bullete” from the handlobar
control and from the brake-cam operating lever(s); also remove the four
nuts securing the two caps to the bases of the telescopic-fork legs. Then
lift the front of the machine (unnecessar 1 .
у where packing has been Insc
beneath the engine), and the wheel will fall away. > en inserted
Removing Quickly-detachable Rear Mudguard. On all models a quickly-
detachable rear mudguard 15 р
removal of the rear wheel, Mu
following manncr-— |
On 1946-55 Models G, J, J2 slacken the two nuts securing the mudguard
rovided to facilitate tyre repairs and the
deuard removal should be effected in the
lu TT... *.
Fra. 88. REAR View oF 1953-5 500 С.С. SWINGING-ARM
т “Ci > | if 1 the 1958 version
Che 1956-8 “Bullets” have a slightiy modified frame, anc
has a quickly-detachable rear wheel (with full-width light-ailoy hub) fitted as
| standard, instead of the non-detachable tvpe wheel shown, |
(bottom) slotted stays to the rear part of the frame, and also loosen (he
(wo nuts securing the slotted lugs at the front end of the mudguard tot
frame. Then lift the mudguard oft after first disconnecting the lead to the
ob 1949-55 350, 500 c.c. “Builets” and the 1954-8 250, 350 cc.
“Clippers,” referring to Fig. 88, to remove the mudguard slacken the
four nuts 2 and 8 (one pair on each side of the machine), and lift the mud-
guard off to the rear. This does not disturb the dualseat (where fitted).
but should it be desired to remove the latter it is only necessary to remove
the two nuts 1 (one on cach side) securing the dualseat, and lift the dualseat
-. ==; EF ор ро“. ®
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won all oe em Tw
JRA, tits. Ee
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On the 1956-8 350, 300 c.c. “Bullets,” remove the two nuts securing the
dualseat support-bracket and the front ends of the lifting handles to the
tops of the Armstrong shock-absorber attachment brackets. Then Lift of!
the dualseat, together with the rear part of the mudguard, after first scene
that the lead to the tail lamp is disconnected.
To Remove Rear Wheel (Not Quickly-detachable Type). First remove the
rear mudguard as previously described. Next remove the nut (7, Fig. 88)
from the pin securing the brake anchor-plate; also remove the adjuster
wing-nut (4, Fig. 88) from the rear-brake rod. Disconnect the secondary
chain by removing its spring link; and disconnect the speedometer driving
cable (4, Fig. 28). Then slacken the rear-wheel spindle nuts 5, and slide
the rear wheel out of the slotted fork-ends. Tilt the wheel slightly, if
necessary to enable the brake anchor-pin to disengage from its slot.
When replacing the rear wheel on “swinging-arm” models (see Fig.
88), push it forward so that the cam-plates 3 are hard np against the pegs 6
in the fork ends; on other models sce that the hub spindle abuts the set-
screws in the fork ends. This will ensure correct chain adjustment and
wheel alignment. See also Fig. 89,
Knock-out Spindle on Rear Wheel (1946-55 Models G, J, J2; 1949-53
350 с.с., 500 c.c. “Bullets”; 1956-8 350 c.c. *‘Clippers’’). On these models
having a rear wheel which is not of the quickly-detachable type it is possible
to repair a puncture very quickly without removing the rear wheel, thanks
to the provision of a knock-out spindle. To remove an inner tube with
the wheel in position, use the following procedure. First remove the rear
mudguard (sec appropriate paragraph on page 152). Next remove the
nut from the off-side of the rear-wheel spindle and tap the spindle out of
the other side. This leaves the wheel mounted on a tubular spindle attached
to the near-side fork end. Now slightly spring apart the rear fork-ends,
and slide out the knurled distance-piece between the hub and the off-side
fork end. Then slip the inner tube carefully through the gap left on the
off-side. With the distance-piece and solid rear-wheel spindle removed, it
is important not to impose any strain on the rear wheel.
To Remove Rear Wheel (Quickly-detachable Type). Available as an
optional extra on many 1956-8 models, and fitted as standard equipment
on 1957-8 “Bullets,” the quickly-detachable rear wheel (with full-widt!
light-alloy cush-drive hub permits the main portion of the rear wheel to be
removed without disturbing the secondary chain, the brake drum (and
integral sprocket), the rear brake rod, and the brake anchorage bolt. To
remove the wheel proceed as below.
Jack the motor-cycle up on its centre stand and remove the mudguard
as described on this page. Referring to Fig. 89, next unscrew the long bolt
|, applying a spanner to its hexagonal head, and withdraw this bolt
together with the adjuster cam for the secondary chain. tas advisable to
mark the cam to ensure its being replaced in its original position. Slide the
distance collar 2 out of the rear-fork end, and lift away the speedometer-
drive gearbox 3 which may be left attached to the driving cable 4. Also
remove (to prevent damage) the spacing collar and felt washer behind the
speedometer-arive cearbox. Now pull the main portiof of the wheel
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(The Enfield Cycle Co., Ltd.)
across to the olf-side of the machine to disengage the driving pins from the
~ush-drive shell and fixed portion of the hub. Then lift the wheel clear of
the motor-cycle. | Е
Reverse che foregoing procedure when replacing the wheel. When fitting
the speedometer-drive gearbox, be sure that its internal drivin g dogs engage
with the slots in the end of the hub barrel. Also before tightening the long
bolt 1. sec that the speedometer-drive gearbox is positioned so that there 1s
no sharp bend in the driving cable 4.
To Remove Rear Wheel with Brake Drum, etc. (Quickly-detachable Type).
To remove the rear wheel complete with brake drum, integral sprocket, etc,
first disconnect the secondary chain by removing its spring link; also
remove the brake cover-plate anchor nut and the wing nut from the brake
rod. Unscrew the long bolt (1, Fig. 89) two to three turns, and the near-
side spindle nut the same number of turns. Disconnect the speedometer-
searbox driving cable (4, Fig. 89) and slide the complete wheel out of the
rear-fork ends. Tilt the wheel as required to enable the end of the brake-
shoe pivot pin to disengage from the slot in the rear-fork end.
Front Brake Adjustment. To adjust the front brake for shoc wear and
cable stretch, turn the self-locking knurled adjuster-nut mounted low down
on the near-side of the front forks as required.
The 1955-8 350, 500 c.c. “Bullets” fitted with full-width light-alioy front
hubs have dual front brakes, and a knurled adjuster-nut is mounted on cach
side of the front forks. The pull on the two cables is automatically com-
pensated for by a pivoted compensating-lever attached to the handlebar
control; in consequence, precisely the same adjustment of both knurled
adjuster nuts is not essential, but it is desirable to keep the two adjusters
adjusted to approximately the same extent.
Rear Brake Adjustment. Referring to Fig. 88, to adjust the rear brake,
turn the wing nut 4 on the threaded end of the brake rod as required.
Before doing this, however, see that the rear-brake pedal 1s set 1n the best
position for convenient operation. If necessary, adjust by means of the
pedal-stop provided. To lower or raise the position of the pedal, loosen the
lock-nut 9 and turn the adjustable stop 10 anti-clockwise or clockwise
respectively as required.
To Ensure Powerful Braking. Always keep the front and rear brakes
adjusted so that the brake shoes are in close contact with the drums and
vet do not bind when the brakes are released. When adjusting the brakes,
test for free rotation of both wheels by spinning them with the wheels
raised clear of the ground.
Brake Shoes and Linings. The internai-expanding brakes have drums or
inserts (light-alloy hubs) which are free from any tendency for scoring, and
the shoes are lined with a special woven material which wears very slowly.
Note that somewhat more rapid wear occurs on the lining of the leading
shoe than on the other, because of its servo action. The brake-cam spindles
are able to float slightly in their cover-plate housings, to provide some
degree of shoe centralization and good circumferential contact with the
drums or inserts.
If Grease Gets on the Linings. Remove the brake shoes and scrape and
wash the linings in petrol. Excessive lubrication of the wheel hubs (see
page 51) is the usual cause of greasy linings which greatly impairs braking
efficiency. Normally the linings should have a polished appearance, do
not rough them up with a file. After cleaning and assembling a front or
rear brake, run the motor-cycle in second gear for half a mile or so to burn
off any grease which remains.
To Obtain Good Tyre Mileage. It is essential to keep the wheels correctly
aligned (see page 150) and the pressures in the tyres correct. Do not brake
fiercely, accelerate violently, or indulge in stunt cornering. Also go easy rider i
) ‚7 . ris of av ot à
on the clutch, remove flints or small stones embedded in the tyre treads, tyre is overage weight. A en increase in the pressure for the rear
and do not allow paraffin or oil to get on the covers. equipment is carried rider 15 above average weight or where heavy
Maintaining Correct Tyre Pressures. Over-inflation causes vibration, STEER
strains the cover, and can cause concussion bursts; under-inflation causes Steeri ING HEAD AND SUSPENSIÓN
TABLE VII ent ie Head Adjustment (All Models). Basically the steering head adjust-
. 6 1$ similar on all 1946-58 models, but there are some variations in
Tyre PRESSURES FOR 1946-58 MODELS (SOLO) regard to the arrangement of the clamping bolts. An adjustment is seld
(Shown in Ib per sq in.) called for, provided the ball bearings are ad | ! 1 PSE
Co _ a - ——— | g adequately lubricated (see page
Royal Enfield | Rear lyre E
Model Front Iyre Rear Tyre (Pillion) l
o -——— ——— 1
Model G 18 22 34
Model J 18 18 30
Model J2 18 18 30
350 c.c. “Bullet”* 18 22 32
500 c.c. “Bullet”* 18 20 32
350 c.c. “Clipper ”* 18 22 34
250 с.с. “Clipper” 18 26 38
* Where 3-00-21 in. and 4-00-19 1n. tyres arc fitted to 350, 500 c.c. “Bullets,”
the correct tyre-pressures for front and rear tyres are 21 lb per sq in. and 16 1b
per sq in. respectively. 1958 models (except 250 c.c.) have 3-25-19 1n. tyres,
and correct pressures (solo) are 20 and 24 Ib per sq in.
(Shown in Ib per sq in.)
Royal Enfield | Front Tyre | Rear lyre S/C Tyre (right) to the 1 954-8 350, 500 ec “Bullets” and 250, 3506 o e
LL _ i | I (The Enfield Cycle Co., Lids › cc. “Clippers.
Model J 20 24+ 16 .
Model J2 20 247 16 >), but If some play 1s felt, it is advisable to make an immediate ad; :
500 c.c. “Bullet” 22 25 16 unless this is done the ball bearings are liable to become damas ed. and
vibration will occur. Check for play by attempting to “shake” the handle-
+ If a pillion passenger is carried in addition to the sidecar passenger (not
recommended), increase the pressure in the rear tyre to 32-34 Ib per sq In.
Note that on the 1958 500 c.c. “Bullet” with 3-25-19 in. rear tyre the correct
inflation pressure (with sidecar) is 30 1b per sq in.
oars or, dette still, by placing one hand near the centre of the handlebars
an _Witn the other hand on the front tyre, attempting to turn the wheel
against its normal direction of rotation.
Reterring to Figs. 90 to 92, to take up play in the two ball-bearings
re place some suitable packing beneath the engine crankcase to take
ght ofl the front wheel, unless the latter is already clear of the ground.
Next slacken the head-clip clamp bolt or wedge bolt 1. If a wedge bolt is
hitted (see Fig. 91), slacken the bolt wi
| . 91), ith the special key inserted into t
internal hexagon. Also loosen the two clamp bolts 2 Securing the mai
a tendency for tyres to creep, rolling, instability of steering, and cracking of
the cover. Therefore, check the tyre pressures weekly with a suitable
pressure gauge (see page 89). The correct tyre pressures for 1946-55
Royal Enfields are given in Tables VII and VIII. It is assumed that the
tubes of the front-fork legs to the fork crown (see Figs. 90 and 91) or io
the fork head (see Fig. 92). It 1s not necessary to slacken the two clamp
bolts 5 (shown in Fig. 92) securing the main tubes of the fork legs to the
fork crown. Then take up all play in the steering-head bearings by tighten-
ing down the large plated nut 3 (behind the speedometer) on top of the
Applies to 1951-5 Models G, J, J2; 1950—3 350, 590 c.c. “Bullets,
(The Enfield Cycle Co, Ltd.)
fork head or “casquette” (1954-8 “Bullets” and “Clippers”). Tighten
down this nut very gradually and while doing so, make frequent checks for
lay. |
Soe that all perceptible play 1s eliminated from the ball bearings, but
also make quite sure there is no stifiness in the steering; with a slight push,
the front wheel should swing over to full lock. After correctly adjusting
the steering head, be careful to retighten the three clamp bolts 1 and -
The Telescopic Front Forks (All Models). Note that on all 1954 and
subsequent models the ammeter, lighting switch, and parking bulbs (see
Fig. 43) are held in place in the light-alloy “casquette” by rubber surrounds.
No adjustment to the front forks is necessary except slackening ofl’ very
occasionally some clamp bolts when a steering-head adjustment (see page
157) 1s called for.
Where the legs of the front forks are fitted with drain plugs (see Fig. 27)
It may at long intervals be advisable to top-up the fork legs with damping
oil as described on page 51. On forks with legs not fitted with drain plugs.
replenishment of the legs is not necessary unless the forks require dis-
mantling. Dismantling of the telescopic front-forks should normally not
be necessary until a very big mileage has been completed, when in some
instances oil seepage and wear of internal oil seals and bearings may
necessitate stripping-down the forks to renew the worn parts. For appro-
priate instructions, see the maker’s official Instruction Book, or Workshop
Maintenance Manual.
The Rear Suspension Units (“*Bullets”” and “Clippers””). In the event of
the springing becoming too “soft,” it is possible with 1949-53 “Bullets”
to replenish the Royal Enfield Mk. I suspension-units with damping oil
(see page 51). On late 1954-8 “Bullets and all “Clippers” the proprietary
units require no maintenance whatever. To obtain access to the inside of
the proprietary suspension-units for the removal of the springs, remove
cach unit from the frame, press down the top cover, and remove the split
collar. You can renew the springs and the rubber bushes, but any further
internal maintenance should be entrusted to the makers or an authorized
repairer. Generally speaking, dismantling of suspension-units is rarely
called for.
The “Swinging Arm” (“Bullets?” and “Clippers”). See page 54 for
lubrication instructions. Make no attempt to remove the arm for any
reason unless you have the special expander required to spread the side
members of the frame.
ACCESSORY firms, 88
Air filter, 33-4
Alignment, wheel, 150
Alternators, 61
Ammeter, 60
Automatic timing control, 101
Auxiliary oil pump, 45
charging, 62
filler, 65
first filling, 67
topping-up, 63-5
Big-end bearing, 137
adjustment, 155
lubrication, 53-4
Brushes, dynamo, 57
Bulbs, renewing, 76-9
CAMWHEEL bearings, 137
Carbon removal, 118-19
dismantling, 28-30
inspecting, 30-1
principles, 17-23
tuning, 23-8
Centre-stand, greasing, 55
stretch, 149
tension, 146
Changing gear, 10
Chromium, cleaning, 91
commutator, 58
contacts, 99
machine, 91
sparking plugs, 93-5
control adjustment, 141-4
slip, 144
Coil, 102-3
Colloidal graphite, 15
Commutator, cleaning, 58
Compensated voltage control, 59-60
т лин. "Ш. = ——— ен —т ÍA | вы nn
gap, 96-9
lubrication, 46
Contacts, cleaning, 99
Controls, use of, 3-7
Crankcase and gearbox removal, 138-
41, 146
Crankcase breather, 41, 43
| Cush-drive rear hub, 150
| Cylinder—
barrel removal, 114, 123-4
head removal, 109-14, 124-7
Decompressor, 105-7
Dipper switch, oiling, 55
Drain plugs, front forks, 52
brushes, 57
removal, 6
ENAMELLED parts, cleaning, 91
| Engine—
bearings, 136-8
nuts, tightness of, 128
oils, 36
flame, 24
valve lifter, 4, 105
| FELT filter, cleaning, 43
Filter, air, 33-4
Focusing headlamp, 74
| Foot gear-change, greasing, 54
Front forks, 51-2, 159
| Front-wheel removal, 151
| Fuei consumption, high, 28
| GAP—
contact-breaker, 96-9
sparking plug, 93
| Gear changing, 10-12
| Gearbox—
lubrication, 47
~ removal, 138-41, 146
* “
_ w am
Gear control adjustment, 145
(Generators, types of, 56
Greases, suitable, 50
Grnding-in valves, 121
HANDLEBAR controls, oiling, 53
Headlamps, 68-74
Hul chmbing, 11
Horn, electric, 79
7.1. pick-up, 102
=u» lubrication, 51 —
Hvdrometer, use of, 65
ming, 129-34
‘rouble, diagnosing, 86
= 7 needle, 20, 27
Lisht-umit assembly, 72
Linings, brake, 155
centre stand, 55
cnart, 48
Zipper switch, 55
001 gear-change, 54
-ront forks, 51—2
zearbox, 47
nandlebar controls, 53
‘Magdyno,” 45
magneto, 46
>rimary chain, 47
secondary chain, 48
sidecar chassis, 55
speedometer drive, 53
steering head, 51
swinging arm,” 54
~heel hubs, 51
"MAGDYNO” lubrication, 45
Magneto lubrication, 46
Main jet, 20, 25, 28, 30
Maintenance, items for, 89
“Monobloc” carburettor prin
Moving off, 9
NEUTRAL finder, 5, 12, 145
OESTRUCTION, pilot jet, 27
ciples, |
Oil-bath chain case, 47
circulation, 37—9
consumption, increased, 44
filter, cleaning, 43
leakage, gearbox, 47
pump, 39—41, 44
tank, 35, 41, 43
| PARKING machine, 13
tank removal, 108, 129
taps, 7
P1lot-air screw, 20, 26
| Pilot jet, 20, 26, 27
— Piston—
removing, 115, 123
rings, 116-18
seizure, 15
"Preliminaries, 1
| Primary chain—
adjustment, 146-7
lubricating, 47
REAR-suspension units, 54, 159.
Rear wheel removal, 152-5
Rectifiers; 61
Red reflector, 2
Riding position, 3
— Rocker-box lubrication, 41
| Running-in, 14, 35
adjustment, 147-9
lubrication, 48
Short circuits, avoiding, 56
| Sidecar chassis, greasing, 55
Slip-ring, “Magdyno,” 102
Slow-running, bad, 27
Small-end bearings, 136
| Spares and repairs, 88
Sparking plugs, 92-6
Specific gravity, battery, 65-6
Speedometer drive, lubricating, 53
Spring arm, removing, 100
Starting engine, 8-9
— Steering—
damper, 13
head adjustment, 157
head lubrication, 51
engine, 13
machine, 13
Storage battery, 67
Sump, draining, 41
“Swinging-arm” pivot, 54
Switch positions, 4, 73
TAIL lamps, 74-5
lappet adjustment, 103-5
Terminals, dynamo and C.
cut-away, 22, 26
stop, 20, 26
Timing case, draining, 42
Timing cover, replacing, 45
Tools, 89-90
V.C. unit, |
| WARMING up engine, 36
| Wheel—
| Fopping-up battery. 63-3
Tyre pressures, 155-7
| UPPER cylinder lubricant, 15
' VALvE timing, 134 6
| Valves—
removing, 120
replacing, 122
alignment, 150
bearings, 151
— Wiring—
details, 86
diagrams, 80-5
Roval Enitie
1961 700 c.c. Constellation
309-325 High Road, Chiswick
London, VW. 4
Telephone: CHiswick 6368-Sales, 2246-Spares
THis book will give the careful reader a sound
grounding in driving methods. Concentrating
first on the actual handling of the car, 1t will
shorten the time required for road instruction
and it will make that time less trying and less
anxious for both pupil and instructor. The
objective in this volume 1s to concentrate first
upon basic principles; to inculcate a systematic
approach to all driving problems so that the
driver will be capable and confident in tackling
the different road conditions of different coun-
tries as well as the changes that occur as a
conseguence of the introduction of new regu-
lations or of new devices In the car itself.
6s. net.
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