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ROYAL ENFIELD 350cc and 500cc O.H.V. WORKSHOP MANUAL
Page 4
DATA
ROYAL ENFIELD 500 c.c. O.H.V. MOTOR CYCLE
ENGINE.
Cubic Capacity
...
...
...
...
...
... 499 c.c.
Stroke
...
...
...
...
...
...
... 90 m.m.
Bore
...
...
...
...
...
...
... 84 m.m.
(3.30725in. - 3.30675 in.)
(Rebore to •015 in. when wear exceeds .008 in. and again to
.030 in. after further .008 in. wear.)
Compression Ratio ................... ... ....... ... ........ ... ....... ...6.75 to 1
Piston Diameter:
Bottom of Skirt
Fore and Aft
... 3.3047 in./3.3042 in.
Top Lands . ... ....... 3.284 in./3.281 in.
Piston Ring Dimensions-
Width-Plain Rings
... ........... ........ ... ....1/16 in.
Scraper Ring
... ........... ........ ... ....5/32 in.
Radial Thickness .......... ... .115 in./.108 in.
Gap when in unworn cyl.
.012 in. to .016 in.
Clearance in grooves .................................... .0035 in./.0015 in.
(Renew Piston Rings when gap exceeds 1/16 in.)
Oversize Pistons and Rings available.
Piston Boss Internal Diameter ............. .. .7500 in. - .7495 in.
Gudgeon Pin Diameter ............. ... ....... .. .7500 in. - .7495 in.
Small End Bush Internal Diameter
(fine bored or reamered after fitting) .7507 in. - .7505 in.
Big End Bush Internal diameter
(ground after fitting) ........................ ... .... 1.625 in. ± .00025 in.
Crank Pin Diameter .................. ... ....... ... 1.249 in. – 1.24875 in.
Main Bearing Outer Race inside diameter
(before fitting) ............ ... ....... ... ...... .. 1.3752 in. – 1.3750 in.
Timing Side Bush inside diameter
(reamered after fitting)
... ...... ... .877 in. - .875 in.
Driving Side Shaft Diameter
... ...... ... .8750 in. - .8745 in.
Timing Side Shaft Diameter
... ...... ... .8750 in. - .8745 in.
Roller Diameter .............. ... ....... ... ...... . .2500 in. - .2490 in.
(Graded to nearest .0001 in. and selective assembly used.)
Rocker Bearing inside diameter .6255 in. - .6250 in
Rocker Diameter ............ ... ....... ... ...... ... .6240 in. - .6235 in.
Valve Guide inside diameter (before fitting)
.3447 in. - .3437 in.
Valve Stem Diameter-Inlet .................. ... .3435 in. - .3425 in.
Exhaust ................................................. ... .3415 in. - .3405 in.
Valve Tappet Clearance (with cold engine)
Inlet
.002 in.
Exhaust
.004 in.
Valve Timing at .005 in. tappet clearance
Exhaust opens
75° before b.d.c.
Exhaust closes
35°
after t.d.c.
Inlet opens
40° before t.d.c.
Inlet closes
70°
after b.d.c.
Valve Spring Free Length (outer and inner)
1.3/4 in.
(Renew valve spring when free length is reduced by 1/8 in.)
Cam Bush inside diameter (reamered
after fitting) ................ ... ....... ... ....... ... .6255 in. - .6250 in.
Idler Pinion Bush inside diameter (reamered
after fitting) .................... ... ....... ... ....... ... .502 in. - .501 in.
Cam Spindle .................. ... ....... ... ....... ... .6245 in. - .6235 in.
Idler Pinion Spindle
.. ....... ... ....... ... .49925 in. - .49825 in.
TRANSMISSION.
Sprockets-Engine ...................... ... ... 21 T.
1
/
2
in. P. X .305 in. W,
Clutch ..................... ... ... 42 T.
1
/
2
in. P. X .305 in. W.
Countershaft
... ... 18 T.
5
/
8
in. P. X .380 in. W.
Rear Wheel ............. ... ... 46 T.
5
/
8
in. P. X .380 in. W.
Chains-Front
...
... 75 pitches
1
/
2
in. P. X .305 in. W.
Rear
...
... 89 pitches
5
/
8
in. P. X .380 in. W.
Chain Adjustment-Front
... ....... ... ....... ... .........
1
/
4
in. slack.
Rear
... ....... ... ....... ... .........
1
/
2
in. slack.
Clutch Thrust Rod Length
... ....... ... ....... . long part 9
7
/
16
in.
short part 1
7
/
8
in.
Clearance in Clutch Control
... ....... ... ....... ... ....... ... ......
1
/
16
in.
Gear Box Ball Bearings-
Large Internal Dia. 30 m.m.
External Dia. 62 m.m.
Width 16 m.m.
Small Internal Dia.
5
/
8
in.
External Dia. 1
13
/
16
in.
Width
5
/
8
in.
Gear Box Layshaft Bearings (reamered after fitting)
Left side Internal Dia. 1.001 in. – 1.000 in.
Right side Internal Dia. .7195 in. – .7185 in.
Kickstarter Shaft Bearing Internal Dia. 1.1255 in. – 1.1250 in.
FRAME AND WHEELS.
Wheel Hub Ball Races
Front-Internal Diameter
5
/
8
in.
External Diameter
1
9
/
16
in.
Width...
...
...
7
/
16
in.
Rear-Internal Diameter
5
/
8
in.
External Diameter
1
13
/
16
in.
Width...
...
...
5
/
8
in.
Wheel Rim Size ...
W.M.2-19in. for 3.25-19 in. Tyre.
Front and rear rims interchangeable.
Wheel Spokes
Front, near side
... ... 6
5
/
8
in. long 8-10g butted.
Front, off side ............. ... ... 8
3
/
4
in. long 8-10g butted.
Rear, near side ........... ... ... 7
3
/
4
in. long 8-10g butted.
Rear, off side .............. ... ... 8
1
/
2
in. long 8-10g butted.
Spoke lengths measured under head.
Nipples are .140 in. dia. x 40 T.P.I.
Cush Drive, allowable free movement at wheel rim when rear
brake is on ... ... ...
1
/
2
in. to 1 in.
Steering Head Balls
... ...
1
/
4
in. dia. 38 to set (19 each race).
IGNITION.
Contact breaker gap
............................
0.012 – 0.015 in.
Ignition Timing (Advanced) ..........................
3.
/
8
in. before t.d.c.
............................ (34° Advanced)
Spark plug type
...... 14 m.m.
1
/
2
in. reach Lodge C.14 or
...... Champion L.10S.
CARBURETTER
Carburetter type
......
Amal. 276
Main jet Size
......
Between 140 and 170
Throttle Valve
......
4
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