ROYAL ENFIELD WORKSHOP MANUAL
SECTION A2b
Technical Data
" 500 Bullet Engine " 1953-1955
Cubic Capacity ... ... ... ... 499 c.c.
Stroke ... .. ... ... 90 mm.
Bore ... ... Nominal .. 84 mm.
Actual .. 3.30725/3.30675 in.
(Rebore to .020 in. when wear exceeds .008 in. and again to
.040 in. after a further .008 in. wear.)
Compression Ratio ................................ .. . .. 6.75 to 1
Piston Diameter.
Bottom of Skirt.Fore and Aft ... 3.3047/3.3042 in.
Top Lands ... ..... 3.284/3.281 in.
Piston Rings
Width.Plain Rings (Two) ... .063/ .062in.
Scraper Ring (One) ... .156/.155 in.
Radial Thickness ........................... .. .115/.108 in.
Clearance in Grooves.Plain Rings .0035/.0015 in.
Scraper Ring .0035/.0015 in.
(Renew Piston Rings when gap exceeds 1/16 in.)
Oversize Pistons and Rings available.. .up to 0.60 in.
Piston Boss Internal Diameter ... .7500/.7497 in.
Gudgeon Pin Diarreter ............ ... ......... ... .7500/.7497 in.
Con. Rod Small End Diameter .. ... .7507/.7505 in.
Con. Rod Big End Diameter ... ......... 1.62625/ 1.62575 in.
Crank Pin Diameter ... ... 1.24900/1.24875 in.
Con. Rod Floating Bush.
Outside Diameter ............. ... ......... ... ..1.6235/1.6230 in.
Inside Diameter ................ ... ......... ... .. 1.2502/12498 in.
Width , Late 1953 onwards .......... ... .983/.980 in.
Width, Early 1953 models.. .......... ... .736/.739 in.
Driving Side Main Ball and Roller Bearings
SKF.CRL.8 and SKF.RLS.8.
Outside Diameter .......................... ... .... 2.25 in.
Inside Diameter ................ ... ......... ... .... 1 in.
Width ...................... ... ........ ... ......... ... .625 in.
Timing Side Main Roller Bearing..
Outside Diameter ............ ... ......... ... 1 .876/ 1 .875 in.
Inside Diameter ... ........ ... ......... ...1.5002/1 4998 in.
Width ...................... ... ........ ... ......... ... .750 in.
Size of Rollers.
Nominal Size ........... ...1/4 in. dia. x 21/64 in. long
Diameter ................ ... ........ ... ......... .. .2500/.2490 in.
Length ................................ .. .328/.327 in.
Rocker Bearing Inside Diameter .626/.625 in.
Rocker Spindle Diameter .................... ... .6240/.6235 in.
Inlet Valve Stem Diameter .3430/.3425 in.
Exhaust Valve Stem Diameter .3410/.3405 in.
Valve Guide Internal Diameter .3447/.3437 in.
Valve Guide External Diameter .6275/.6270 in.
Guide Hole in Cylinder Head .626/.625 in.
Tappet Stem Diameter ............... ... ........ ... .375/.374 in.
Tappet Guide Internal Diameter ... .3760/.3752 in.
Tappet Guide External Diameter . 7510/.7505 in.
Guide Hole in Crankcase ..................... .... .750/.749 in.
Tappet Clearance with cold engine
Inlet ... Nil
Exhaust ................. ............ ... ........................... Nil
Valve Spring Free Length
Inner ... ......... ... .......... 2.032 in.
Outer ... ......... ............ 2.095 in.
(Renew when reduced by 3/16 in.)
Valve Timing with 012 in. 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.
Cam Spindle External Diameter ... .6240/.6230 in.
Cam Bush Internal Diameter ............... .. .6255/.6250 in.
Cam Lift .................................................... ... .... .3125 in.
Valve Lift (approximately) .................... ... .... .3125 in.
Magdyno
Speed ... ........ ............ ... ......... ... .. 1/2 Engine Speed
Points ... ........ ............ ... ......... .. .012/.015 in.
Timing (Advanced)... ..... ............ ... ......... 5/16 in. before T.D.C.
Engine Sprocket ............ ............ ... ......... ... ........... 25 Teeth
Clutch Sprocket ............ ... ........................ 56 Teeth
Final Drive Sprocket.
Solo ........... ... ........ ............ ... ......... ... ........... 21 Teeth
Sidecar .................. ............ ... ......... ... ........... 18 Teeth
Primary Chain..
Type .......... ... ........ ............ ... ......... ... Duplex No. 114038
.................... ........... ............ ............ .............. Endless
Length ... ........ ............ ... ......... ... .......... 90 Pitches
Width ... ........ ............ ... ......... ... .628 in.
Pitch ... ........ ............ ... ......... ... .375 in.
Feed Oil Pump
Speed ............................... ............ ... ......... ... 1 /12 Engine Speed
Piston Diameter ............ ... ......... ... .24975/.24950 in.
Stroke .............................. ............ ... ......... ... .5 in.
Return Oil Pump
Speed ............................... ............ ... ......... ... . 1/12 Engine Speed
Piston Diameter ............ ... .37475/.37450 in.
Stroke ................... ............ ... ......... ... .5 in.
Sparking Plug
Type ........... ... ........ ............ .. ..... Lodge HLN, KLG FE80
Champion NA8 Long Reach
Diameter ... ........ ............ ... .......................... 14 mm.
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