Section A3 - Royal Enfield SPRING FRAME O.H.V. 250cc CLIPPER 1954 Workshop Maintenance Manual

ROYAL ENFIELD WORKSHOP MANUAL
Cubic Capacity
Stroke
Bore Nominal
Actual
(Rebore to .020 in. when wear exceeds 005 in. and
again to .040 in. after a further .005 in. wear.)
Compression Ratio
Piston Diameter-
Bottom of Skirt Fore and Aft.
Top Lands
Piston Rings-
Width-Plain Rings (Two)
Scraper Ring (One)
Radial Thickness
Clearance in Grooves
Renew Piston Rings when gap exceeds
Oversize Pistons and Rings available .020 and .040 in.
Piston Boss Internal Diameter
Gudgeon Pin Diameter
Con. Rod Small End Diameter
Con. Rod Big End Diameter
Floating Bush Ext. Diameter
Floating Bush Int. Diameter
Floating Bush Width
Crank Pin Diameter
Engine Shaft Diameter
Driving Side Main Roller Bearing
Outside Diameter
Inside Diameter
Width
No. of Rollers
Timing Side Main Roller Bearings-
Outside Diameter
Inside Diameter
Width
No. of Rollers
Size of Rollers
Diameter
Length
Graded Rollers are available in steps of .0001 in. from
Rocker Bearing Inside Diameter
Rocker Spindle Diameter
Inlet Valve Stem Diameter
Exhaust Valve Stem Diameter
Valve Guide Internal Diameter
Valve Guide External Diameter
Guide Hole in Cylinder Head
Tappet Stem Diameter
Tappet Guide Internal Diameter

SECTION A3

Technical Data
"250 Clipper" Engine
248 c.c.
77 mm
64 mm
63.970 mm/2.5185 in.
6.5 to 1
63.926/63.901mm
63.50/63.45 mm
.0625/.0615 in.
.15625/.15525 in.
2.612/2.460 mm
.0035/.0015 in.
1
/ in.
16
.7500/.7498 in.
.7498/.7495 in.
.7510/.75025 in.
1.6257/1.6252in.
1.6235/1.6230 in.
1.2502/1.2498 in.
.739/.736 in.
1.24900/1.24875in.
1.0000/.9997 in.
1.876/1.875 in.
1.5002/1.4998 in.
1.437/1.432 in.
24 (2 rows)
1.8772/1.8770 in.
1.5004/1.5002 in.
.4425/4405 in.
12 (1 row)
.2500/.2490 in.
.328/.327in.
.2490 in.-.2500 in.
.626/.625 in.
.624/.6235 in.
.34275/.34175 in.
.34175/.34075 in.
.3452/.3437 in.
.624/623 in.
.623/622 in.
.375/.374 in.
.3765/.3750 in.
Tappet Guide External Diameter
Guide Hole in Crankcase
Tappet Clearance with cold engine-
Valve Spring Free Length
(Renew when reduced by
Valve Timing with .012 in. clearance-
Exhaust Opens
Exhaust Closes
Inlet Opens
Inlet Closes
Cam Spindle External Diameter
Cam Bush Internal Diameter
Cam Lift .
Valve Lift (approximately)
Contact Breaker-
Speed
Points
Timing
Engine Sprocket
Clutch Sprocket
Final Drive Sprocket
Primary Chain
Type
Length
Width
Pitch
Feed Oil Pump
Speed
Piston Diameter
Stroke
Return Oil Pump-
Speed
Piston Diameter
Stroke
Sparking Plug
Type
Diameter
.875/.874 in.
.875/.874 in.
Inlet .002 in.
Exhaust. .004 in.
13
Inner 1
27
Outer 1
3
/ in.).
16
75° before B.D.C.
35° after T.D.C.
30° before T.D.C.
60° after B.D.C.
.6245/.6235 in.
.6255/.6250 in.
.3125 in.
.3125 in.
Half Engine Speed
.015/.018 in.
3
/ in. before T.D.C.
8
advanced
1
/ in. before T.D.C.
64
retarded
17 Teeth.
42 Teeth.
15 Teeth.
110046 Renold
66 Pitches.
.305 in.
.500 in.
1
/ Engine Speed.
12
.25 in. (nominal)
.375 in.
1
/ Engine Speed.
12
.375 in. (nominal)
.375 in.
Lodge H 14.
K.L.G.F70.
Champion L10S.
14 mm
/ in.
16
/ in.
32