RS Framed Evolution

Dates of detail changes to Velocette models can be confusing as changes were announced for the  model year in September / October of the previous year. More than likely these changes would have already been put into production even before they were announced. Occasionally some changes were phased in by model to use existing stock. Therefore this information can only be used as a guide.

Date

Model / Engine Number

Event

1952
Dec
Spring framed MAC introduced
1953 Mar New top gasket for the oil filter housing introduced
MAC chain case modified
MAC number of clutch springs increased to 16
July "O" ring fitted to exhaust valve lifter cam
July M17/4 cam superseded by M17/5 on MAC
Sept Oil pump feed gears reduced to 3/16" on MAC
Sept Minor change to rear suspension units. Nuts originally used to secure steel covers, replaced by collets to secure aluminum cover 
Sept New oil tank transfer A 134/4 replaces simple line transfer A 134/2
Sidecar lugs added to MAC frames
Dec MSS introduced, originally fitted with prefix 12 gearbox
1954
Feb
Carb setting changes on MAC
Mar 16 T gearbox sprocket and stiffer front fork springs available for MSS when pulling sidecars
May Primary chain covers modified to accept felt ring - note MAC and MSS primary covers have different part numbers
June Spacer added between inner and outer primary chain covers
June Miller headlight 79CV now standard on MAC / MSS, this requires different bulbs
June MAC now uses MSS silencer MAS30/2
MSS Scrambler introduced with no sidecar lugs on the frame
MSS Endurance introduced US market
June MAC22659
RS3709
Prefix 11 gearbox replaced by heavyweight prefix 14 gearbox. MAC now uses 12 clutch springs compared to the MSS 16
Sept MAC 23142 K87 ball main bearing superseded by roller bearing K87/2
Sept 12 - 2195
14 - 1604
First gear wheel, now fitted with two bushes rather than the one full length bush
Nov MAC 23193 M17/7 cam and followers M9/5 fitted to MAC
MAC and MSS handlebars finish changed from enameled black to chrome
Spokes changed from black enamel to plated
Amal air lever changed from a long lever to short lever and separate horn and 'Lighthouse' dip switch replaced by a combined Miller switch 157H.V.3

Rear number plate now changed to enclosed two piece and "Round Diamond" Miller rear light changed to either 37ET tail lamp or 38ET stop and tail lamp

1955 MAC Now available in green as well as black

Loch Ness monster seat replaced by seat with pointed front

April Veloce ordered first Monobloc carbs from Amal to replace 276 range
May Gaiters added to front forks and two way damping added to Scrambler
July Scrambler rear fork torque tubes now doweled
Aug All fibre washers replaced by soft alloy washers

MSS

Solid skirt piston replaced by split skirt piston

MSS11786

Engine studs increased from 5/16 to 3/8 Crankcase MAS 29/3

MSS 11889
(RS6890)

Prefix 14 gearbox made standard, rather than previous prefix 12

Gaiters replaced shrouds on Scrambler *

Petrol Cap moved from left hand side to right hand side of tank

Petrol tank lining changed on MSS and MAC
MSS, pillion footrests, steering damper, stoplight and air cleaner no longer standard but available as optional extras
MAC also available in green

Dec

Venom and Viper introduced

1956 Endurance available in the UK
Apr MAC 24630 Stem diameter of exhaust valve increased

Squarer type rear light introduced to MSS

Mar VR Scrambler introduced
May MSS 11970
(RS6818)
MAC 24284
(RS7535)
V belt replaces flat belt and new dynamo belt covers fitted
MSS 12078 Band primary chain case changed to screw type

May

MAC
MSS 12239

Headlamp nacelle carrying switch ammeter and speedo. Speedo changed from 80 to 120MPH. Diacon tank badges replaces transfers on petrol tank.

MSS 12303, VR 1144, VM1114

Flywheels reduced in size, 0.0625" narrower, 0.75" less in diameter

May Lower selector fork rod superseded by one 1/16" longer
May Engine crash bars available
June MAC24677
(RS8480)
Cast iron cylinder replaces Alfin type

June

VM1227
(RS8488)
 VR1222
(RS8323)
VM inlet tract diameter increased from 1.125 to 1.1875, consequently carburettor changed from Monobloc 389/14 to 389/15. VR inlet tract increased from 1.0 to 1.0625 consequently carburettor changed from Monobloc 376/56 to 376/61
June

VR1262
(RS1615)

M17/7 cam replaced by M17/8 on Viper

MSS

Drive side bearing boss diameter increased, crankcase MAS 29/4

Petrol tank knee grips moved further back
Oct Reinforced rocker box gasket specified
Oct Stronger ATD springs fitted (possibly to Viper only), however these were replaced with the original types in August 58
Nov VM1503
(RS9136)
VR1375
(RS9225)
Modified oil tank and breather arrangement for Venom, MSS and Viper
1957 Light alloy rims, close ratio gears, racing seat, clubman pipe and silencer, two way damped forks and other items were first catalogued to comply with certain racing regulations 

Miller stop light switched changed from 44E to 44EV, which is similar to the previous switch, but with a special 'drain hole' for Velocette MAC MSS Venom and Viper.

Sept

Modified oil tank and breather arrangement for MAC

1958

Flatter seat used

Regulator moved to rear mudguard under the seat

May MSS 12542
(RS10906)
VM 2206
VR 1720
(RS10917)
Valve retaining collar and associated components strengthened 

Oil tank lugs strengthened

Silencer now made with heavier gauge material

June

MSS 12561
(RS11006)
 VM 2216
(RS10927)
VR1837
(RS11314) 

Extra drive side plate added

Nimonic 80 exhaust valve used on Venom and Viper

Aug VR 1837
(RS11314)
Extra drive side plate on Viper standardised. Previously an extra
Sept MSS12585S
(1001/35)
MSS Scramblers fitted with triangulated frame
Sept Glassfibre engine covers available
Dec VR1922
(1003/35)
Viper Scrambler introduced

1959

Froth tower added to oil tank, breather vented to rear chain and shorter neck fitted

Timing cover with casting for rev counter drive now fitted as standard

Sept MkI Venom and Viper Clubman listed for 1960 season
Ball ended levers introduced on Clubman models together with reinforced exhaust and silencer, rear sets, close ratio gearbox, BTH TT Magneto, TT carburettor, taper petrol taps, two way hydraulic dampers and revised rubber mounting of the petrol tank. Rev counter, megaphone and alloy rims extra.

1960

Cylinder head changed from sand cast to die cast

Change to frame lower tubes now welded - engine / mudguard mounting changed from original casting

14/4916 12/7081

Gear change linkage changed from a well-engineered component to a piece of bent scrap iron!

Lubrication of the big end revised with the oil feed to the center of the crank pin.

Cast iron cylinders replaced Alfin barrels

Oil scavenging tube lowered in crankcase

Aug MAC discontinued

Sept

Miller dynamo uprated from 36 watts to 60 watt D6

Sept Venom and Viper Clubman fitted with 41/4 gallon tank with badges and aluminum trim. The tank is mounted by two straps front and back and two pins which locate in a front frame lug which are supported by rubber buffers. Seat changed as a result of the larger tank.
Sept Venom and Viper Veeline and Veeline Clubman's introduced with Dolphin fairings
Ribbed front tyre used on MSS
Deepening ratchet on kick-starter to prevent slippage
Some machines fitted with Girling rear dampers
Dec Veeline fairing available to order for retrofitting
Dec TT ratios now not fitted as standard to Clubman machines

MSS 12915, VM 5049, VR 3605

Dynamo pulley increased in size

1961

Veeline fairings introduced

1962

VM  5551 Rear of petrol 4.25 gall tank mounted on rubber block
Early 62 "O" Rings fitted to cylinder studs on VM, VR and MSS
Nov

VR4121
(RS17010)
VM5690
(RS17042)

4.25 gallon tank introduced on standard models

Nov Venom and Viper Specials introduced with non chrome three gallon tank, pressed steel full width hub, MSS/MAC rear hub (later changes again) 60mm, 100 MPH speedo in modified nacelle

TT carb optional on Viper

1963

Woodhead Munroe suspension units replaced by Girlings on MSS, Venom, Viper - Specials still Woodhead Munroes

Crankcase includes timing chest drain rib MAS 29/4

Sept VR, VM Clubman Clubman's fitted with Monobloc as standard rather than the previous TT carb

Sept

VR4372
(RS18170)
, VM5690, MSS13120
(RS18180)

Crankcase suction filter replaced by blanking plugs, Oilways increased in section, crankcase halves now located by dowels MAS 29/5, crankcases heat treated on Thruxton

1964

Chronometric Speedos and rev counters replaced by magnetic

Jan

"Thruxton" head now optional on Venom as part of a production racing kit including petrol and oil tanks

1965
June

Thruxton introduced

1966
June

Miller electric's phased out, Lucas gradually introduced

Sept VMT421
(RS18889)
Rear tyre reduced in width to 19 X 3.25 and cast lloy brake and gear change levers replaced the earlier items

Oct

VR4542
(RS19077)
VM6265
(RS19018)

Engine breather changed requiring modification to oil tank, crankcase MAS 29/6

Deeper skirted dual seat fitted

Oct VR4541
(RS19079)
VM6289
(RS19020)
MKII Clubman introduced
Red line marked at 6250RPM on Thruxton rev counter
Polished alloy rear brake and gearchange lever replaced the pressed steel brake lever on Thruxton and Clubman rear sets

1967

VM 6362 / VMT 506

Fork stanchion diameter and bushes increased in diameters

New Smiths Speedometer drive fitted to rear wheel requiring new bearing retaining ring, clamping sleeve and distance piece. Venoms and Vipers shown with 36 spoke hubs in spare parts list

Exhaust pipes reduced from 1.75" to 1.5" on Venom Clubman and Thruxton

One piece push rod tube introduced

New seat with skirt that follows frame introduced

Amal Concentrics fitted as standard

Battery box fitted as standard on all models with a new horn tucked away behind it

Venom, Viper fitted with Thruxton mudguard stays

Thruxton rear tyre changed from 3.50 to 3.25 section

1968
July/Aug

VM 6488C

Coil ignition replaces Magnetos with ignition switch in the battery box lid - only one VR 4584C apparently fitted with coil ignition

Viper and MSS discontinued

Thruxton barrels now fitted to Venom with extra compression plates

All bands and badges replaced on petrol tanks by transfers and gold lining

1969
Jan
VM6459
(RS19636)
VR4579
(RS19498)
Venom and Viper Specials discontinued
Viper Clubman, Veeline and Scrambler discontinued
MSS scrambler discontinued in the UK - for export only
Some clutches fitted with a two part plain clutch bearing to replace the large diameter ball race
On some bikes the humped backed seat was replaced with the flat seat
Some bikes fitted with plain bearing in the chain wheel to replace the ball race

1970

Last Thruxtons fitted with 36mm Amal Concentrics

1971 Feb All production ceased

 

Date

Optional Extras

1953
Dec
Panniers for MAC / MSS
1954 Panniers for MAC and MSS
1955 Chrome plated fuel tank available as an optional extra for the MSS. Panniers, air cleaners, steering damper, pillion footrests and stop light and switch available as extras for MAC and MSS
1956 Chrome plated fuel tank available as an optional extra for the MSS. Panniers, air cleaners, steering damper, pillion footrests and stop light and switch available as extras for MAC and MSS
1958
Sept
Chrome plated fuel tank available as an optional extra for the MSS. Panniers, luggage grid, pillion footrests, full width front and rear hubs and stop light and switch available as extras for MAC and MSS. Reinforced engine plate for MAC, MSS and Viper. Amal TT Carburettor, and light alloy wheel rims (Viper and Venom). BTH racing magneto and manual control, ball ended levers, taper petrol taps, Miller 60W dynamo, air cleaners, steering damper, rear sets, Clubman exhaust system, TT gear ratios, Rev counter with TT magneto only, two way damped forks, exhaust magaphone, safety bar.  Two level dual seat at no extra cost.
1959
Nov
Chrome plated fuel tank available as an optional extra for the MSS, all enameled for the Venom and Viper. Panniers, luggage grid, pillion footrests, safety bar, full width front and rear hubs and stop light and switch. Reinforced engine plate for MAC, MSS and Viper. Amal TT Carburettor, and light alloy wheel rims (Viper and Venom). BTH racing magneto and manual control, racing seat, ball ended levers, taper petrol taps, Miller 60W dynamo, air cleaners, steering damper, rear sets, Clubman exhaust system, Rev counter with TT magneto only, two way damped forks, exhaust pipe extension or magaphone. Sidecar gear ratios and front fork springs. Polished engine and gearbox instead of covers on Viper and Venom at no extra cost. Two leveled dual seat at no extra cost.
1960
April
Chrome plated fuel tank available as an optional extra for the MSS and Endurance and all enameled for the Venom and Viper. Panniers, luggage grid, pillion footrests, safety bar, full width front and rear hubs and stop light and switch. Reinforced engine plate for MSS and Viper. Amal TT Carburettor, and light alloy wheel rims (Viper and Venom). BTH racing magneto and manual control, ball ended levers, air cleaners, steering damper, Rev counter with TT magneto only, exhaust pipe extension or magaphone. Sidecar gear ratios and front fork springs. Rear view mirror. Two leveled dual seat at no extra cost. Polished engine and gearbox instead of covers on Viper and Venom at no extra cost.
1961
Sept
Chrome plated fuel tank available as an optional extra for the MSS and Endurance. Panniers, luggage grid, pillion footrests, safety bar, full width front and rear hubs and stop light and switch. Reinforced engine plate for MSS and Viper. Amal TT Carburettor, and light alloy wheel rims (Viper and Venom). BTH racing magneto and manual control, ball ended levers, air cleaners, steering damper, rev counter with TT magneto only, exhaust pipe extension or magaphone. Sidecar gear ratios and front fork springs. Rear view mirror. Two leveled dual seat at no extra cost. Polished engine and gearbox instead of covers on Viper and Venom at no extra cost.
1964
Jan
Panniers, luggage grid, pillion footrests, safety bar, full width front and rear hubs and stop light and switch. Plated rim for Specials. Reinforced engine plate for MAC, MSS and Viper. Amal TT and 1 3/8" GP carburettor, Large valve cylinder head, oil and petrol tanks for large valve head and light alloy wheel rims (Viper and Venom). BTH racing magneto and manual control, ball ended levers, air cleaners, steering damper, rear sets, Rev counter with TT magneto only, magaphone, "blown" racing type screen, chrome guards, polished aluminum guards. Sidecar gear ratios and front fork springs. Rear view mirror. Two leveled dual seat at no extra cost. Polished engine and gearbox instead of covers on Viper and Venom at no extra cost.
1965
May
Panniers, luggage grid, pillion footrests, safety bar, full width front and rear hubs and stop light and switch. Plated rim for Specials. Reinforced engine plate for MAC, MSS and Viper. Amal TT and 1 3/8" GP Carburettor, Large valve cylinder head, oil and petrol tanks for large valve head, double leading shoe front brake and light alloy wheel rims. BTH racing magneto and manual control, ball ended levers, air cleaners, steering damper, rear sets, Rev counter with TT magneto only, exhaust pipe extension or magaphone, "blown" racing type screen, chrome guards. Avon Dolphin type front fairing. Sidecar gear ratios and front fork springs. Rear view mirror. Two leveled dual seat at no extra cost. Polished engine and gearbox instead of covers on Viper and Venom at no extra cost.
1966
Oct
Panniers, luggage grid, pillion footrests, safety bar, full width front and rear hubs and stop light and switch. Plated rims for Specials. Reinforced engine plate for MSS and Viper. Amal 1 3/8" GP Carburettor, Large valve cylinder head, oil and petrol tanks for large valve head, double leading shoe front brake and light alloy wheel rims. BTH racing magneto and manual control, ball ended levers, air cleaners, steering damper, rear sets, Rev counter with TT magneto only, exhaust magaphone, chrome guards. Avon Dolphin type front fairing. Sidecar gear ratios and front fork springs. Rear view mirror.