RS Framed Velocette Evolution

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July		M17/4 cam superseded by M17/5 on MAC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Sept	MAC 23142	K87 ball main bearing superseded by roller bearing K87/2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.