BSA Competition Dept History
Notes on a Conversation with Graham Horne (ex Comps Dept on the left above)
Works 500s had works engines not B50 engines.
Vic Vaughan reckons the stud spacings were something like 74mm for the 441, 76 or 78 for the works 494 and 80 for the B50.
Not all the works engines had magnesium cases. At times the comps shop people went on to the production line, grabbed aluminium cases, finished but prior to stud hole boring , bored the different centres and mounted the magnesium top end.
Early mag cases broke and so an extra lug appeared under the engine. Graham remembers making up special engine plates to pick up the extra lug.
As a stopgap they even resorted to bolting a steel strengthening plate inside the gearbox that went through and picked up the rear frame lugs.
Sand cast aluminium heads and barrels were heavier than production square barrels and heads.
The titanium bikes weighed 202lbs.
Wheel spindles, engine nuts, cam wheels, gearbox shafts, nipples, valve caps and cups were all made from titanium.
Rear discs on the titanium bikes did not work.
Titanium bikes had iron rims - I remember my early Victor having high tensile rims and I still have ‘em.
Alloy hubbed wheels were heavier than old steel hubbed wheels (- is that why so many pictures show the mag fork sliders with the old hubs?)
There were first and second string riders.
JVS, Vic Eastwood (who was always in trouble for modifying his bike - see p.137 of Roy Bacon‘s book, ceriani forks, 494 motor, fibreglass panels), John Banks, Keith Hickman and Dave Nichol were first string.
For some reason Arthur Lampkin was second string.( See p139 of RB’s book - Arthur with early mag forks, 494 motor, GP frame, glass panels, JB with later forks, ally panels, late frame.
Vic Eastwood got the factory to build him a frame that was an inch lower than the others.
Firsts got the magnesium bits, seconds the aluminium.
When they needed them, the likes of Arthur and Dave Rowlands could go down the production line, grab a GP frame and carry on. The later trials bikes even with C15 engines appear to have GP frames. I don’t know what mods if any were done to them. There are photos of Scott Ellis on pp309 and 310 on oif bikes, that on p. 309 appears to have a nickel plated frame, mag yokes, pre-mag works fork legs and Bantam hubs.
Details from the Motor Cycle 5 Jan 1967
JVS’ bike (after the titanium debacle}
Return to Reynolds 531
Larger diameter front down tube
All engine oil carried in the frame tubes
Small header tank gone (signalling the end of the definitive GP era)
Lighter gauge tubing - frame only 6lbs heavier than titanium version
Titanium front fork yokes, footrests and valve gear retained
494 cc engine retained with modified cylinder head and porting
Lower and more luxurious seat
High level front mudguard
Rear mudguard stay (on JVS bike)
Fibreglass side panels (still)
In the same issue is a picture of Vic Eastwood on a 494,fibreglass side panels, what must be a magnesium front hub, cobbled front mudguard stay, also Arthur Lampkin on a 441 with old front hub, mag sliders, also Vic Vaughan on a bike made from bits of JVS 420, built by Bernie Singleton (JVS mechanic post-65) with pre-mag forks.
Classic Bike Report July 1982
Comparison of Tim Law’s various old moto-crossers, G85CS, alleged B50, Metisse etc.
This is not a B50 - it looks like a 1969, possibly 1968 works bike with the 494 magnesium motor with bolt in bearings, non-folding footrests, titanium gear lever, chrome or nickel plated frame, non-B50 conical rear wheel, aluminium side plates, tubular, high front mudguard stay.
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