IN STEVAN RADAKOVIC'S HANDS, ROY SHEARWOOD;S GOLD STAR IS A CHAMPIONSHIP-WINNING MACHINE.
After many years as "bridsmade" bedfordshire based Stevan Radakovic finally took the 1997 Jim Lidgate Memorial Junior Historic Racing Championship, aboard a BSA Gold Star. The pace of this and other push rod, roadster~based machines has, over the past few seasons, begun to match that of the pukka Manx Norton and AJS 7R race~ware, so what better time to check out just what makes Radakovic's bike tick ? The machine actually belongs to Roy Shearwood, a name familiar to long~standing Historic race aficionados, from titanic Triumph~mounted battles with John Armstrong on Andy Savage's 500 Manx Also Bedfordshire born and bred, 43'year~old Roy came from a bike~orientated family and grew up with Enfield ace, Steve Lindsdell Roy made his VMCC debut aboard a rigid 350 Gold Star in 1976 with several machines following over the years, including 500cc Gold Stars and the trick Thunderbird which was fitted with a Norton crank to give 704cc This machine, incidentally later powered John armstrong to , to many to mention top places ,also Dave Longstreeth to Unlimited Championship honours Roy then moved into the sidecar class, with wife Ruth in the chair of a BSA Al0 which they campaigned for four years and finished fourth in the championship During this time, Roy had joined forces with Roy Coyle to form Tudor Motorcycles, Local lad, Stefan Radakovic, was a regular customer and enquired about going racing When he lined up a Norton single for his debut at Pembrey Stef's tuner / spannerman at that time was another former historic racer, Vic Farnhill , and in the early 1990's they were joint owners of a Manx M30. Tudor Motorcycles backed the inaugural Champion of Champions handicap - itself the brainwave of Roy Coyle - and Radakovic won it, along with the Senior Championship and duly earned the No.1 plate. However, the following season was spent with the Classic Club but the Manx was not as quick as the Seeleys etc and success was limited Times becoming tight resulted in the sale of the Manx and it looked like an enforced retirement for Radakovic until a chance conversation with - Roy Shearwood By now out of racing through back injury missed the excitement of Historic racing.with a basement full of goldstar parts suggested to Stef that they should have a go together . roy originally built the bike with the intention of a neighbour racing it when time permitted , it needed to be run in and Stef offered his services The rest, as the cliche goes is history .devolopment continued and stef's championship results increased steadliy ,third in 1994 ,a brace of runner up spots in1995 and 1996 and finally the title in 1997.

Based loosely on a 1956 DB32 - with B31 crankcases the first motor pushed out a lowly 22bhp( rear wheel ) Nothing special compared to stock Clubman figure (quoted !! ) of 30.bhp Stef's initial lap times at Mallory Park were in the region of Im 13s Today after much development,the motor makes(39bhp@ wheel ) (42bhp @ crank ) at 7, 500rpm with perfect power and torque curves.stef's best 57s
So how has it been a achieved? "With a lot of a hard work and heartache," grins Roy ,Starting from the bottom, the crank is a work of art - a perfectly crafted, pressed up, needle roller job with slim steel flywheels. together This throws an Arias forged, big bore, squish piston via the obligItatory Carillo rod and The crank rod ratio is down from 2.6:1 to 2:1 by means of a shorter stroke. Dimensions are practically square at 76.5 x 76, 349cc - a long way from the stock Goldie's 71 x 88 first rebore takes the motor over the capacity limit. "It's a bit of a pain" says Roy "because it means I have to replace the sleeve but it's worth it because there's no pride in winning - through cheating, which we would be doing if to a we simply bored it." The method of reducing the barrel height is also rather novel. Most would remove metal the from either the top. bottom or both but Roy takes it from the middle! The barrel is bored out to take the new oversize liner and then is cut in half The appropriate amount of metal is removed from the bottom of the top half and the top of the bottom half before being heated up The liner is pressed into the bottom half, the top then dropped over the liner, with the pushrod tunnel lined up and then allowed to cool The seam is then welded up and is as good as invisible The cylinder fins genuinely act as just a cooling muff for the liner Cams are stock Gold Star Roy states "BSA's original profile is difftcult to improve upon but I have an ex-works development cam.from Roland Pike, which I'd like to try some-Time Although the inlet valve is central, the tract on a Gold Star is to one stde of the head, and to mount an enormous carburettor in that position results in the instrument fouling the rider's leg To overcome this, Roy cut away the manifold stub, welded up the hole and rewelded a down-draught stub central over the valve The finished work looks standard however the mod controversy was soon quashed when Roy produced pre-1957 factory documentation to prove that this development was pursued Valves are 42mm inlet, 36mm exhaust but surprisingly are of steel Roy is planning on using titanium valves with a fused hardened cap but Roy chose not to experiment with them last season, opting for reliability due to the close championship battIes between Stef and rival Stuart Tonge on his highly-developed, twin-carb G3 Matchless Much dyno work has been undertaken over the past few years but things really began to take off when Roy .utilised a rolling road dyno . With the original open mega- phone, the motor was tuned to give maximum - bhp at 8,5oorpm and Roy was pleasantly surprised to find that the use of a silencer (end can) had negligible effect on performance. Since then, however, the primary pipe length has been altered for improved mid-range and Roy has fitted 'ramps' into the primary pipe to prevent low pressure gases from creeping back into the combustion chamber and pushing them into the high pressure flow (NOTE these had to be placed excatly in the right place or losses were incured )Roy says "We might have lost an odd horse or so from the very top end but we gained an incredible IO to 12 in the middle which made the bike so much better out of corners." The use of a twin plug head, powered by encapsulated twin outlet coils via a crankshaft-triggered ignition renders the magneto and intermediate pinions redundant, thus saving weight Early wetght-saving exercises included the use of Dural pinions but their wear introduced an unacceptable amount of swarf into the oil and have since been junked in favour of lightened steel items Compression ratio is 13:1, running mainly but not entirely on methanol Restraining such a big squeeze is taken care of by a series of throughbolts from the head, through the barrels and into the cases A 36mm Amal GP carb with remote float chambers feeds the fuel. Rocker gear is mildly lightened and balanced Castrol R40 is the regular lubricant "Many of the lads now swear by Morris's but I've always been more than happy with Castrol; that said, I'll change with pleasure if I'm offered a good deal," says Roy with a grin. Gearbox internals started as standard fivespeed Triumph but are now a mixture of Triumph and other pinions which gives a wellbalanced close-ratto Roy modestly says "The original stock four-speed BSA box needs a bit of work - but nothing much" This explanation actually means the almost total gutting of the case, machining of bearng housings, opening up intermediate case to accept a home-made selector mechanism and the making. machining and fitting of an intermediate case section to allow for the extra pinions The transmission feeds through the well respected Newby clutch Presently this item sports a 30mm belt but Roy is looking at high efficiency (and lighter) 25mm belts which are constructed in such a manner that they trap no air when mating with the pulley Although practically identical to the stock BSA frame and maintaining the original head stock angle Roy's frame is self-manufactured from lightweight T45 tube Erratic handling was initially accredited to the forks but when slow motion video footage was examined, it was found to be caused by swing-arm flex This has since been gusseted and original rubber bushes replaced by ball races with a spacer amidships Further improvements were found in the use of needle roller bearings The swingarm spindle, along with many other fittings and all nuts and bolts, are titanium. Koni 'dial-a-ride' rear shocks are used, while many varieties of japanese front forks were examined for their damping arrangements Roy eventually found their internals to be too big a diameter for the BSA fork so his alternative solution was to machine down the bushes into an ' H shape to reduce .stiction' and shims with varying diameter holes were incorporated into the system to adjust the rate of damping (a la Duckhams Norton White Power twin shocks) .'i thought about using a transfer port arrangement to prevent the oil from entraining air but with insufficient room inside the fork slider it would have meant a small bore externally mounted pipe to allow the oil to travel from bottom to top under compression and I think the (historic Racing) Committee would have found that more than enough reason to ban us, because it detracts from the original external period appearance," says Roy however, there was adequate space within the front brake drum to make up the necessary linkages to convert to a twin-leading shoe The rear brake is stock With alloy tanks and wheel rims shod with the Avon rubber the Shearwood Gold Star tips the scales at a very competitive 260lbs ~ quite a considerable saving over the standard Goldie's 365lbs - - Next season will see an equipe of identical Shearwood Gold Stars - in the hands of Radakovic, Martin Page and Duncan - Walmsley With the junior models more than matching the cammy jobs, maybe soon we'll - - see a Shearwood 5OO take on Seniors ?

Stevan went on to retain his titel in 1999 ,had a more relaxed year 2000 in has much that fewer meating were enterd ,but still claimed 4th place in the 350cc championship class with the Classic Racing Club , He his in the prosses of building a new lighter (faster) better model for 2001 season c r m c club ..... who know' watch this space .
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