34 Creating a legend
Catalogue correct doesn’t often cut it on the track, where performance is all.
Putting a Triumph engine in a BSA frame makes a… Beezumph… hmm that name is taken… how about TRIBSA…?
In the motorcycle world there are any number of reasons to create a special with components from various sources. These reasons range from ‘couldn’t afford a catalogued machine’ to ‘the standard offerings weren’t right’ and often include ‘had a load of bits’ and ‘sheer bloody-mindedness’, to give just four examples. Some such specials or ‘bitzas’ are more common in one sphere of the sporting world than others, for instance the combination of Triumph engine in a Norton frame is evocative of the café racer scene, while slipping a Triumph engine into a BSA frame is much more common in the scrambles world. The resulting TRIBSA was and is arguably a better clubman machine than the BSA Gold Star that often donated the rolling chassis. Now before the Gold Star Owners’ Club gangs up on me, I have to say the Goldie is a superb machine – but in order for it to produce the best it can do, a comprehensive maintenance schedule has to be followed, as it is pretty much a race engine. The problem was, not all club-level riders could afford the maintenance and parts that had to be replaced or rebuilt after a certain number of hours. There was a tendency to think ‘we’ll get another meeting out of it...’ and all of a sudden there’s an engine-shaped hole where the engine used to be.
Luckily Triumph’s versatile twin engine was relatively cheap and much more easily maintained by the enthusiast watching the pennies, and it wasn’t difficult to fit into the BSA frame. Those who had the Gold Star chassis got quite a high spec, but there was no real need to go that far as even the B31/B33 and the later swinging arm A7/A10 chassis was an all-welded one to the same dimensions as the Goldie. Okay, so it had a few more brackets and whatnot, but hacksaws and files sorted that out and the twin frame didn’t have the oil pump kink in the lower frame rail – but with a Triumph engine, it didn’t need it.
After that it was up to the rider/builder and the success or otherwise of the project would depend on the ability of those involved in it. There was no reason why marrying a Triumph engine into a BSA chassis couldn’t produce a winning combination, as that was what the Rickman brothers did with their Metisse before they began to build their own frames. There was an archetypal ‘look’ for the TRIBSA and in order to be considered serious, certain components had to be used in the build. Though things are slightly different now, in the glory days no self-respecting TRIBSA would be seen without Norton forks keeping the front end up, or either the BSA or AMC competition gearbox tucked in behind the engine. As for the engine, Triumph handily produced an all-alloy 500 which was nice and light and had a full package of cams, pistons and carburettors either off the shelf at the dealer or in the breaker’s yard. Some alloy sheet, a bit of hacksawing and filing, then drilling to make the engine plates, and it was starting to look like a bike now. Royal Enfield made an almost streamlined primary case and a Manx Norton clutch fitted inside it quite nicely, thank you. If the budget ran to it, either a Manx or 7R rear wheel could be used, though these were not common and the benchmark BSA crinkle hub tended to be the choice of most people. Up at the front there were lots of choices available, but most tended to settle for a single-sided hub either from the Goldie or some other model in the BSA range. The scalloped 500T Norton hub too was seen, or maybe they were the standard hubs with a few scallops taken out carefully.
Some alloy mudguards, alloy fuel and oil tanks which could be bought or made if the skills were there, a cut-down saddle, scrambles bars and controls, a pair of knobbly tyres, and the TRIBSA was ready for action. Triumph’s engine produced nice, flexible power and could be improved as the rider progressed; there were bigger engines if the class allowed and so on.
The TRIBSA certainly filled the gap between the demise of the factory four-strokes and the rise of the reliable two-strokes and even when the two-strokes did arrive, the era of the special was not over. This is where the sheer bloody-mindedness often displayed in our sport kicked in, and mutterings were along the lines of ‘I know the BSA Victor is lighter and just as fast but damn it, I like riding the TRIBSA…’ No one ever said our sport was ruled by common sense.
Enter the classic scene, because there are those who prefer to race older motorcycles because the table-tops, double jumps, loop the loops and so on which you simply have to do – ahem, yes, a bit tongue in cheek there – in modern MX aren’t for the likes of us and the sound of the older bikes is good too. In the early days of classic sport the bikes were ridden by lads who’d had them back in the day and tucked them in the shed as the reality of racing say a Goldie against an RM500 in the modern scene kicked in. Now with an excuse to get out there, these machines were hauled out and the same problems arose in the classic scene as they had in the earlier period. These problems included supply and demand; not enough Goldies, or G80CSS, or whatever your chosen classic for the racer was, but still lots of BSA frames and Triumph engines available. These days there are some seriously stunning bikes as it seems we – as a collective rather than just you and I – have a shilling or two more to spend on our hobbies and building a special with a BSA frame and a Triumph engine isn’t as daunting as it used to be.
A field in Northampton early in 2018
Taking a trip to Northampton for the Northampton Classic Club Ltd’s Classic Scramble proved productive for the CDB team, at least as far as bikes to write about were concerned and we, photographer Gary Chapman and I, came away with full memory cards in his case and a full notepad in my case.
Turning up early on day one we caught people before they were fully aware of what was going on and they agreed to be posed here, there and everywhere, which is how we trapped Dave Godley. Just lining up his bikes for the weekend, we asked if his pre60 TRIBSA could be pulled forward so that we could take some pics. Then, before he could escape, I asked him about the bike in great detail.
Clearly the bike was built for going rather than showing – all Dave’s machines follow this ethos, which is a good thing as there’s little point in looking at a shiny bike while all the fun is on the track. While it does look typically period, there are a few notable things which help it in the modern world. As Gary caught the light here, the reflection there and that sort of thing, Dave told me the frame was a replica rather than a genuine Bsa-made one and as such was a little lighter than standard. “It’s to all the same dimensions as a BSA frame and unless I tell you it’s a replica it isn’t obvious though there is a clue...” Looked fine to us; looking over the bike so I could ask pertinent questions or show my ignorance depending on your view, the ‘clue’ became obvious… it’s an oil-in-frame chassis.
I saw the popular Ariel swinging arm in place. Now BSA did a nice tubular one which was stiff enough until the action got dirty and it could twist or flex. Ariel – at the time owned by BSA – had this oblong section swinging arm with dimensions more akin to the old Forth Road Bridge. This swinging arm went on to the HT and HS Ariels and maybe other models too, but once fitted it was strong and kept the rear wheel in line. In the rear end of the swinging arm is BSA’S crinkle hub, which joined the range in the Forties, was still used on various models 20 years later and even when the group decided to tackle the ISDT one last time in the legendary 1973 American event, the rear hub of choice was a ‘crinkle.’ Up at the front though it’s a different story… “What the heck is that behemoth in the forks?” I gasped. “It’s from a Norton Dominator twin,” grinned our man. “It works but perhaps isn’t as stylish as some other front hubs.” Hmmm, I would allow that with the output from a 750cc TR7 top end on the 650 bottom end on tap then perhaps ‘works’ over ‘stylish’ wins out. Anyway, keeping that hub in place is a pair of Norton Roadholder forks but with Marzochi internals. “This conversion was done by Bowder Engineering about 10 years ago,” said Dave. “The billet yokes are theirs too but would have originally had Bultaco forks in them.” The actual Bulto forks aren’t legal for pre60, nor are Marzochis for that matter, but their internals are and few people will use the standard forks these days.
We’ve touched on the engine as having a later 750 top end on it. This has a four plug head fired by a PVL electronic ignition and the idea behind the four plugs – two per cylinder – is to give a more controlled burn rate and a touch more power from a higher compression ratio allowed by super unleaded petrol. The electronic ignition, whichever make is chosen, has to be the best invention ever in the history of everdom for users of old motorcycles; reliable sparks come rain come shine. A special has little need to adhere to any particular components unless there are specific reasons for them to be used. Our builder chose to fit better parts and AMC’S gear box as used by lots of bikes in the range, right up to the Norton Commando eventually, is a strong and tough unit. “There’s just the standard cluster in there,” said Dave. “I’ve mounted the footrest on the end cover as you can see but you can’t see the Suzuki clutch inside the primary case, I’m planning on changing it to a Norton one though.” With the engine and gearbox often from different machines, there could be some issues with lining everything up as mounting point width may well be different. In reality this isn’t a problem as accurate measuring with all components in place will show if distance pieces are needed or perhaps a little bit of machining to ease off a lug here or there. As long as the engine plates bolt up and hold the engine and gearbox in place, all will be well. Way back in the early days of the classic magazines there was a series aimed at the road racing scene in which a known name of bike building revealed a few secrets to success, one being he always bolted things together from the rear of the chassis with the final pieces being the front engine plates. Along the way, any distance pieces were made and fitted. This gave a stress-free build – stress of the components we mean as no build is stress free for the builder.
On the rear end of this TRIBSA are NJB shocks. A development of the Girling units which were for so long an industry standard, these units work well and are rebuildable, as well as looking period too. “I’ve an Amal Concentric carb on, I use Morris Heavy Duty V-twin 20/50 in the oil reservoir, not sure what else I can tell you,” Dave said. “Primary cases?” I asked. “Early A10, handlebar controls are a side-pull throttle, Amal levers and Renthal bars, though I made the foot brake lever.” In the end, though the TRIBSA may well have a few modern touches, it’s still a classic machine and all credit to Dave Godley for wrestling it around what turned out to be a fairly muddy track with people slithering all over the place.
Classic looks and style from the mix ofTriumph and BSA.
Pretty much the classic ‘look’ for a TRIBSA, an AMC gearbox is fitted here. BSA’S ‘box works just as well if one is available.
Few people these days don’t use a sidepull throttle. They were available in the era – BMW used them – but it took a long time for the competition scene to adopt them.
Front suspension didn’t come any better than Norton Roadholders in the Fifties; however, 60 years on, most people hide modern internals in the old legs… wonder if that can work for riders?
As rear hubs go, the ‘crinkle’ from Small Heath is a desirable fitment, get one if you’re building a special.
Described by the owner as ‘an ugly lump but it works’ the sls drum was originally from a Norton Dominator.
It helps, when fitting different engines into BSA frames, that physical dimensions of various twin motors are similar.