The myth surrounding this machine was not bestowed on the bike by owner Ken Bayliss, or rider 2007 and 2008 British Classic Scrambles Champion Andy Roberton but by its outstanding results on the track.
Having competed with Andy Roberton most of my life as a professional motocross rider it would be difficult to find a more stylish or fair rider to compete against. Bike owner Ken Bayliss I’ve only met since watching Andy compete at a few meetings but he comes across as the perfect sponsor. Rather quiet with a genuine warm welcome when encountered at meetings, the Bayliss approach is of a man enjoying being involved but in a pleasingly introverted way. The Bayliss/Roberton partnership could never be accused of over-the-top presentation at race meetings, with a low key approach to their presence in the paddock.
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Ken and Andy are both engineers and share bike preparation, a daunting task for the two seasons and 160 races the pair have been together. It therefore saddened me that a myth emerged that Andy was riding a bike so exotic it cost between £15,000 and £20,000 depending on who was telling the tale. The old tale, of the older I get the quicker I was, must have applied itself to the modern classic bike scene. In Andy’s case the more races won, the more the bike must have cost. This is sheer nonsense as the list of parts used in creating the bike indicates a lot of readily available stuff has been used. Maybe now the whispering brigade will realise the success of the bike is down to the dedication of the rider to achieve a speed and consistency and meticulous preparation. What is a fact, the cost of building a competitive classic scrambles bike is much more than a modern motocross bike.
Andy brought both his 500 and 350 along on the day of the test, for comparison, though the main purpose of the day was to ride his 500 in the condition it finished the last championship round. Apart from cleaning and a general once over where a torque arm broke – nearly costing the title and could have caused a serious accident – this was the case. It is still a mystery why the torque arm broke as the material spec was correct. Fatalism is a belief held by most motorcycle racers and fate certainly played its part in the last meeting of the Championship run by the Mortimer MCC. Everything hinged on the last race after the unlucky Adrian Cox had mechanical problems in the first race and Andy needed to finish in the top six were turned on their heads when the brake arm broke and he had to ride with the forks stuck at the bottom of their stroke. History says Andy finished fifth in the race and winning the title on the most wins system.
There is always a dilemma of what is required in a championship winning machine and ‘lightest bike, most power and the fastest rider’ is the unbeatable combination. If we were looking for pure horse power Arthur Browning’s Jawa engine as used for the Red Marley Hill Climb would win hands down, but reality and some good machine regulations make for a compromise in building a competitive bike.
To this end the most consistently competitive bike in the Pre-68 class is the B44 BSA Victor based engine models. Crankcases and cylinder head must be of original design but just about everything else is open to modification. The Bayliss bike used the regulatory crankcases and head from the B44 along with genuine B44 flywheels, Omega piston and a Carrillo con-rod.
The well developed components produced by Nigel Bowers at NEB Engineering are used in the rest of the engine. A three-speed gearbox, clutch and cylinder barrel give virtually bulletproof components to an engine running on methanol and producing brake horse power figures so far in front of the old works BSA figure of around 30bhp. Back in the day not once did these bikes spin the clutches on the tapered gearbox mainshaft. Move forward to 1976 on the CCM with still the basic BSA motor – but now producing a lot more horsepower – the clutch was spinning off at every early season race.
Quaife three-speed clusters with a splined shaft for clutch holding cured the problem then and now. Like the CCM of 1976 Andy uses Interspan ignition developed by Fred Stoneham with ongoing development to this day, although some people do not like idea of having to charge up their system.
An Amal concentric carburettor of 32mm bore delivers pure methanol to the motor and once set up properly requires no re jetting to keep running and pulling like only a four-stroke can. With the rules restricting the crankcases and cylinder head, it leaves valve size and cams as the major player in power delivery. There is minimal opportunity to enlarge the valves in a B44 so the bike uses standard dimensions. The cam configuration is the B50 MX one, without doubt the best all-round cam for the traditional strong bottom and midrange power associated with these type of motors.
My first adventure into classic road racing was using a B50 road bike converted to road race trim and using the MX cam. The distance gained coming out of the tight corners just about made up for the distance lost along the straight. The same rings true with fitting other cams to the B44 motor, you might gain at the top but the trade off is loss of pull at bottom end, the scrambler's best friend. We now have a picture of a very original engine set up with no exotic materials, run on methanol giving the two fold advantages of a lot more bhp and a cooler running motor keeping that power for a longer period of time.
Testing
Our test venue was provided by Phil and Colin Edwards on their farm near Bromyard. Two farming brothers with a great passion for classic scrambles with Phil notable for battling a methanol burning 650cc Triumph Cheney with considerable success and brother Colin going for a single cylinder BSA Victor.
What a piece of land, a large piece of rolling countryside providing a valley with high hillsides. After frost, rain and snow on the build up to the test on the day conditions were perfect to ride a scrambles bike, almost heaven in fact. Nick Haskell was commissioned to the task of photographing this enjoyable escapade and this seemed appropriate as I remember him well, bursting on to the scene as a young whippersnapper.
Scrambling bikes for over 45 years has given the poor old body a bit of a hard time and starting bikes is not one of my favourite pastimes – firing up a BSA scrambles engine was never an easy task. Factory BSAs of ’71 never had a kick-start fitted so a push start was mandatory. A bike on methanol in the cold is an even worse scenario so Andy was nominated to do this, after all it is his bike and he is only 60. Before the test I thought I’d better get a new fog-free lens for my Oakley goggles, at great expense I may add, and when I tried to give Andy a push they were hanging off my wrist. Struggling to keep up and at the vital bump period of the procedure the goggles got trapped between the tyre and the shock. Before I had even started riding my new lens was severely scratched. A typical mad keen motorcyclist doing daft things and proving we were not in heaven yet.
The grassy track was in prime condition, grip was in abundance and it did not take long to start enjoying the 500. Before the test though I asked Andy what he would buy given the choice of bike? Without any hesitation he said it would be a 500cc single cylinder unit BSA. After Andy’s advice my mate Bob Pearson acquired a 500 Cheney BSA to play on in 2009. Back to the Bayliss machine, after a few laps on what at one time would have been described as a mountain grass track, the characteristics of the old works BSA to the more enhanced bhp of the CCM showed why Andy loves these bikes.
Instant power when the throttle was snapped open, coming out of the sweeping corners, allowed a controlled drift or with a more gentle feeding in of power, going round an adverse camber corner, perfected the execution of the most difficult of manoeuvres to perform that which only a classic scrambles single cylinder engine can produce.
Once really hot this motorcycle, even with a main jet that a bumble bee could probably crawl through, would tick over like a trials bike. In this probably lies the secret of Ken’s championship winning bike with Andy working to produce the sweetest of carburetted bikes, even allowing for difficulties associated when using methanol. With the lack of recent riding my level of fitness was to prove the deciding factor, therefore when the mind wanted to go fast it would have to be done in short periods of three or four lap stints. This motorcycle suits small riders, I’m 5ft 6in, touching the ground with both feet was no problem, although I doubt Andy Roberton is able to, but with his riding style there is no need. The benefit of a low centre of gravity created from having 6½in travel at the front and 4in at the back makes for a machine to go round tight corners at a greater speed than a modern bike.
With the tester relishing the bottom and midrange power we were able to gauge the top end grunt as well with a full out climb in top gear from the bottom of the valley to the top of the track of over 400 yards. This resulted in cresting a two tier rise culminating in long, fast, controlled wheelies.
Does the three-speed box compromise the top end? The answer would be yes, but only if the straight was of an exceptional length. The 500 Cheney BSA is fast at top end but with horses for courses. I am sure Phil Edwards on his methanol twin cylinder 650cc Triumph engine Cheney would have little difficulty passing the British Championship winning bike on a long straight.
Listening to Andy and Phil talking about racing into the first corner at a 2008 meeting, is this not the whole point of us competing to realise our moment of joy, be it last week or 40 years ago, it soon became apparent the sheer power of the Triumph would gain the individual advantage. With starts never too long to the first corner Andy would be close enough for the lighter bike agility and greater engine braking effect to sneak past Phil to gain that crucial advantage round the first corner.
Conditions were ideal for the test but if we were to encounter conditions witnessed during the last Championship at Reading then this BSA would be the better bike to ride.
The TV races of the 60s, dominated by the great Jeff Smith, were made for a lightweight 500cc BSA with a dry weight of 207lb and even using a road camshaft for more tractability. So bhp is not the be all and end all of scrambles, but if you want to win today’s scrambles championship, using methanol is inevitable.
No jumps on the circuit to test but plenty of suspension-bottoming dips at the bottom of the valley to encounter at high and low speeds. As one of an army of supposedly paddock experts watching Andy ride last year, and a little bit of suspension static bouncing up and down in the pits my thoughts were it must feel like riding a modern bike as Andy makes it look like that way. The truth is the suspension is good and lets you lay the power to the ground in perfect conditions, but when it gets bumpy and hard suspension dips are encountered there is no way in this world a bike with 6½in movement at the front and 4in at the rear is going to handle like a modern bike, and does my back know it.
The first part of the front fork stroke on this bike is good but when confronted with a really hard dip there is a hard reaction through the handlebars. The rear units respond in the same sort of way resulting in a harsh encounter at the bottom of suspension travel, although in no danger of losing control it is not what you expect when watching Andy riding the same machine.
It is not a cheap motorcycle to build and Andy and Ken have been very helpful in disclosing the full facts of the bike. All parts are readily available for anyone to buy, which is good news, the bad news is attention to detail and riding ability is not available for money. The 350cc would not be something I would have thought about when deciding what to ride in 2009. Though the test has made me think again it is too late for me. Virtually the same as the 500, with a different bore and stroke latched to a four-speed box the bikes are as different as chalk to cheese.
When Andy and I rode Bultacos in the ’70s the production bikes weighed 203lb for the 250cc and 206lb for the 360cc but both bikes were so different to ride and we agreed we liked the 250 more than the 360. Three pounds in weight meant nothing, so the big bike feel came from the characteristics of the engine. I had this feeling with these two bikes and I would have to say that for someone like myself who has not been riding classic bikes I found the 350 a real joy.
The bore and stroke allows for a freer revving engine that feels smoother right through the rev range. Without the out and out torque of the 500 motor the free revving 350 felt least exhausting to ride, giving more time to keeping the throttle full open coming out of corners or later going in.
The four-speed BSA box was geared closer together helping to keep the motor revving at its higher peak and therefore a very good speed, surprisingly close to its 500cc brother. Not as tractable as the 500 coming out of the slower corners the bike had to be worked harder but once again the slightly lighter bike and appropriately easier feel of a 350 made it a joy to hustle round and still plenty of grip compared to a two-stroke. It felt better at the bottom of the dips but with the same rear units and better forks it was an easier ride, giving me more confidence to go fast. I am sure there is a lesson here for riders who are getting older or have less ability than Andy Roberton and want a fast, single cylinder four-stroke that is enjoyable to ride.
Summing up my day was easy, it was great. The championship bike is the ultimate 500 single for scrambles, fast, light and engineered out of ready available parts with no exotic materials added. It proves no matter how its power feels the biggest contributor to its successes are its owner, Ken Bayliss and rider Andy Roberton. You would have to be an exceptional person to win the main championship riding a 350 only but not impossible, more importantly, to 98 per cent of the classic racing scene, it’s just fun to be out there racing so maybe a 350 would be more fun. 
