It has been a ‘Good news Bad news’ sort of month for the Rex-Acme, PUB, and AJS ‘Medieval’ Mary.
The all too infrequently used sidevalve HRD was exercised again for the Brackley Motorcycle Festival in Northamptonshire. Brackley has grown to be quite a major event, with thousands of visitors on a good day, although this year’s weather forecast was poor and kept some away. The main USP (unique selling point) is the way that Brackley permits the High Street to be closed, and barriers erected to produce a paddock and circuit where RealRacers can be demonstrated at speed. It is not the only attraction, as there are stalls, a fairground, and separate off-road display rings, club and manufacturer stands, etc. PUB even took advantage of the latter to try a couple of the modern 400cc middleweights for size – the need for an electric leg is making itself felt.
This year a new (to the event, PUB thinks!) guy by name of Sammy Miller attended, intent on demonstrating his Gilera four and ohc BMW, which he proceeded to do to good effect. PUB watched as ever-competitive Sammy followed a hot Vincent 1000 on his 500cc racing BMW. But following is not Sammy’s style, and within a couple of laps he closed in and then got by at the slow corner, no doubt to go after the next bike. It was worth going just for that, as spectators get quite close to the action.
More recreation was provided by the annual Kop Hillclimb at Princes Risborough in Buckinghamshire. PUB could only attend on the Saturday, which attracts slightly fewer vehicles than Sunday, but still found plenty to look at. Motorcycles varied from the Hummerstones’ veteran 1914 Sun-Villiers, to a modern supercharged Kawasaki H2R. This is one of the places where it can almost be guaranteed to see a Brough Superior being used – and the rider will probably give it a
bit of stick off the line too. Rick Parkington bravely left his Rex-Acme Blackburne unattended, severely tempting PUB to have it away as a replacement for AJS Mary’s troublesome Villiers model. Cars somewhat outnumber bikes, but they do include interesting stuff such as the Edwardian Berliet with Curtiss aero-engine, and sports cars from C & D type Jaguars to humble Austin 7-based Ulster and Gordon England ‘Brooklands’ models. PUB drooled over the little Berkeley with its 700cc Royal Enfield engine and light weight leading to a similar top speed to the bike’s, hence its B95 model designation (the firm also offered a hotter B105).
The Kop soapbox race has become a popular established event within an event and showcases a lot of ingenuity – there was a Risborough Community Bus, a Fire Engine, whilst Mr Bumble appeared to be an Ant accompanied by Bee helpers. Keeva Hart and Sophie Goodall sculpted the front of their entry ‘Naphill Railton’ to echo the famous Brooklands lap record holder – hopefully they put up a good time themselves. Fergal Moore and Oscar Byrne showed their ingenuity differently with their soapbox name – Byrne Moore Rubber!
However the season for (most) motorcycle events and shows is nearing its end, having provided PUB with plenty of interesting bikes and pictures to share. The season of AGMs is upon us (PUB has three vying for her attention in the next few weeks) but they will not provide good copy for the RC readership. Auctions are lining up too, with Alexandra Palace having just passed, but the Barber Museum (USA, featuring Steve McQueen memorabilia and bikes, an Ascot-winning Gold Star, and a green frame Ducati 750SS) and the Autumn Stafford Show (Rem Fowler
memorabilia and exotic old V-twins galore) are just ahead, although they will be behind when this column is read.
At Alexandra Palace the highlight bike was a 1974 3-cylinder MV Grand Prix machine. PUB expected it to exceed its estimate (£120160,000) but the cognoscenti must have detected something a little lacking or amiss in its history, for it hammered down for only £110,000 (£126,500 inclusive of commission). For comparison a more ordinary 1978 MV 750S America, admittedly with only 41 miles on the clock, still made £74,750 (inclusive of commission). As ever, it seems that proven history is really important, and people will pay for it, so that the ex-Harry Lamacraft MkVIII KTT Velocette which raced in the 1939 TT netted £50,600, whilst the serious race / TT history in the hands of well-known riders lifted the 1961 350cc Beart-Norton to £51,750. Other bikes were (slightly) more affordable, but who would have thought that Lambrettas would ever change hands for over £8000?
Turning to events at home, it has also been a busy time in PUB’s shed, mostly on the RexAcme but also tinkering with other things that may get a mention later when other news is in short supply. Is the Rex-Acme now running, then? Well, yes and no, but it has been another voyage of discovery investigating the actual workings of the Villiers automatic lubrication system – mostly to conclude that petroil is a much simpler solution!
Firstly, however, the bike needed to start and run right, which did not come immediately on refitting the honed-out cylinder, although that had solved the seizing up problem (hooray). The simple Villiers carburettor (originally ‘Mills’ until that firm was bought out) is fitted with what looks like a filter, but contains no filter element. It also turns the rearward-facing inlet into a front facing one – surely not to obtain free supercharging! Fiddling with this, even to the extent of trying to insert some filter gauze (not easily done as the item is welded up) produced no significant improvements. One thing missing, which usually features on Villiers and other two-strokes, is a strangler, and PUB has generally found these to be needed for cold starts (especially on older engines with less than perfect crankcase seals). To the rescue came B44 ‘Clever’ Clive who faked up a double-threaded adapter incorporating a strangler contoured exactly to the original item. It is a really neat and impressive mod. But the next trial revealed excessive four-stroking. PUB had, however, done two things at once, messing with the needle positioning springs again as well. Silly girl.
The Rex’s Villiers carb is a ‘2 lever’ device, which features a ‘weak-rich’ handlebar lever above the throttle lever. As referenced in a previous column (RC170, June 2018), this second cable compresses or releases a relatively strong spring above the needle, thus raising or lowering it against its own weak spring. The drilling is small, so finding a strong spring of sufficiently small diameter is not easy. Neither is getting its length right – too long and it becomes coilbound before achieving rich (so bad starting), whilst too short fails to push down for the weaker running setting. This is a fairly critical thing to get right (she now knows!), and a finger up the inlet revealed that movement of the handlebar lever only produced corresponding movement of the needle over a part of its range. Yet another try was required, after rooting around for another suitable donor item in her springs box. This time the strong spring was shortened just a little at a time until satisfactory control of the needle appeared to be achieved. The improvement was significant, and the four-stroking finally cured in the fully weak position.
Whilst this was all progressing, PUB attempted to investigate the automatic lubrication system as well – whilst doing the test running on with a petroil mixture just to be sure. Sadly no easily visible oil drips could be seen in the sight feed, but the Villiers book suggested that this was
normal and that adjustment should be for the typical blue haze from the exhaust. It also said that the tank pressurisation should be 4-6psi, a figure that misled PUB greatly until she thought about it more deeply (see later). So a replacement tank cap was made (by a certain clever and helpful person) onto which a balloon could be fixed to check – in fact why did Villiers not fit a pressure gauge themselves for owner confidence?
The first ride revealed why, though PUB did not recognise it straight away. The balloon responded in most peculiar ways, only rarely inflating significantly, and sometimes appearing not only to deflate but to actually suck down to nothing? Perhaps the system, with all its pipes, was leaking?
To check that, the balloon was fitted directly to the crankcase outlet, temporarily disconnected from pressurising the tank. Climbing up out of PUB’s drive this inflated a bit more impressively, but as she rounded the corner onto level road it deflated somewhat again. Slowly the various tests revealed that significant tank pressure only occurred when larger throttle openings were held, but disappeared on the over-run or even low throttle. Actually, this should not have been such a surprise. The ingenious system was developed specifically to provide oiling according to load, more when opened up (and lots of air gets to crankcase and cylinder) but less on light load (throttle closed and airflow restricted). So it is probably working (probably?), but any gauge would most certainly confuse the rider, if it managed to read anything at all.
In fact that Pearson Villiers book should never have included the 4-6psi figure. A little thought reveals that 6psi nominally requires a nominal 1.4:1 primary compression ratio
(0.4 x atmospheric pressure = 6psi). Such a compression ratio usually requires a lot of effort to achieve – unlikely in a 1927 Villiers roadster engine. Moreover, the lubrication details (see RC165, January 2018) reveal that the sight feed contains a ‘bleed hole’ in order to prevent the oil siphoning into the crankcase when the engine is stopped. The bleed hole size is stated to be critical; too small and it may block, and too large prevents the tank pressurising adequately, since there is a small, continuous, air flow through it. In fact, since not only the pumping action of the engine is ported to the tank, but so is the flow of oil down into the main bearings and cylinder feeds, then that flow is probably sucked by crankcase depression even when the throttle is closed and little crankcase pressure occurs – hence the balloon appearing to suck down. PUB now suspects that tank pressures lie more in the range of plus very little psi to minus even less psi in practice according to throttle opening. Her advice for such systems is to run with a fairly lean petroil mix for security, and play with the automatic system as the book says – for a bit of blue haze (others just suggest ignoring it and using petroil alone).
Concluding that the engine is fine and the lubrication system probably OK, it was time for the Rex-Acme to go home to AJS Mary (Rex Mary doesn’t really work, as the correct appellation would be Regina – but as she consorts with Plantagenet knights and plays ancient musical instruments as a hobby perhaps ‘Medieval’ Mary would suit). Once the bike had been unloaded off the trailer MM togged up and tried the machine down the road. Cold start: OK. Seizures: none – cured (they happened within sight of home previously). Hot start: easy. Cool start: better than PUB had expected. Big smiles all round, and it was time to go inside for a cup of tea and to enjoy the glow of success.
Then it became time to put the bike to bed in its garage and it all went pearshaped – the tank paint was lifting badly. The question was why now, since the tank had contained petrol for some time. At present only the shaking up from the delivery trip is on offer as an explanation. In fact why has it happened at all, because this is the second type and application of ‘ethanol proof tank sealant’ that has failed. Clive is distraught, having worked so hard on it, and even more so now because his own tank, sealed some time ago, has mysteriously also started to lift its paint and leak. PUB would be interested to hear reader successes and failures with the various sealants advertised as ethanol proof. The Rex-Acme stayed with Mary, but the tank returned with PUB, for a solution that still has to be invented.
It would be tempting to go to bed, and not get up again until spring returns, but the RC deadline (and its fearsome Editor) approaches…
RealRacers at Brackley: a 600cc ValMoto Triumph, ridden by John McGuiness in the 2003 TT, alongside a Crighton rotary Norton fielded in the UK 1992-4 sponsored by Duckhams
Above: Would you like to see this sort of action in your local High Street? Well move to Brackley in Northamptonshire and you can
Above: The Brackley Motorcycle Festival may only ‘demonstrate’ interesting and race machinery, but Sammy Miller, here on the museum’s Gilera four, only knows how to ride slowly in muddy trials – tarmac brings back his GP racing head
Keeva Hart and Sophie Goodall’s entry tackles the soapbox course. Compare their well sculpted ‘Naphill Railton’ with the famous Brooklands Napier Railton pictured elsewhere
Above: The Great Dorset Steam Fair is a fantastic, and huge, event. There were over 500 steam engines (traction engines, rollers, etc.) including more Showman’s engines than PUB knew existed. There were many other attractions, including a small display of motorcycles. However, this is a Dutch visitor’s own amazing motorcycle parked outside – but PUB does not know any more about it
Left: There is a popular little yellow and red kiddy-car (Little Tikes Cosy Coupe), one of which currently features on TV. At the Kop Hillclimb a full-sized one took to the hill – but probably not with the kid pictured here driving
The Brooklands ultimate lap record holding 24 litre aero engined Napier Railton was once again in attendance and ran up the hill at Kop. Compare with the Naphill Railton soapbox
Strangely, Villiers (or Rex-Acme) fitted the rearward facing carburettor with a forward facing cowling open to dust and rubbish. Certainly not for speed-induced supercharging. There is actually a newly installed strangler, but so neatly has B44 ‘Clever’ Clive added it that it is almost invisible
More ‘blue haze’ generators, a line of Scotts at Kop between motorcycle sessions on the hill
The Villiers 2-lever carburettor slide. Note the weak spring lifting the needle, and the stronger spring on the cable end depressing it when released. These all live in the centre hole, retained by the hexagonal brass ferrule (which rises and falls through the carb top when the throttle is operated). It is quite tricky to get those spring rates and lengths right, without which starting or running will suffer
A dummy oil tank cap was used with a balloon to try and verify that tank pressurisation and the Villiers Automatic Lubrication were working properly. It was not entirely successful (see text) for the Villiers oil system is truly mysterious
With suspicions about whether the crankcase porting and pumping were working properly, the balloon was transferred directly to its exit pipe. It promptly indicated pressure – but only with the throttle well open, deflating again with lesser openings. Nor is there any leak back through the main bearing bushes, for this picture was actually taken after the engine had been stopped, and PUB had gone to fetch a camera!
All’s well on the Western Front – the Rex-Acme returned to its home in the nether region bordering on Wales, and clearly running satisfactorily. Just look at that smile, which lasted long enough for a celebratory cup of tea (Mary and PUB are English after all) before…
…gloom and despondency set in. The twice sealed Rex-Acme tank is unsealed again, and the paint lifting. What is the RC readership’s (recent) experience of magic epoxy tank sealants?