It has been a ‘Good news Bad news’ sort of month for the Rex-Acme, PUB, and AJS ‘Me­dieval’ Mary.

Real Classic - - Jacqueline Bickerstaff -

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?

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