PUB TALK

Let there be light, light weight that is! This is be­com­ing a theme for PUB, whether in her clas­sic bikes or any­thing new (with that de­sir­able but­ton). The lat­ter were on show at Mo­tor­cy­cle Live, but left her with too many op­tions

Real Classic - - Royal Enfield Interceptor -

Some­thing of a shadow is cast over the sea­son of good cheer, with the re­cent death of Bruce MainSmith that will have been widely re­ported by now. Not sur­pris­ingly Bruce was an ac­quain­tance of PUB, since he had been a past Chair­man and Vice Pres­i­dent of the VOC. He then grad­u­ated from writ­ing club ar­ti­cles to be­ing a staffman on Mo­tor Cy­cling, and was a good enough rider to be in­cluded in Ve­lo­cette’s 24 hour record break­ing team at Montl­héry. Sub­se­quently he pub­lished var­i­ous books, in­clud­ing a se­ries of Vin­tage Road Tests by Titch Allen, and man­ual pho­to­copies that are still avail­able (from the Na­tional Mo­tor­cy­cle Mu­seum). For a time he took his stall to var­i­ous shows, so many readers may have seen or met him.

Then more bad news ar­rived for Vin­cent en­thu­si­asts, with the news that Pa­trick Godet has passed away un­ex­pect­edly. PUB had known Pa­trick for many years, hav­ing at­tend­ing an early rally or­gan­ised by him in France. Pa­trick ded­i­cated him­self to the mar­que with such good ef­fect that a Godet-Egli is now a very ex­clu­sive ma­chine with a world­wide rep­u­ta­tion. His rac­ing ef­forts have put the Vin­cent name back into con­tention at events such as the Clas­sic Manx, with both Egli-Vin­cents in later classes, but also replica Grey Flashes el­i­gi­ble for ear­lier classes – a wel­come ad­di­tion to the va­ri­ety of clas­sic rac­ing. It may be no more.

Closer to home the fo­cus – prob­a­bly more ac­cu­rately de­scribed as out of fo­cus – for PUB’s span­ners this month was a vin­tage AJS, which is still not prop­erly on the road. This era of AJS is in­cred­i­bly light, and an ohv model should rat­tle along a lit­tle faster than her much loved but slow side­valve HRD. Hav­ing done var­i­ous things since its ac­qui­si­tion, in­clud­ing re­plac­ing a duff mag­neto from ‘stock’ (since re­paired and put on the shelf as the spare), re­lo­cat­ing footrests where they should be (in­volv­ing mak­ing en­gine plates), and fit­ting up a kick­start al­beit bodged with parts ap­par­ently from an ear­lier model, the bike needed a test ride. It did not start, and soon both the kick­start and PUB’s hip be­gan to feel un­happy, so a gen­tle bump was used on a nearby slope. The bike then started up eas­ily enough, but throt­tle re­sponse was hor­ri­ble, and shortly all came to a halt as the pri­mary chain escaped. There is no way to avoid the last catas­tro­phe be­ing PUB’s own fault, be­cause she was the last per­son to fit it, and the spring link had de­parted through ill or un­fin­ished fit­ting – oops.

The chain was an easy fix, but less so the throt­tle re­sponse, al­though the is­sues were clear enough. For a start, pre­vi­ous owner (a sprinter) had dis­carded the Binks ‘2-jet’ air slide en­tirely, and the throt­tle con­trol was a pe­riod ‘straight-pull’ type with hor­rific back­lash. Dis­man­tling it proved to be fairly in­volved, be­cause it re­quired the twist­grip to be slid off the bars, but as in­verted levers were the vogue in 1927 that in turn re­quired the front brake lever dis­con­nect­ing and ex­tract­ing first!

These straight-pull twist­grips utilise a lon­gi­tu­di­nal slot, some­times in­te­gral with the bars but in this case part of the slipon in­ner, and a scroll ma­chined into the outer, twist­ing, part of the twist­grip. As the

grip is twisted the align­ment be­tween the two slots moves along the bar, tak­ing the ca­ble end with it. Pre­vi­ous owner took that de­scrip­tion a bit too lit­er­ally, for it was as­sem­bled with just the ca­ble nip­ple en­gag­ing the slots, not­with­stand­ing it be­ing con­sid­er­ably smaller than ei­ther – hence all the back­lash. PUB sur­mised that there ought to be a suit­ably close fit­ting ‘shut­tle’, and that prob­a­bly not in­te­gral with the ca­ble but able to ac­cept a con­ven­tional nip­ple. So she set to to make one.

How­ever, that re­quired a pat­tern, which she did not have. This was solved with a bit of blu-tack / plas­ticine, pushed up in­side the as­sem­bled grip whilst it was off the han­dle­bar. The im­print left in­di­cated not only the widths re­quired (which could have been mea­sured) but also the an­gle be­tween them. A piece cut from some strip steel was then filed up to this shape, and drilled for a ca­ble nip­ple. Nat­u­rally it did not work first time, or se­cond, or third…

The in­ner sleeve is made of thin metal, so the shut­tle has to be sim­i­larly thin in part, and also sim­i­larly curved to fol­low the 1” bars. The thicker part en­gag­ing the scroll also has to be matched in its width and an­gle be­fore a smooth ac­tion (or at first any ac­tion) is ob­tained. It quickly be­came ap­par­ent that the fewest rel­e­vant bits should be as­sem­bled on the bar un­til they worked alone, be­fore try­ing more and even­tu­ally the whole thing plus ca­ble. Even that was fid­dly, and PUB sus­pects that a short length of slightly un­der­size bar might be a use­ful aid, the as­sem­bled grip then be­ing slid off the tool onto the han­dle­bar. But PUB has never been good at mak­ing spe­cial tools, and so con­demns her­self to per­pet­u­ally do things the hard way. Per­haps PhD stands for Phenom­e­nally Dumb?

Even­tu­ally, how­ever, it was done, and the throt­tle could be op­er­ated with fairly min­i­mal back­lash. The mak­ers ac­tu­ally added a cir­cum­fer­en­tial fric­tion spring at one end, but PUB con­sid­ered omit­ting it, as there seemed to be more than enough. Fric­tion and back­lash are the rea­sons the scroll type of twist­grip fell out of favour, to be re­placed by the more fa­mil­iar drum type which op­er­ates very freely, al­though it does flex the ca­ble.

The grip has now fallen out of favour with PUB too. Be­fore she had even re­placed the front brake lever she re­alised how much fuss a throt­tle ca­ble re­place­ment would be. Since both of her pre-1930 bikes al­ready use sim­ple lever throt­tles, she de­cided to dis­card the twist­grip, and use in­stead the twin levers that it also came fit­ted with. So all that work was for noth­ing – PhD! Those twin levers had been re­pur­posed for ad­vance / re­tard and valve lifter (the lat­ter very strange, and dif­fi­cult to use), but she had al­ready fit­ted a more con­ven­tional valve lifter lever. Look­ing out a sin­gle, left bar, lever for the ad­vance re­tard freed the twin levers for a con­ven­tional throt­tle and air con­fig­u­ra­tion. Or it would if the carb had an air-slide.

For­tu­nately the air slide is not com­pli­cated, be­ing ba­si­cally a cylin­der (ear­lier mod­els were ‘D’ shaped), but drilled and slot­ted for a ca­ble, and with a cut­away flat on the bot­tom end. That much can be seen in Radco’s ‘The Vin­tage Mo­tor­cy­clist’s Work­shop’ (a strongly rec­om­mended tome for novice and ex­pert alike), but not any di­men­sions and PUB had no pat­tern, so there was a cer­tain amount of guess­work in­volved. The slot­ting was opened wider with a Dremel, as PUB does not have much suc­cess with the old ad­vice to fit two hack­saw blades side by side for a wider slot than a sin­gle one pro­duces.

Mean­while B44 ‘Clever’ Clive took one look at the well-worn throt­tle slide and of­fered to make a new one. Bad move by Clive. A cou­ple of tries at mak­ing a blank to es­tab­lish the req­ui­site di­am­e­ter only proved

that the bore of the carb was too badly worn, and ex­pe­ri­ence has shown that a new cylin­dri­cal slide in a worn, bar­rel shaped body is worse than us­ing the orig­i­nal badly worn slide. At least a worn closed slide seals marginally well against the match­ing worn bore when the en­gine sucks but an ill-fit­ting new one will not. The so­lu­tion was to bore the car­bu­ret­tor body back to true again, which Clive bravely took on.

The Binks 2-jet does not use a nee­dle, and there­fore, it was rea­soned, the new bore did not have to be ex­actly con­cen­tric with the old. In fact since around 10 thous of wear was all con­cen­trated at the en­gine side, a bor­ing op­er­a­tion cen­tred 4 or 5 thous off­set in the same di­rec­tion would pro­duce a clean bore with the min­i­mum metal re­moval – and Clive was the man to carry out such a del­i­cate op­er­a­tion. It may not be very ob­vi­ous in the pho­to­graph, but he pro­duced a per­fect job, and then a new slide to fit.

Un­for­tu­nately, in the process of re­mov­ing the jets to fa­cil­i­tate Clive’s work, the main jet broke – isn’t that al­ways the way? This proved to be be­cause it was not orig­i­nal, but com­prised an adapter to utilise Amal pilot type jets (in larger flow size than nor­mal pi­lots). That meant a 5BA bore up in­side a 2BA thread, and that only leaves around 20 thous of metal, which broke rather than undo. For­tu­nately the re­main­der did not prove hard to re­move.

Rather than repli­cat­ing the adapter, PUB de­cided to make a cou­ple of new jets as orig­i­nal, which would be more ro­bust. The length was copied from the bro­ken adapter, as was the drilling of one item, whilst the se­cond was drilled some­what smaller in case num­ber one proves to be too rich (in the case of weak a jet can be drilled larger, al­though it is nor­mally bad prac­tice when jets are avail­able). Radco’s book was again in­valu­able, for it con­tains jet rec­om­men­da­tions for Binks, to­gether with cross ref­er­ences to Amal jets and also drilling sizes.

Does it all work now? Well, who knows, for PUB has fallen into the trap elu­ci­dated by Ed­i­tor Frank an is­sue or two ago, of de­scrib­ing in the mag­a­zine work still in progress. Readers will be told, or maybe will never be told, as there are just too

many things vy­ing for at­ten­tion in (and out of) the garage / shed.

The cur­rent and ne­glected mod­ern hack (with elec­tric leg) is get­ting tired as it ap­proaches 100,000 miles, so PUB keeps an eye open for a re­place­ment, be it a lower mileage ex­am­ple, a dif­fer­ent old­ish bike, or some­thing com­pletely new. The mo­tor­cy­cle show is the place to look for the lat­ter. Mo­tor­cy­cle Live, how­ever, tends to be based around the big, pow­er­ful, and fast stuff that ob­vi­ously ap­peals to the younger, stronger, and usu­ally male rid­ers. If that is you then the fol­low­ing will be of lit­tle in­ter­est, be­cause it homes in on the lighter and less pow­er­ful ma­chin­ery that some ma­ture mo­tor­cy­clists are now look­ing for (guess who).

In re­cent years this has ac­tu­ally be­come a more fruit­ful area of in­ter­est. The 300400cc cat­e­gory that has been men­tioned be­fore con­tin­ues to be of­fered by many man­u­fac­tur­ers (Kawasaki Ninja 400, Yamaha MT-03, Honda CB300R, BMW G310R, KTM 390), ex­cept for Suzuki. Chi­nese 400cc air-cooled ‘Honda copy’ en­gined retro styled ma­chines also re­main avail­able, with Her­ald hav­ing added one to their range, with an en­gine sim­i­lar to (but not the same as) that of the more fa­mil­iar MASH and the new JAWA 350ohc (nei­ther seen at the NEC). The JAWA ap­pears to be so named for his­tor­i­cal rea­sons, as it is ac­tu­ally 397cc like the oth­ers. How­ever, an ad­di­tional bike shown by Her­ald was their pro­posed 450cc wa­ter­cooled 43bhp ‘Brute’ model, which they claim is British de­signed and built. If that is true and it comes to pass it would be a wel­come devel­op­ment.

Bikes also hail­ing, at least in part, from China, but not based on the Honda clone, were those on the Benelli stand, and in par­tic­u­lar the new Leon­cino 500cc (Lion cub). It uses the same ba­sic 4-valve dohc en­gine as the TRK 502 that has been around for some time. Un­usu­ally nowa­days, this is stated to be a 360 de­gree twin, with a bal­ance shaft, which of­fers 47bhp from a bike of dry weight 186kg (196kg wet?), and with a rea­son­able 785mm seat height (31 inches). The Benelli stand also showed an ex­am­ple of their pro­posed 373cc sin­gle cylin­der Imperiale, but with few de­tails ex­cept a power of 20.7bhp (how­ever Morini Alan did find the seat height OK). Ap­par­ently it is in­tended as a 350cc Bul­let com­peti­tor, but surely a new ma­chine ought to try to out­per­form the com­pe­ti­tion, and in this coun­try that will prob­a­bly be the 500cc model and 27bhp any­way?

PUB did not see a re­peat of last year’s A2 of­fer­ings from ei­ther Du­cati (the 400cc Sixty two, al­though it ap­pears to still be avail­able) or Tri­umph (who seem to have re­placed theirs with a re­stricted 900cc Street Twin). But as most RC readers have full li­cences the full fat 800cc Du­cati Scram­bler is prob­a­bly of more in­ter­est any­way, and comes in at a rea­son­able

189kg wet. The new­est 900cc Street Twin is rather heav­ier at 198kg dry (around 210kg wet), OK for most peo­ple but a bit much for PUB (it is the same as the quoted weight of a Vin­cent, al­though that may be dry weight). On the other hand its 750mm seat height (29.5 inches) is quite ac­cept­able. Power quoted is 54bhp, which may seem a bit low, but the power and torque curves show that it is tuned for its bot­tom end, which should make for re­laxed rid­ing, es­pe­cially at the famed 55mph, or even street le­gal speeds. For many peo­ple the 765cc Street Triple may have more ap­peal with its 112bhp, a svelte 168kg dry weight (ap­prox­i­mately 185kg wet as it has a 17.5 litre tank), but a rather higher seat at 810mm (32 inches), but it is in no way ‘retro’.

The Royal En­field twins seem now to be here for real, and likely to have a sig­nif­i­cant ap­peal. Like the Tri­umph, they fea­ture a 270 de­gree crank and 270/540 de­gree fir­ing, an idea long ago pro­pounded by Phil Irv­ing but ig­nored un­til Yamaha in­tro­duced ‘cross plane’ cranks. Sadly its adop­tion now is prob­a­bly as much to do with ap­ing the sound of a Har­ley than with the de­sir­able me­chan­i­cal ben­e­fits (the pis­tons de­sir­ably do not come to a halt at the same time). 47bhp may not be much, but it is ac­tu­ally slightly more than the PUB Vin­cent, and enough for many, al­though six speeds may prove to be one more than was nec­es­sary. Weight is 200kg (plus or mi­nus 2kg ac­cord­ing to model) plus fuel, so sig­nif­i­cantly higher than nec­es­sary for A2 li­cence power to weight ra­tio (not less than 175kg for a full 47bhp). This is OK for many older rid­ers, to whom the ‘tra­di­tional’ look­ing En­fields may prove very at­trac­tive – but PUB has her heart set on lighter still.

Of sim­i­lar ca­pac­ity are the new Nor­ton At­las 650 twins: the No­mad road­ster and Ranger with a bash plate. A 270 de­gree

crank is again adopted, mak­ing this a very pop­u­lar con­fig­u­ra­tion. The Nor­ton of­fers 84bhp (enough, surely for those with not so young re­ac­tion times) in a 178kg dry weight pack­age that sounds quite at­trac­tive (190kg wet). Slightly oddly, to PUB’s eye, they have made a pol­ished fea­ture of the high up clutch cover, but the styling mostly seemed pretty good. ‘Mostly’ be­cause the quite pretty seat looked very high mounted (al­though nicely flat, rather than the com­mon stepped lay­out), and this is re­flected in the quoted 824mm seat height (32.5 inches) – nice for the taller peo­ple out there, but Nor­ton would do well to in­ves­ti­gate a low seat op­tion as do so many other man­u­fac­tur­ers.

Their front mud­guard fol­lows the ex­e­crable mod­ern fash­ion of not guard­ing against any mud, and needs to be a foot longer – but they ‘are all like that sir’, and the Nor­ton may be eas­ier to al­ter than many. The At­las looks to be a sound and mod­ern de­sign, upon which the Nor­ton re­vival might make some fur­ther progress, so wish them luck (or even buy one).

Not so long ago there was very lit­tle in the mid­dleweight cat­e­gory be­tween the mod­ern light and high power race repli­cas and be­he­moth tour­ing and ad­ven­ture mod­els, and even less with a tra­di­tional look. Now there are var­i­ous ret­ros and mid­dleweights ev­ery­where too if 180200kg qual­i­fies, but no real short­age even at lower weights than that. PUB is spoiled for choice, Ja­panese, Eu­ro­pean, Chi­nese, per­for­mance level, price, a new bike or some­thing older and el­i­gi­ble for VMCC runs. De­ci­sions, de­ci­sions. So spoiled for choice that her head spins and pro­cras­ti­na­tion wins the day.

Happy New Year!

Twist­grip outer sleeve, within which can be seen the he­li­cal scroll

The ex­ten­der fit­ted be­tween ca­ble and ad­juster. A lit­tle black tape can make it a bit less ob­vi­ous (and slightly more se­cure)

Vin­tage Binks car­bu­ret­tor body in B44 Clive’s lathe, af­ter bor­ing true and par­al­lel again. A fine job, but this is not a task for the faint hearted, or be­gin­ners

When the front brake lever had to be dis­man­tled to re­lease the twist­grip it was noted that its ad­juster was at its limit. Rather than short­en­ing by sol­der­ing the nip­ple to old and oily wire, this outer ex­ten­der was turned and slot­ted

The lower lump of plas­ticine has been pressed into the op­er­a­tive twist­grip grooves to pro­duce a rough pat­tern. Copy­ing this in steel pro­duced the up­per shut­tle, which has been drilled to ac­cept an or­di­nary throt­tle ca­ble nip­ple

Above: Com­po­nent parts of the straight pull twist­grip: in­ner sleeve with ca­ble abut­ment, outer sleeve, within which is ma­chined a scroll, outer end clamp and its mat­ing cir­cum­fer­en­tial spring

Her­ald is the lat­est to of­fer a 400cc clas­si­cally styled model, based on a Honda copy. How­ever, this en­gine is not ex­actly the same as that of the MASH or JAWA, and is sourced else­where

The main jet, on the left, broke on re­moval (which was nec­es­sary to clear the car­bu­ret­tor for bor­ing). It turned out to be an adapter, dou­ble threaded in­side its 2BA to ac­cept a 5BA Amal pilot jet. The wall thick­ness left makes the adapter very frag­ile, so the re­place­ment (right) was made more like an orig­i­nal Binks item, even to hav­ing square rather than hexagon head)

The AJS Binks car­bu­ret­tor is un­usual in screw­ing into the head, with a lock­nut. Here it is seen with newly made throt­tle and air slides, and a new, long, main jet (the pilot jet is short and orig­i­nal)

Her­ald also showed this Brute model, of 450cc, and claimed to pro­duce a healthy 43bhp. It claims to be ‘en­gi­neered and built from the ground up in United King­dom’, but is not cur­rently avail­able

As well as the new 47bhp 500cc Leon­cino 360 de­gree twin, Benelli were show­ing (but not ad­ver­tis­ing the avail­abil­ity of) this 373cc Imperiale sin­gle. With a claimed 20.7bhp it is not likely to set the world alight

The new Nor­ton At­las is of­fered as ‘No­mad’ for the road, and this ‘Ranger’ for slightly less ideal tar­mac, with a bit more ground clear­ance and a bash­plate

The ba­sic Street Twin is also the light­est of the vari­ants at 198kg dry – an im­prove­ment over the older Hinck­ley Bon­nevilles. Power is ap­par­ently down at 54bhp, but the fat torque curve says it may per­form bet­ter at real world speeds

Honda have re-in­tro­duced their Cub, a Clas­sic if there ever was one. This time, how­ever, it has 125cc, rather than the 50/70/90cc of its pre­de­ces­sors

Hot new in­tro­duc­tion at Mo­tor­cy­cle Live was the new Nor­ton 650cc At­las – this is the ‘No­mad’ ver­sion

Above: Mod­ern tech­nol­ogy at Mo­tor­cy­cle Live may not be RC ‘core busi­ness’, but BMW’s ‘shift cam’ cylin­der head is top­i­cal and in­ter­est­ing any­way. The in­let camshaft has four lobes, one lumpy pair for high power and a se­cond gen­tler pair for docile and eco­nom­i­cal run­ning. The changeover is re­ported to hap­pen in mil­lisec­onds (as it needs to, be­cause one whole en­gine rev­o­lu­tion lasts less than 8 mil­lisec­onds at the 7750rpm max­i­mum power speed). The two in­let valves are also given dif­fer­ent cam timings, which is claimed to im­prove swirl and com­bus­tion. The lower camshaft has just two lobes, one for each ex­haust valve. A pin vis­i­ble within the ex­haust cam is an au­to­matic, cen­trifu­gally re­leased, de­com­pres­sor, used by BMW (and oth­ers) to ease the ini­tial load on starter mo­tors. The boxer has 2 such heads, 12 cams on 4 shafts op­er­at­ing 8 valves. Con­trast that with PUB’s Vic­to­rian voiturette that has a sin­gle me­chan­i­cally op­er­ated valve (plus an au­to­matic one) op­er­ated by one cam (how­ever the BMW is ten times faster)

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