In Bal­ance

Some­times the ob­vi­ous is clear to all around – ex­cept for the one who needs to know...

Classic Dirtbike - - Contents -

Cap­tain Ob­vi­ous is a UK ad­vert char­ac­ter who points out the ob­vi­ous to hap­less souls… He was needed in the work­shop.

I’d be sur­prised if I’m the only one who has missed the glar­ingly ob­vi­ous un­til it’s pointed out or an­other un­re­lated task re­veals what should have been clear from the out­set. Thank­fully such in­ci­dences are rarer than they used to be, or maybe I’m at that age where I can’t re­mem­ber them. The rea­son for the sub­ject of this is­sue’s col­umn oc­curred when putting the bat­tered rem­nants of the project Tri­umph to­gether qui­etly one evening. Things have moved along quite rapidly af­ter many years of lit­tle or no change and the need to free up bench space for other work caused an ex­tra flurry of ac­tiv­ity.

Tri­umph en­gines are not par­tic­u­larly com­pli­cated so few prob­lems were en­vis­aged and those that were likely to arise were ex­pected to have been caused by the length of time this project has been on the go and the num­ber of house/work­shop moves it has had to con­tend with. Ergo, these prob­lems were con­fi­dently ex­pected to be of the ‘now which box did I put that in’ or ‘is that on the shelf here, or in the stor­age fa­cil­ity or my mate’s garage’ sort of sce­nario. A late game plan change to as­sem­ble all the bits I have on hand and then ac­quire the bits I haven’t sort of speeded things up and I ad­mit some bits which rightly should have gone to the scrap bin have found their way back on to the bike. Be­fore you all start writ­ing in there is no in­ten­tion to use the mo­tor­cy­cle with these bits but rather they serve the pur­pose of hav­ing all the boxes emp­tied and a way will be seen to progress with new bits… the gear­box sprocket is one such part which shouldn’t be any­where near a mo­tor­cy­cle, talk about hooked teeth… We all know, or should know, such a sprocket would make short work of a new chain so it’s lucky I don’t even have an old chain.

As this re­build is doc­u­mented reg­u­larly else­where in the mag­a­zine and our sis­ter pub­li­ca­tion The Clas­sic Mo­tor­cy­cle, I don’t in­tend to go too deep into the bike in this col­umn as well, suf­fice to add the com­po­nent parts were all ar­ranged on var­i­ous parts of the bench so they could go into their re­spec­tive places – the swing­ing arm spin­dle greased and ready to drive in through the lug, spac­ers and shims ready, then the gear­box clus­ter and other com­po­nents which go to make the gears sorted. Lit­tle dis­rup­tions such as the ab­sence of the cor­rect length studs and screws were sorted by rum­mag­ing in the box of old fas­ten­ers. Even the fact the se­lec­tor plate wouldn’t line up with the rollers on the se­lec­tor forks at first be­came ob­vi­ous un­der in­spec­tion and was quite eas­ily solved – two cogs were the wrong way round on the layshaft and had been since the bike was stripped. Once the cogs were put in cor­rectly the clus­ter ver­ily jumped into place in the cast­ing and we even had four gears en­gag­ing.

Miss­ing from the project and again some­thing ob­vi­ous is one half of the Tri­umph forks. This is less of a prob­lem than it may seem, as my in­tent had al­ways been to use stronger forks in this project as the Tri­umph ones are 32mm di­am­e­ter stan­chions and even John Giles was quoted as say­ing they could wilt a bit. There are a cou­ple of sets of BSA forks to hand though and with 35mm stan­chions they’re much tougher.

Okay, it means a dif­fer­ent type of front wheel will have to go in the bike – the spin­dle mounts are knock through on the BSA but clamp up on the Tri­umph but that is fairly ob­vi­ous and a spin­dle isn’t hard to source or make for that mat­ter.

Work pro­gressed up­wards on the engine and the lit­tle plas­tic trays which have so long been a part of this Tri­umph’s ex­is­tence were emp­tied as parts were fit­ted to the engine. A rocker box was as­sem­bled from the bits which had once been in­side it, a new spin­dle was needed be­cause the old one was long gone, oil was pumped through the drillings and all seemed well in the world. I elected to not put the pushrods in place nor their tubes as the head was al­ready sit­ting in place, bolts fin­ger­tight. So, I thought I’d just put the rocker boxes on the head and screw them up fin­ger-tight too. On the smaller unit en­gines the rocker oil feed comes into the engine via a thin tube with a banjo fit­ting on ei­ther end. The rocker bolt has a re­lieved sec­tion to al­low the oil to flow into the box it­self and this bolt slides up un­der the head and forms a third fix­ing on the front of the cast­ing… or it does if the lug on the cast­ing is there…

The ex­haust box fit­ted as it should and once I find the domed nuts it will fit in place no prob­lem but the in­let one is miss­ing the vi­tal bit on the head. It should have been ob­vi­ous to me but it wasn’t. In my de­fence, where the lug had been was com­pletely flat, so has at some point been cleaned up with a milling ma­chine as no trace of the orig­i­nal lug is there. A re­view of sev­eral months of pho­to­graphs clearly show the lug is miss­ing and yet what is glar­ingly ob­vi­ous now had been missed for good­ness knows how long. Luck­ily I have a cylin­der head which is scrap but has lugs and fins on it to re­place the miss­ing items.

My welder will be pleased...

…my in­tent had al­ways been to use stronger forks in this project as the Tri­umph ones are 32mm di­am­e­ter stan­chions…

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