Triumphunittwinrebuild

Positive progress in finding sparks thanks to advice from readers and Boyer, plus a bit of extra cash in the coffers, means a kit can be bought.

The biggest bugbear for most enthusiasts is the electrical system of a motorcycle. It’s bad enough when dealing with a standard system but when wanting a specialist system for an off-road bike which will occasionally have lights fitted and there is a need to use as many bits already in the shed as possible, things become frustrating. Nor does it help when the person doing the work has little idea what he’s doing and even less special equipment. This subject has been revisited quite a lot in these pages, and one of the additional issues is the lack of investment available to spend on the project… This bit has been the biggest holdup on the project if I’m honest, and having it pointed out that if I had fewer bikes, more might work better, was an honest appraisal of my fleet. So, my BSA B40 is away to a new home and there is a little cash to buy some electrical bits and pieces for the Triumph.

Before this happens, though, I still wanted to see if the bits of electrical things I have would at least produce a current to the standard distributor, and have mucked about for far too long to try and see if they will. This happy occasion happened the other afternoon, after advice from several readers and Kevin, the tech guy at Boyer, all of whom offered a variety of advice about where I was going wrong. Thankfully, I can now move on to a slightly less frustrating problem, which merely requires me to make a decision on which kit I need for a reliable ignition system.

There was a hiccup in this some months ago, when on inspection the distributor fitted to this engine was so full of muck and rubbish it wouldn’t turn at all. This prompted me to seek out a points-type timing case, which opened up a whole new issue. Naturally, there seemed to be several different types of timing case available under the identification number assigned to this component. These differences are to do with the changes in the way the big ends are lubricated. For the distributor engine, the main bearing on the timing side is a bush – it’s what’s in this engine – and has an oil feed to the bush, and, as the crank spins, a hole in the crank boss lines up with a hole through the bush and oil carries on through the crank to the big ends. Later engines, with a ball bearing timing main, have an end feed crank which lubes the big ends… There is an interim with a timing case to the older lubrication method but the points in the side type case… All works well, as long as the oil is clean and the bush in good order, and there are many machines which have covered thousands of trouble-free miles with this arrangement. I’d go as far as to say the folklore surrounding this type of main bearing and how ‘bad’ it is has more to do with ‘bloke down the pub says…’ rather than any engineering issue, and friends with more engineering qualifications than me have pointed out

as long as the bearing material is of the correct type then all will be well. Having written about Sunbeam S7 and S8 models, which suffer from similar folklore issues regarding oil type and bushes in their drive train, it seems any problems are caused by not sticking to the manual’s advice. Okay, back to the point. When points came along and the distributor – also a muchmaligned part thanks to the ‘bloke down the pub says…’ – was consigned to the autojumble table, the newer timing cover was the same as the earlier one, but with a casting for points. Lots of opportunity for confusion and the parts manuals available to me seemed to suggest how to identify the correct one, except I managed to buy not only the wrong one, but one which had been modified to block off the oil drillings to the bearing and make it work like the old style did. So it may but I’m not so keen on the idea of such a radical modification, so went back to the distributor. 0

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3: Connecting both feed and return to either end of this T-piece and plugging in the rocker feed ensures oil goes where it should – theoretically, the bike could run like this.

1: The time has come for the blue oil bottle to go… it’s in the way, it leaks and no longer serves its purpose.

5: With two less wires to get in the way, others can be shifted easily to where they should do best work.

4: With the oil tank out of the way and a few cables routed elsewhere, for the moment there was a chance to deal with the current.

7: Potentially a crank-mounted ignition could have been bought and fitted, but deemed a bit too dear for this stage of the project. Clutch will need a review too.

6: This muck-filled instrument was the catalyst to buying what turned out to be the wrong timing case.

2: This T-piece was spotted on Autohose’s website. In non-Covid times it would have been seen on the Autohose stand at Stafford.