Triumph unit twin rebuild
It would be nice if there was dedicated time to do these restorations, but this is real life…
With a project such as this Triumph, there’s a lot of freedom in choosing parts. The bulk of the machine consists of parts I’ve acquired over a period of years and which have been lying on various workshop shelves. To be honest, had anyone come into my workshop or garage at any time and asked ‘Have you got a…?’ if I had then the bits would have gone.
They didn’t, this leads me to believe one of two things: first, the bits I have are fairly
Words and photographs: TIM BRITTON
common, second, the bits are unlikely to be worth a fortune and the conclusions drawn from this are I might as well chuck them all together and build a bike from them. If any reader thinks ‘ooh that’s a good explanation to use…’ and runs this thought past their other half when put on the spot, don’t blame me if you have salads for a month for tea…
Said bits – or the early ones at least – arrived with me in 1981 when I got tired of rebuilding the wreckage of a Norton
Commando engine – three crankshafts in three months, with associated damage; in those days, Roger Myers at RGM was still just off Bensham Bank in Gateshead and I almost had a reserved parking spot outside his small shop. Still, something had to be done, and in those days the Evening Chronicle still had a massive classifieds section, and there, one evening, was a notice selling a 1961 Triumph, all in bits… with the legend ‘all there…’ in the advert.
There may be enthusiasts reading this
who have viewed and purchased such projects and everything was there, although there will be many more who found as I did.
I’ll allow the bulk of the bike was in the several cardboard boxes and two plastic buckets, so the bits were hauled home. In those days, I had a big enough place to lay everything out and tick it off on a parts list purchased from Bruce Main-Smith. Once all the bits had been identified as ‘1961 pre-unit Triumph’ there were other bits left over, which were clearly Triumph, but not of pre-unit origin. Those were the beginnings of this little 350.
I have to admit to several attempts at building a bike from these bits and most were stalled for a number of reasons, mainly to do with other bikes needing the time and money. There was a point where it seemed merely thinking about doing something on this bike caused a problem elsewhere on one of my other bikes. Still, things did progress a little and a stock of bits built up, until I’m at the current state of build where the bike is together, looks like a bike and all the bits which I have little ability in sorting can no longer be put off.
An oil tank has been created; or, more to the point, a former is made and some alloy cut to shape for someone else to weld. I know, one of the nice things about such a project is the acquiring of new kit and skills… welding isn’t something I would ever do enough of to become proficient, so the tank is currently still in kit form, but sitting in the welder’s workshop rather than mine.
Oil tanks need various fittings to allow the oil to do what it does on a four-stroke engine… there needs to be some way to pour the stuff in, some way to let it out – no comments about British bikes having a self-changing facility for oil please – when it’s dirty, a connection for the engine feed, a breather so the tanks doesn’t flex and a
return feed with a spur for the rockers. It’s this last bit which is causing the delay at the moment.
A ‘proper’ oil tank for a Triumph has the return feed built into the tank – it is little more than ⁄in steel tube with a ⁄in spur tube, which allows a feed to lubricate the rockers. As this project has used an alloy tank fitted to my BSA B40 trials bike as inspiration, I wanted the fittings which were used on it. The tank was from a range sold by Neville Lewis at Surrey Cycles and the oil tank has a neat return fitting, which screws into a boss on the tank and I thought I had little else to do but buy one… oh, I should have known… all attempts to locate this fitting have drawn a blank, even contacting the original wholesaler who supplied them has not turned one up.
The annoying thing is on the day I dropped the tank kit off at Audit CNC to be welded, MD Ossy Byers had been given a similar tank to repair and the self-same fitting I need is missing from it too. The search continues, though options include making a steel tube fitting and seeing what else is out there under the ‘miscellaneous fittings’ blanket. Problem with looking at such things on the internet is the search parameters are vast and typing ‘oil tank fittings’ brought up all sorts of things from vast unions for oil tankers to household heating oil tanks… so if any reader has a this-is-what-I-used answer, then I’m all ears.
One thing sorted for the tank is mounting rubbers. I queried what sizes were available and ISDT teamster John Knight came up with the rubber mounting blocks for a KTM enduro speedo. Nice neat things which will be used to provide some flexibility to the tank mount and prevent vibration causing issues.
This has left a bit of time to sort out missing bits such as one handlebar clamp, various bolts to the fork yokes and so on. It may cause people to question my sanity, but I’m using metric bolts when I have to use new ones. Why? They’re easily available and the bike isn’t a catalogue correct concours machine.
There are some which I have no option but to use original thread forms, like where the holes are tapped in the lower fork yoke. If the thread had been stripped I’d have drilled straight through as had been done on my B40 – no, I didn’t do it – and used an M10 bolt but a ⅜in BSF will be needed… of course, I’ve got every size BUT the right one in my odds box. Luckily, bolts and stuff are more easily found than oil tank fittings. So, an order is winging its way to The Workshop.
While searching for bolts and the like, it came to light my odds and sods box is fast emptying and the remaining fasteners in there are the rubbish which really should have been consigned to the scrap bin, but were saved for the day when I had a lathe and could turn down a damaged bolt and make a new one of a smaller diameter with
the correct thread on… if you’re thinking ‘he’s suggesting what?’ I thought it too and despite now having a lathe – a Hobbymat – I’ve never taken a scrap bolt and made a smaller one from it… much easier to pick the phone up and speak to the nice man or lady taking orders at the bolt and nut place.
Still to do is the seat. Now, I did get hold of a glass fibre kit and made a mould to form one, but this hasn’t been finalised yet. Actually, I’m not entirely happy with the shape of the mould, so am currently sorting a better shape. One issue with this is for a while the only time I’ve had to be in the workshop has been half-an-hour here, halfan-hour there, rather than a couple of days dedicated to workshop things.
While I consider myself reasonably practical and able to learn new skills, it isn’t something which happens instantly and I find going half-heartedly into something doesn’t work for me. So it is with making things from glass fibre matting and resin. There are a lot of variables to contend with, not least temperature and its effect on resins and their curing, but, while my workshop does have heating available, turning it on to make the seat resin cure quicker didn’t seem a sensible option. I’ll practice more with things and wait until the warmer weather. Until then, the seat will be a little more basic and be like the one I made for the sidecar which has turned up in the workshop.
As it is an off-road sidecar, the seat for the crew-person was a simple foam-covered pad on plywood, so badly rotten I couldn’t even use the base as a pattern. Plywood is available in the workshop, so are some foam floor tiles as found in DIY superstores. Drawing around the frame with a pencil then cutting the shape out was easy, drilling for tee-nuts was just as easy and a sharp retractable blade knife cut the floor tile. Some modern contact adhesive made short work of gluing the base and tile together and this is what I’ll do with the seat as a temporary measure.