TRIUMPH BONNIE BUILD
A pre-unit Bonneville with a duplex frame? It’s a rare one, then. Rob Davies reports on a rebuild
A pre-unit Bonneville with a duplex frame? It’s a rare one, then. Rob Davies reports on a rebuild
Mick Holmes is one of those all-round decent guys who not only gets great pleasure from restoring classic motorcycles, but he also tell his wife how much he spends on them. Whatever next? So it was most fortuitous that I should meet up with him only a couple of months after he commenced his rebuild of a classic 1961 Triumph Bonneville.
Mick has an impressive collection of classic metal, including a very tasty 650 Super Rocket and a Rocket Three – the early one, I hasten to add. But in the autumn of 2015, just when he was hankering after a project, he came across an unloved Bonneville at the Stafford Show being sold by Yeomans Motorcycles, a company established back in 1972 that deals especially with classic bikes and parts.
For many, this model is the ultimate choice, having become one of the most soughtafter models, with its sky blue tank and the chrome headlight which thankfully replaced the earlier headlight nacelle. To beef the bike up, it also had a twin downtube frame – which helped take the high speed wobbles out of the previous incarnation, though it must be admitted that our American cousins did often take the frame to breaking point with their off-road enthusiasm.
Personally I must admit to having mixed feelings about the 1961 pre-unit model with all its post-war ‘blackness’, the poor build quality of its handlebar clamps and general fittings, but maybe that’s all part of the attraction? Nevertheless, as you are no doubt well aware, desire or demand, call it what you will, has outstripped supply, so these bikes, even if they are in dog rough condition and haven’t run for several decades, are going for a premium. You can of course try and haggle with the seller, but it won’t get you very far, so if you want one, really want one – you have to man up, as they say, and pay the vendor what he asks.
Mick is a fairly wise investor though, had already done his mental arithmetic, and had rightly guessed that a full refurb including the cost of the basic machine would cost around £11,000. This figure turned out to be well under the total spend, but Mick’s goal was never to buy and sell for any possible profit (there was none) but to have a first class restoration. Mick wanted the Bonny to be a permanent member of his piston powered stable, to enjoy riding it and taking it along to he shows.
Of course one has to ask the all-important questions about the bike’s provenance before purchase. Fortunately with this example the engine and frame numbers matched and had been authenticated by the relevant Triumph club. Having said that, no one knew when the bike had run last – it was probably years ago – so there were no guarantees about anything. There were no clocks either, and genuine clocks – old ones – are also being sold at a premium. These sort of things need to be taken into account when the emotions of raw desire are running high and your heart is trying to rule the head and wallet.
But lo, the bike was transported to Mick’s garage, and the process of stripdown and assessment began. It was speedily noticed that the mudguards, which had initially looked OK, were not OK. They were possibly off a Tiger 90, but didn’t truly follow the curvature of the wheels and tyres, so that was a pair of scrap bits to kick off with. Also, an early owner had understandably changed the original Monobloc carburettors for the
later Concentrics; so they would need to be changed back. And the manifold was a botched job, as was a cutaway section at the rear of the cylinder head. Not good news.
Mick is philosophical about such things, and several suppliers that could replace these valuable items were contacted. For instance Ace Classics, based in North London are useful for parts, as are Surrey Cycles, who specialise in Amal carburettors, and they could supply a pair of brand new Monoblocs. Tri-Supply, another longestablished Triumph supplier, was also contacted, and parts for the front forks and front and rear hubs were ordered.
Meanwhile, there were lots of jobs to get on with, parts to be sourced and ordered, and the stripped frame, cast iron barrels and outer hub components could be cleaned and powder coated. Seals and new black rubber gaiters for the forks came from Tri-Supply, but after looking closely at the stripped fork stanchions Mick decided that there was too much pitting to them, so they were replaced. Barrels and head went off to Harthill’s of Bilston (another old established Midland company) for re-boring and new pistons, while other bits that need to be engineered – including the crank – went to another Bilston engineering company, E & D. All tinware was dispatched to Dream Machine in Long Eaton, who specialise in high quality paintwork. They aren’t cheap, but they do a fabulous job.
Then came the search for replacement clocks, and Mick was pointed in the direction of Ashley Pople, a guy who has long experience with instrument replacement and repair. A reconditioned speedo, new rev counter plus timing cover – where the tacho drive is taken from – was going to cost £460, but that was the two clocks sorted. And then It was a case of sitting patiently and waiting until all these lovely items arrive in the post, and your eager fingers fumble in anticipation while getting the package opened. You then stand and turn the items over and over in your fingers, admiring every
surface lovingly, looking eagerly forward to the day when they can be fitted to the bike.
When I arrived at Mick’s workshop in a dreary February, the frame and wheels had come back from the powder coaters and they were together. When you look at the pictures you can quickly see how much black paintwork there is on this early Bonneville – have I mentioned this before? Not just the frame and swinging arm, but footrests, top and bottom yokes, rear shocks, brake lever, rear drive sprocket and headlight brackets too. So thank goodness that the design was to some extent brightened by the classic shine of chromework to the exhausts, headlight and tank badges.
It’s at this point of the rebuild that I should mention the advantages of being a member of a motorcycle club, for within a club there are always guys who have talents and abilities that you don’t have (and vice versa). In this case a member had the ability to make stainless steel bolts and nuts, and Mick gratefully took full advantage of these skills.
I called to see how things were progressing half-way through July. Mick had indeed been busy and there were lots of boxes of new bits simply crying out to be bolted to the Bonny, but there were also hold ups too.
RD: I see you have the bottom end of the engine built up and in the bike, but where are the barrels?
Mick: ‘Well, that has been the problem. The original engine had already been bored out to its maximum at 60 thou, so sorting the barrels out has somewhat held me back. It’s possible to source another set of barrels – and Triumph barrels are easier to get hold of than say BSA A10s – but it means more money. Reproduction barrels can look and feel the same as original, but often they don’t have an air passage between the two cylinders. In the end Harthills of Bilston sourced a set that still had room for a last rebore, and 9:1 pistons were fitted. An extra thick copper head gasket helped to reduce the compression ratio.
‘I’ve decided to have the old barrels sleeved and then bored to standard. This will make it much easier to buy a set of pistons, though whether I’ll fit the regular 8.5:1 pistons or lower compression flat top pistons, I haven’t decided. With today’s fuel, the advice seems to be that engines will run better with a lower compression ratio; but I’ll make a decision on that later.’ RD: The cylinder head looks OK too?
Mick: ‘ Yes – looks like new, doesn’t it? If you remember, the head was damaged near the exhaust flanges, so that had to be repaired with aluminium welding, and after being polished up it’s impossible to see where the repair is. After that I had new valves ground in and I fitted the new valve springs. As you know, this is an eight stud head, and they were prone to cracking where the bolts go through. As you can see there isn’t much metal between the bolt hole and the combustion chamber. The common modification is to have steel sleeves driven into the stud hole.’
RD: Let’s talk improvements for a moment. I see you have an entirely new clutch, and an SRM outer clutch plate?
Mick: ‘I didn’t really want to put an old clutch back onto what is going to be basically a new bike, so new plates with a better material than the old cork were the order of the day. The SRM outer compression plate has a rather neat little needle roller bearing at the centre which helps to keep the clutch square as it’s pushed open by the pushrod, and at the same time avoids clutch drag. And then at the back of the clutch there’s a bronze bush that helps everything to operate that bit quieter.’
When I returned to view the progress, almost a year had gone by since the start of the build. Forget what I said earlier about the ’61 Bonny not being an attractive machine. I had only been looking at photos of this particular model, but now, looking at the almost finished bike in the flesh I was truly struck by its balanced beauty. The human eye is amazingly good at weighing up proportions and quick to notice what seems out of place or unbalanced. I had to admit that the bike
in front of me had a well-balanced look from wheels and tyres to engine and gearbox. The paintwork to the tinware and fuel tank was exquisite – especially that gorgeous glossy pale blue to the upper surface of the tank. Nevertheless, Mick had hit a serious problem – but we will come to that later. For now we walked around the bike as it stood on the bench and admired its features.
The timing case, which had previously been cracked, was now repaired and polished to the point where you could not detect the welded repair. The oil pressure button looked equally shiny, and Mick related how the bronze bush just inside the case had been replaced by a superior SRM job which included a rubber seal that should help maintain the oil pressure to the big ends.
Mick had hovered over the question of whether to have the original primary chaincase repaired, but in the final analysis he had bitten the bullet and bought a new inner and outer case. After all, they are only £400! But they did look great. The new carbs, 376 Monoblocs from Surrey Cycles, with their shiny attendant taps looked fab, but they both sported the float chambers to the left of the main body, giving a slightly off-balance look. Maybe you have seen these carbs with left and right float bowls in photos, and they do look the part, but Mick had been unable to obtain any of these.
The front stainless wheel had come with the bike. Unfortunately the rear wheel, though in excellent condition, was 19 inches and not the correct 18-inch rim. So a new 18-inch rim had been purchased along with the correct tyre. It is apparent that Triumph had chosen the 18-inch to enable fitting a larger cross section tyre, therefore getting more rubber on the road. Let’s face it, this is a powerful bike and the more grip, the better.
The brand new seat from Leightons in Birmingham looks great, and it had the ’61 black top. The later ’62 seat would have a grey surface and a black side cushion. Going over to the engine, I could see that the head had been repaired and vapour
blasted to give it that brand spanking new look. The head had been completely renovated (Harthills in Bilston) including new rockers with mushroom tappets and new aluminium adjustment caps – all very splendid. Mick had fitted a competition magneto from Tony Cooper in Blackheath, West Midlands. Apparently the comp mag, with its red badge, had improved windings and a new auto advance unit – about £500.
New handlebars from Tri-Supply were lusciously coated with chrome, as were the new light switch and horn, finished nicely by stainless bolts and adjusters, all made by club member John Williams. The original headlight had been re-chromed. The gearbox had had come with a very worn mainshaft so that had been ground and a new bush fitted.
‘So what has been the biggest problem?’ I asked tentatively.
‘ These exhaust pipes’, replied Mick with just
a tad of frustration in his voice. ‘I’ve bought two lots so far, and neither fit properly or look right, even though both sellers – I won’t mention any names – insisted that they were original patterns. Well… they are not.’
We looked meditatively at the two very different pipes that hung limply from the exhaust stubs. A very nice chrome pipe was loosely fitted to the right cylinder, while a plain dull steel pipe hung from the left cylinder. Mick held a mate to the chrome pipe in his hand. ‘When you put this other chrome pipe in place it hangs lower than the right pipe and looks awful. And there is supposed to be a swan neck bend at the rear to mate up with the Burgess silencers. But, they just won’t fit. It’s the same for these steel pipes, which I hoped would be coaxed into place and then get chromed; but they are dissimilar too. And until I can sort this problem out the bike won’t be finished.’
This is an occasional problem when you come to restoring a machine that is some decades old. Suppliers will insist that their product will fit, whether it be a set of pipes or a seat bracket. So my advice is, always get a receipt, because if you hand over cash, and I am sorry to say this, some suppliers are unscrupulous enough to tell you when you return the part that you didn’t buy it from them. As for the badly fitting pipes, I happened to know a local guy who specialised in cutting, welding and re-chroming exhaust pipes so well that you couldn’t tell where the alterations were. I gave Mick the address, and await the finished result. You see that I can be helpful occasionally!
The only other real teething problem with the Bonny was with the kickstart mechanism. What could be causing the kickstart lever to lock at the top of its stroke? Surely it couldn’t be the quadrant and spring, for they were new, as were all the bearings in the gearbox. Usually, with a problem like this, the poor restorer stares meaningfully at the mechanism and operates it a thousand times until he gets a migraine from all the concentration. After lying down for a while it’s then time to phone a friend – hopefully one who will be able to put his finger on the answer…
And that, dear reader, is exactly what happened. A club member who had also encountered this annoying phenomenon had discover that within the ratchet mechanism is a steel sleeve that can either wear with use, or – as in this case – have a few thou of play due to poor production methods. Once again we come across poor aftermarket parts. A new part was machined, fitted, and lo and behold, no more locking of the kickstart. Time for a ride?