It turned out that the bike had been taken apart ten years ago and the restoration work was limited to painting the frame in red primer, the other bits had an aluminium or ferrous oxide finish. The machine was almost complete, but many small parts and nuts & bolts were missing, presumably by being carefully stored in the previous owner’s dustbin sometime in the distant past. The main mechanical problem was that the pistons had been left in the barrels unoiled and open to the air with the inevitable consequence of seizing solid in the bores. I had noticed this when I bought the bike, so can’t really complain, but I’d been stupid enough to believe that soaking them with penetrating oil would soon free them.
I knew that stuff had "Rocket WD40" written on the can but he must have been a real optimist because a Saturn V on full thrust wouldn’t have shifted that lot. In desperation I nearly resorted to sawing through the piston skirts, thinking that they'd be cheaper than new barrels, but after further thought I tried a scientific modus operandi based on thermodynamic and kinetic principles (a blowlamp and a sledgehammer) which solved the problem in a moment. From this experience I was able to postulate a First Law of British Motorcycle Mechanics: the incidence of successful job completion is directly proportional to the amount of force applied at any given time.
It was at about this time that I noticed the slight identity crisis my machine was suffering. The engine was definitely a 500cc T100A, but the rest was, or had been, a 3TA 350. So what, I hear you cry, same difference innit. Well, yes, almost, but at that time these were the only bikes in the known universe fitted with 17” wheels, apart from mopeds, which meant that the only tyres available were Avon SMs, which are OK on sidecar outfits or the edges of jetties but pretty useless anywhere else. At that time classic things like bathtubs were thought of as superfluous junk fit only for scrap-yards, which was fine until you had to sort out the headlamp and speedo mountings or mudguards to match the curvature of those silly wheels. Later models lost some, then all, of the surplus tinwork and gained bigger wheels.
The loss of the nacelle meant that one of Joe Lucas’s finest achievements of the era, the combined ignition and lighting switch, needed a new home, provided by a chrome headlamp with a nifty removable panel which I found, completely by chance, in a local car breakers. Unfortunately, this was stretching things a bit far (literally) for the wiring loom’s 19 connections to the switch, which fall out at inopportune moments. More hassle resulted from Triumph’s use of one inch handlebars, it proving easier to fit collars over these and attach easily available levers, switches and twist grip rather than hunt for originals.
The engine rebuild employed the old barrels without a rebore, despite the fact that they looked a bit moth-eaten where the pistons had seized up for ten years - who cares about a bit of blue smoke? A Honda clutch pushrod was used instead of the original which had disappeared, a few ball bearings made up the length. A bit of new oil was all the gearbox needed, which is lot less than the cylinder head and rocker boxes; major transplant surgery was required. The pushrod tubes were suffering from that well known dodge of adding extra oil rings to stop the oil pouring out - all it actually does is to bend the sealing surfaces and make them leak even more - it can even distort the head and blow the gasket. Anyway, it soon began to look like an engine again and I levered it into the newly painted frame.
The exhaust system was the next, and I hoped final, problem, this turned up in MCN for the huge sum of £2. This really wasn't such a bargain as they were for the 350 and I had to ride 40 miles on a CD175 with the exhaust tied on the back with a piece of string. The difference between a 350 and 500 system is only that the latter has larger pipes, although the ports are actually the same size, so all you have to do is remove the collar that the 500 had over its exhaust stubs - although this wasn’t immediately obvious at the time because the collar was rusted into the stub making it look like one piece. To celebrate completion, a new seat was bought but the effect was promptly spoiled by mounting it on hinges made from bicycle levers!
But would it run? Not a splutter. A peek inside the carb revealed a float bowl full of gunge despite the fact that I’d cleaned out the tank. Once cleaned it started first kick, much to my surprise. It even ticked over reliably after a few minutes. Single carbs do have their advantages, the same job on an eighties superbike would probably take about three hours fiddling with air-filter boxes and things.
First outing was for the MOT test, which, of course it failed. "The number plate must be mounted at an angle of no more than 5° from the vertical; yours is at least 15..." As I'd somehow forgotten to pack my theodolite or protractor that day I couldn’t really argue with him, so I just went home and did as he said. The next day I, and a large bag of tools, went for a test run to see what would break or fall off first.
Once I’d educated my right foot to change gear, I started noticing things about the bike. Amazing, 85mph and still only in third gear - of course the true speed was more like 45mph, the local con-man (as I’d suspected at the time) had sold me a speedo drive of the wrong ratio. It was fascinating to watch the way that Smiths Chronometric instruments moved in little jumps around the dial. The expected blue cloud accompanied acceleration but the engine sounded very noisy (even for a Triumph). This, I thought, was due to over-advanced timing - one of the benefits of distributors is that you can undo a single screw and play with the timing whilst the engine is running (yes, I know CD175 owners can do the same to their points backplate, but we’re talking real bikes here). The engine became quieter and smoother.
Over the next few hundred miles the bike did around 75mpg and leaked negligible oil, although it made up for that by burning lots of the stuff. Reliability was OK save for the electrics, thanks to the rampant spaghetti that was supposed to be a wiring loom. Sometimes the ammeter showed a charge, sometimes it didn’t, for no apparent reason. When this happens a fully charged battery will last for a surprisingly long time until the lights are turned on... I can recall being stuck with a dead engine on a deserted and dark country lane. I was trying to figure a plan of action when, as if by magic, a rider on an MZ appeared. He was obviously an ex boy scout because he appeared to be carrying enough electrical equipment and tools to rewire a house.
Jump leads from his battery (also 6V) got the 500 going again and its half hour rest had persuaded the alternator to start working again. To this day, I never say anything against MZs or their riders. The cure for all these problems is to fit a later, two wire, 12V alternator and Zener Diode. As well as producing enough energy to power decent lights it greatly simplifies the wiring circuit by removing the switching of generator coils. The brave could also get rid of the ammeter (the vibration will make it fall to bits, anyway).
If you do use this system, make sure the Zener Diode is mounted on a proper heat sink and earthed well - under the headlight is the best place but don’t rely on the head bearings allowing a good earth. This component functions by turning surplus power into heat, but if it gets too hot it will short out. This should blow the main (only) fuse and leave you with no electrics. I say should because if you have, by chance, ‘temporarily’ replaced the fuse with silver paper, what will actually happen is that a small fire will start under the seat, If you’re quick you might just be able to stop, open the seat and rip the battery leads off in time to avert a major conflagration, just at the point when you're wishing you hadn’t saved three quid by taking out Third Party Only insurance. This is all purely speculation, of course, since I certainly wouldn’t be so stupid to replace fuses with silver paper, oh no...
After that episode, I mean after considering that hypothetical possibility, other breakdowns seemed tame. Like the time the front of the headlamp fell out and dangled on the end of its wires reminding me of those eyeballs on springs that you get in joke shops. I wasn’t laughing much at that moment, however, because I already knew what the top of my mudguard looked like, but the view of the hedge I was about to go through would have been more useful.
I kept the Triumph for a couple of years and, although it was never a bike that you’d feel confident about riding on a world tour (Ill leave that to Ted Simon), it did have a certain bodgability which meant that it could always get you there somehow. I didn’t fall off it, probably because the brakes were too weak to lock the wheels, but came pretty close on occasions when dirt got in the scavenge side of the oil pump (when this happens the crankcase breather sprays oil onto the back tyre).
I sold it because I needed a low maintenance, hassle free means of transport, what I actually acquired was an unreliable, expensive to run, disaster called a Honda CB500T, but that’s another story...
R. Ker