Look, I can see how the rather pejorative nickname "bathtub" might have come to mind, especially when you see stuff like this:
I mean, flip one of those upside down and it's the actual tinware for the bike, but still, that's a little harsh!
I prefer to think of the TwentyOne's style as being streamlined. Maybe it was to do with weather protection, or to seem more like a scooter (maybe scooters like Vespa and Lambretta were styled the way they were for weather protection)... it's all a bit pointless really. To me, these lines are fantastic and this is a delightful little bike. It is of course woefully slow, despite the press of the time claiming "sparkling" performance and "80mph". No way.
This poor bike has been patiently waiting to get back on the road since July 2013! Obviously there's a bit of work to do to recommission it, so let's get to it.
Off with those ugly mismatched tires:
The wheels came off very easily, despite the rear one not being the quickly detachable type.
You can identify a slowly detachable wheel (I guess that's what you'd call it, right?!) by the array of nuts on the inner side of the hub, as shown in the badly lit photo below:
I must say this bike surprised me for how thoughtfully it has obviously been designed: there are several details that make it remarkably easy to work on; one example being the chain guard bracket seen below, slotted so all you have to do to move it out of the way, when removing the rear wheel, is slacken a nut and the whole thing swings up out of the way:
On go a pair of amazing Duro tires from China, cheap and cheerful:
Next up was the carburetter, which in this case is a Monobloc. We have one of those on our Matchless, so this was nothing new, however I don't think I've ever properly understood just what an evolutionary leap the Concentric was when it superseded the Monobloc. The Concentric is so much simpler and so much easier to work on...
There was plenty of nasty sludge in the floatbowl, which you can just about see in the photo below, the state of the banjo filter was abominable, and all the jets had enough dirt on them that starting would have been impossible.
All gaskets and washers were replaced with new ones, so this was a good service and fairly straightforward. However, the pilot jet cover nut must have got cross-threaded at some point in the past, which I only realized when I was putting it back, and there was a real risk the whole bike would have been grounded for one tiny nut:
Luckily I was able to get the thread back in shape even though I don't have a tap & die in that size; I used a small but strong metal pick and chased the thread back until it looked right. A bit unorthodox, granted, but it worked out.
I will leave it to your imagination to picture what the inside of the gas tank looked like after 5 years decanting that nasty stuff they call
verde... suffice to say there was a real risk of permanent damage, which would have been a shame considering the tank still has the original paint from the factory. So, I've used some phosphoric acid to get rid of the worst of the rust that was forming, then handed it over to Nico who did a good job on a
Sportster tank a while back, and did it again this time.
The gas tap is very nicely made ("they don't make 'em like they used to!") and is helped by a new brass/viton washer, essential if you don't want your tap to leak. These are not always easy to find but it's worth looking around and stocking up, because they do make a big difference
This type of fuel tap uses plungers to close off the feed, and rely on cylindrical cork seals for a tight enough fit as to be effective, yet still allow operation.
The concept of using materials such as cork (or felt) must be completely alien to today's motorcyclists, who don't even have fuel taps anymore. And yet, fortunately you can still buy replacement corks and rebuild a fuel tap. You can also make one with a wine cork and some sandpaper, it will lend a wonderful bouquet to your fuel and your engine will enjoy that too. I would suggest a Primitivo from Puglia if you do this in the winter, or a chilled Pecorino from Abruzzo if it's hot outside.
These were needed not so much because the ones on the bike were nearly 60 years old, but because they had been allowed to dry up, thereby shrinking and losing their effectiveness, otherwise I wouldn't have been surprised to find them still working properly.
Renovating the fuel tap was one of those fiddly but important little jobs; unscrew the small retaining screw, remove the plunger and drive the seal holder out of the knob with a small drift. This is easier said than done, but not impossible.
I fitted a new strip of rubber finishing trim between the rear panels, it adds a neat touch and should cushion some rattling and vibration; there's also a new taillight:
We drained what was left of the engine, primary (shown below), and gearbox oil, then refilled with fresh oil(s)
While waiting for the oil to drain, I checked the primary chain for tension, it is within specs so I left it well enough alone. The workshop manual hilariously explains how to go about this:
"with the engine stopped, of course."
All fasteners were in good shape, except for the gearbox drain, which is looking a bit mangled. It went back on just fine for now, but I'll see if I can clean it up on the milling machine at uncle Fester's next time I take it out, or maybe it's just worth replacing, let's see.
A new sealed type, absorbed glass mat battery was procured, these are getting cheaper and are definitely an ideal choice for these bikes. Overall the electrics are a bit shoddy, and if I had the time I would redo a lot of the wiring and probably fit a Boyer Bransden Powerbox, or at least a solid state rectifier.
I also checked the head and barrel bolts going over the sequence shown below, and I did find a few loose items. Retorqued, they should be ok now.
All of the above happened eons ago back in mid July of the year of our Lord 2018, with the yearly "Old Irons" rally just around the corner; and yet despite getting all this done it was all pointless. The last thing left to do was refit the sump filter plug and fill the oil tank with fresh motor oil, but the plug turned out to be stripped and just wouldn't tighten, something I should have noticed right away but didn't. If I had, there might have been enough time to get a replacement, but as the saying goes if ifs and buts were candy and nuts, we'd all be riding whenever we want.
So although I had planned to take the Triumph up the mountains, it ended up under a sheet at the back of the Monolith (the
new garage). The Fastback was a viscerally wonderful replacement for the
Old Irons trip, so it all worked out but now it's time to get this blue weirdo on the road.
I ordered a replacement sump filter plug, and you can see the difference with the botched one in the photo below:
Fitment was straightforward with the bike on its side stand, good idea dad.
Here you can see a sequence of parts going back in, you can even spot a bit of flywheel...
Above, the scavenge pipe, then on go a spring and a cork/rubber washer:
Then the plug itself, with a large fiber washer and the gauze sump filter:
The hexagon is approximately a ½″ Whitworth; it snugs down properly, and should do its job... we'll find out soon enough.
Fresh motor oil goes into the tank; then, once the engine has run for a short while, the level is checked and topped up as needed. No need to excessively obsess over a precise quantity, as long as it's visibly at the right level.
Before we get to the moment of truth, we have to switch the ignition on, and I would like to bring your attention to the beautiful design of the Lucas PRS8 switch: from the adorable spade-type key, to the gorgeously sculpted light toggle (which makes a very tactile and satisfying "Clock!" sound when used), and even the provision for an emergency circuit that bypasses the battery, this is a wonderful piece.
Ignition on, chocks away...
The short-throw kickstart betrays the engine's low compression and the minimal effort required to turn it over. If you come from something beefier like a V-twin or larger parallel twin you actually have to be careful not to give it the same kind of kick, or you risk tearing this thing in half!
Disappointingly, there was no hint that the bike would start. Fuel reached the carburetter, and with all the jets and passages cleaned, it should also reach the combustion chambers.
Sparks at the plugs were very weak and very inconsistent, not a good sign.
After another LONG delay, I finally got the bike on the lift and opened up the lovely Lucas 18D2 distributor to have a look at various moving parts and connections. Everything looked present and accounted for, with the exception of the central carbon brush (number 3 in the drawing below - it wasn't there when I checked) and in fairly good condition for a nearly 60 year-old component; that said, I should probably stock up on some spare parts besides from points and condenser, which I already have.
The high-tension leads were not great, so I took my time and replaced them, a satisfying little job.
Back to the distributor, for now, I've cleaned up the brass connectors with a strip of fine sandpaper, used some electrical contact cleaner and put everything back together. Upon closer inspection of the distributor cap, I eventually found the sprung carbon brush: it turns out it's pressed into place and since it was in good shape I left it well enough alone:
Out of sheer vanity, I have these rajah connectors with cooling fins and thumb nuts, all brass, fitted to the spark plugs. They look wonderful but do absolutely nothing for insulation:
I was holding one of the plugs against the head to check for a spark as I kicked the bike over, and whilst I did not see the spark, I definitely felt it shooting up my left arm! Yeowch! I tasted purple for just a moment and then all was well again.
With the Monobloc primed and choke lever down, I started kicking it over and at first there was absolutely nothing; then the most timid, tentative little "pop!", and then finally, at long last it started... and promptly shrouded half the garden in a thick grey smokescreen cloud worthy of a racing Jawa.
Ok, to be expected since this has been sitting in a shed for so long, but that's not all: even my 4 year-old knew there was something not quite right as he pointed out "daddy look, a sticky yellow water is coming from under the bike!". Good job he noticed because I hadn't!
The sump was FULL of oil and in the end I had to shut down the engine, undo the sump plug to drain the crankcase, put it all back together and try again. This time, it was perfect.
The sound is pure 1950s Triumph: it's crisp, toned down and very dignified. This is a 350cc engine, but it sounds like a much bigger one up close; no need to worry about upsetting the neighbors with this one though, a few yards away and you can barely hear it at all.
Conveniently, the seat hinges open after releasing a single sprung knob (itself a beautiful component, with a trick up its sleeve... more on that later) and easy access is given to the electrics and oil tank.
Using a simple voltage detector I tested the battery, rectifier and surrounding wiring and all seems in order. A proper multimeter would be better of course, I'll get one at some point.
Oil return appears to be correct, and the pressure indicator on the crankcase responds as it's meant to:
This is an interesting, if quirky arrangement (a bit like this motorcycle, overall): above you can see the pressure indicator, static on the left, and during engine operation on the right; you can see the button being pushed out, this gives you visual confirmation that oil is circulating. Neat!
The original user handbook for this motorcycle reveals something that not may people may know, i.e. a built in anti-theft feature. I'm not talking about the steering lock, which is available, but rather the aforementioned seat knob. The idea was that, once parked, the owner could open the seat, disconnect the high-tension lead from the coil, close the seat and unscrew the knob. Why? Because this would make it impossible to start the machine, and the coil would be, in effect, locked away under the seat. It was then recommended that the owner place the seat knob in the liner pocket of their blazer.
So, finally back on the road, and hopefully up to the task of going to the yearly "Old Irons" rally at the end of July...
