Carburator, Carburetor, Carburettor, Carbureter, Carburetter

As you can see from the title of this post, there are many different names to indicate that mechanical device used to mix air and liquid fuel to provide an atomized spray into a engine's intake.

All are accepted spellings and all describe the same thing. Similarly, the two carburetters (that's the spelling I typically use, as it's what Amal has traditionally used) you see below are called by different names, but they are the same thing.

All photos below have the used Amal on the left and the new Wassell on the right, for comparison.

The slide at the very left of the image is an original type Amal.

When Wassell originally launched this product about a decade ago, there was a collective gasp as - surely! - this must be a flagrant copyright infringement. So many people, from the average biker to respected members of the trade were up in arms and angrily proclaimed "we will never use these!" and various abuse directed at Wassell. However, there was one clue we should have all paid attention to: they were advertised in mainstream publications, in print and online, showing very clearly the brand "Wassell" where one would typically find "Amal" cast into the body. I don't think that if whoever holds the rights to the Amal name and products had a valid patent or other right to it, that they would have just let it happen.

These are not "pirate parts" as some people call them (yet sell them!). These are not cheap Chinese knock-offs, which we should always avoid. These are a nicely made version of the Amal Mk1 Concentric.

Sure, I found some brass swarf and "dust" on some of the threads, some debris in the pilot circuit (which is very easy to clean out though, thanks to the removable pilot jet). The upper edge of the float bowl seems a little bit uneven but is reasonably flat and doesn't leak, and the float height was set correctly. The slide isn't finished very nicely, but works smoothly. The main jet was a little bit chewed up, whereas the needle jet looks very nicely made. The needle looks fine and measures the same as a genuine item (in terms of diameter above the taper), but it is probably slightly shorter (admittedly I did not measure this, I might do that in the future). It should go without saying that you should always disassemble a new carburetter, inspect it and thoroughly clean it before use, so I don't find any of the above to be a particular fault.

Here's a nice little detail, they've added a washer as a retainer for the float plunger:

All of the defects I mentioned earlier are shown in more detail in the following shots:

brass swarf in the banjo filter location, not a huge problem but make sure everything is very clean before use.

The main jet, probably damaged during installation at the "factory".

non-descript "dust" on the pilot jet's threads

I couldn't get the needle out, the retaining clip was getting stuck on this:

It looks like whatever tool was used, wasn't controlled very carefully and gouged out a pretty sizeable chunk. I had to use a file to carefully even it out.

Another deep scratch on the outside of the slide, which I also gently sanded down.

Finishing on the slide leaves a bit to be desired, but then again that's why these carburetters are so much cheaper than those made by Burlen.

All of this is fine... just not great. As we say around these parts "bene ma non benissimo".

As a closing thought let me ask you: what's original anymore, these days? All the names that gravitate around classic motoring have passed hands so many times, changed location, died and resurrected so many times... that at best what one can hope for is some original drawings and tooling to still be around. These Wassell carburetters are fine and I'll report back once I've had a chance to ride the Rising Star a bit and see how it does.

SIC ITVR AD ASTRA

Perhaps because they had caught on to the notion that life here began out there, BSA had a lot to do with stars.

Here are some of theirs that come to mind, in no particular order:

Gold Star
Fleetstar
Starfire
Silver Star
Empire Star
Star
Royal Star
Blue Star
Shooting Star

It seems odd to me that they would leave out such an obvious choice as "Rising Star", so when my chopper was built many years ago, I went for that name instead.

The Rising Star is named after the TSS (trans-stellar service) ship that reached Earth over 150,000 years ago.

I've had to wait too long and it's high time this bike came back out into the open; it has laid dormant with a broken oil tank mount since late August in 2017 (after putting it in storage, I had actually seriously pursued the idea of selling it, perhaps because I felt it was just not enjoyable), and it's time to take care of a few things that aren't quite right.

I should point out that some of the things I'm tackling now were already apparent in the very early days of the Rising Star, as I had mentioned here.

This is very similar to what happened with my Fastback, which went through a few iterations - all of them seemingly working and fairly final - before I was able to pinpoint those things that still needed a good bit of fettling to get right. The mistake there was thinking that just because it worked, that meant it was done, when in actual fact the difference became undeniable once I completed the Isolatic overhaul as well as the many other things I've done to it (the clutch, the top end, the tires, the handlebar...) but riding and becoming more and more in tune with the machine is so important, and one must always intervene to fix and improve, whenever the machine "asks" you to. Truly, this is important, with any machine that you feel is really worth something to you.

It would be silly to think that this is an easy bike to live with, it's not. This is a hard, tough and uncomfortable bike... and yet the handling quality as well as the fact that it is a one-of-a-kind custom bike mean that I keep coming back to it, wanting to ride it.

As you'll see in the coming months (hopefully in time for spring next year), this upgrade will consist in effecting some repairs (and improvements to avoid a repeat of the same problem) and addressing some "must fix" issues that I believe are the cause of this being not totally enjoyable.

I checked the tires first and foremost and was pleased to find them in excellent condition: there aren't any concerning signs of wear, distortion or deterioration (yes, you can see some surface cracks if you look closely, but bear in mind the image below is very zoomed in). These Japanese-made Dunlop are really good quality items:

Understandably, the battery was shot after having sit all this time (since 2018). I hooked it up to the Ctek charger and left it to do its work over a couple of weeks, the outcome was a clean bill of health so it can go back on the bike, at least for now.

And now we come to what may seem like an insignificant little detail, although of course you know by now that there is no such thing when it comes to these motorcycles. I had to remove and properly refit the kickstarter cotter pin. Oh that most loathsome, accursed, and confounded cotter pin.

Since the kickstarter will have to come off to get re-plated, this was the right time to fix the cotter pin that holds it in place. For such a small thing, this can be such a tedious thing to deal with.

There is no reason to use a cotter pin in general other than to make things "on the cheap". It would have been far better to opt for a beefy spline and a proper pinch-bolt (or even a Woodruff key and a locknut!) rather than a cotter pin, but this is what we have to deal with. When I look at BSA's unit construction motor, I can't help but consider this a rather utilitarian powerplant, built to a tight budget albeit with promising engineering choices. It performs really well and is generally trouble-free so, given a different path in history, this could have evolved into something very reliable, well built and very useable that could have easily lasted into the 80s and early 90s. You can actually see what one of these engines can truly be if you look at what SRM do to them, bringing them to a very high standard of reliability, functionality and performance.

Unfortunately, when I look at this goddamn cotter pin I can't help but think this is a quality flaw, one that could have been avoided. 

Once, many years ago,  I ended up mangling the cotter pin as I tried to get the engine to fire up (the bike had been left standing for too long, that time as well). I had to pound it out with a 5kg mallet and eventually, once I got it out, I held the chewed-up cotter pin in my hand, looked at it closely for a while and shook my head. "what a piece of crap" I thought. I replaced it with a new one that took a long time to arrive and that was supposedly made for the A50/A65 motor (it is admittedly beefy), but immediately noticed it didn't fit. I did end up using it for a short while, but knew I would have had to either find yet another one, or try to get this one to fit.

Removing the cotter pin this time was relatively quick and easy; we use the excellent ZEP 45 penetrating fluid here at the Monolith and it works wonders for this type of thing. Heat from the Stanley FatMax gun is also essential to avoid damage and get the job done quickly.

An inordinate amount of time was then spent filing away at the flat, refitting, checking, and repeating the process, and the result is finally a perfect fit (third photo down):

One way to do this is to line up the flat with the top of the vice using a magnet:

As an alternative, you can fix a file to your workbench and grind the cotter pin onto it. Whichever way you do it, it is imperative you control each motion, in a single direction, and that you do not "lift off" at any point, or you'll end up with an uneven, rounded-off mess.

Sadly, with the notable exception of Andover Norton, this is a very common occurrence when it comes to spare parts for classic British bikes: things are cheaply made out of crap materials with crap machinery and with not the slightest indication that whatever drunken idiot made it had any idea about proper fit and actual size. Nothing fits together, nothing lines up, there is no precision, no quality control whatsoever; every casting is porous, imperfect and full of burrs. There is no consistency among spare parts manufacturers (meaning the same part number can result in vastly differing items), nothing ever fits out of the box and that is unacceptable. I could understand this from a soviet or Chinese bike (and still not excuse it), but the "mystique" of the brand and a Union Jack sticker are just no longer enough to hide that these are almost just as bad.

There is no excuse for parts that don't fit together. It cannot be acceptable to say "it is commonly necessary to" file, grind, shape, forge, the part to fit. No more of this nonsense.

While the rational brain argued all this, the emotional side was happy to just look at the bike and revel in how cool it is:

Now, I realize I've just ranted on about how badly these motorcycles are made, but... here's something else that's undeniable: switching from the Sportster's high precision parts, castings and all the many sturdy details that bike has, to the BSA (it would have been the same on the Commando), I do appreciate a simpler technology that doesn't require much in the way of special tools, just a lot of patience and dedication. Simpler parts that are the bare minimum to get the job done (think of the control levers) and are nice and light, yes, there is value in that.

Before I even attempted to start the bike this time, I took off the float bowl and removed the jets assembly: predictably, everything was gunked up with old fuel, probably the blasted ethanol and whatever other crap they put in fuel these days. I was really surprised by the state of the main and needle jets in particular: these were fitted as brand new parts yet look trashed now. After all, this carburetter was rebuilt ten years ago but spent half of that time rotting away at the back of the shed. It follows that the result is five years of wear and another five of decay, meaning it's time to refurbish this once again. I have to admit it took a couple of rounds of cleaning (including an ultrasonic bath) before the engine would start: the culprit was a blocked pilot jet circuit - this is a very common occurrence with bikes that have been left standing for too long. There are many technical articles online that all brag and show off a wealth of knowledge and understanding of fluid dynamics, as well as blatantly plagiarize from one another, so I won't add to that, but the crucial thing to understand is how the pilot circuit works and why it is there to begin with. It's there to provide air/fuel mixture at closed throttle, all the way to about an eighth open, so it is essential for starting and initial pulling away. If the pilot jet or any part of the idle circuit, including the mixing chamber and the transfer ports above it, is blocked, the bike WILL NOT START. The mixing chamber is akin to one of those royal burial chambers in the Egyptian pyramids, you know the ones they find through some tiny tunnel that's a mile long... well, it's the same here, the chamber and its transfer ports are machined during the production stage and then sealed for all millennia with a welch plug, never to be seen again. You can surely appreciate how difficult those areas are to clean, especially because of how delicate and precisely calibrated they are: if you try to poke at them with wire, even really small gauge, you will likely ream ports and jets out of size, rendering the whole carburetter essentially useless. And if the inside of the mixing chamber is corroded, which you won't be able to see, in all likelihood the carburetter will never quite work properly. You need to get at the two tiny transfer ports before and after the slide to make sure they're free: that's where fuel for starting comes from, not from the jets.

The green arrow in the photo above is pointing to the pilot circuit air intake. The one on the right is shut with a welch plug after machining an identical tunnel, which is used to supply fuel to the pilot circuit.

If we flip the carburetter upside down we can follow the air flow (green) until it meets the fuel (in red, coming from the float bowl). Note location of the pilot jet, shown by the yellow rectangle. Air and fuel combine in the mixing chamber below that round welch plug, and feed the engine intake through two tiny transfer ports.

Above, you may or may not be able to see the pilot jet, this is with the air mixture screw removed and the only way to reach it (without drilling through from the other side, which I would not recommend).

I replaced the mounting flange O-ring as the one it had had clearly stretched out of shape. After that, I fitted a new float bowl gasket and got the bike to start, though it is running very rich, which probably means I buggered the pilot jet as I attempted to unblock it. I'll try to see if I can tune it, otherwise it may be time to replace this Amal. We shall see.

All of this nonsense was just to get the bike started, imagine the scope of what's coming!

TO THE STARS!

TO VICTORY!!

that little Triumph.

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...