It’s all about the chemistry…

but not the emotional type. The chemical type, as used to unblock the exhaust and restore the corroded petrol tank and on my Cyclemaster.

NOTE: THIS BLOG INVOLVES USING SOME VERY AGGRESSIVE CHEMICALS, SO PERSONAL PROTECTION EQUIPMENT SHOULD BE USED, FOR EXAMPLE, RUBBER GLOVES, GOGGLES, FACE MASK ETC.

READ THE INSTRUCTIONS ON THE CHEMICALS AND FOLLOW THEM. ALSO DOWNLOAD THE MATERIAL SAFETY DATA SHEET (MSDS) FOR EACH CHEMICAL AND COMPLY WITH IT – YOU HAVE BEEN WARNED!

First the blocked exhaust.

Apart from cutting the exhaust open, scrapping the carbon out and then welding it back up, there are two, frequently used, methods. The one I’m not prepared to try, involves pointing  an oxy-acetylene welding torch down the exhaust until the carbon is burning, then turning the acetylene off, so the oxygen feeds the burning carbon – a bit like a blast furnace. They say don’t worry about it glowing red and smoke bellowing out? And that it will self extinguish when the carbon has been burnt. But that sounds a risk to far, so it’s the second method for me.

Simply get some caustic soda (sodium hydroxide) from your local hardware store (Wilko in my case) and fill the exhaust with it.

NOTE: Caustic Soda is an aggressive chemical, so rubber gloves (marigolds) and eye protection must be used – as a minimum.

I mixed the caustic soda quite strong, with reasonably warm water (not boiling) and left my exhaust in an old plastic bucket overnight, with bungs in each end. The carbon softens and comes out a black gunge when you rinse it with the hosepipe. I did mine 3 times and the last time there was no gunge, just brown water.

Take extreme care, as the caustic soda reacts with aluminium and can stain chrome – not an issue on the CM. This method was quite simple and worked for me as the exhaust has a nice crisp “pop” now; a sure sign it’s free flowing.

Second, the rusty petrol tank.

My Cyclemaster tank had been stood for so many years, the petrol had crystallised at the top and turned to black rusty gunge at the bottom. I tried various cleaners that all helped a little but bits of rust were still getting into the carb. I hope to do some long distance rides and don’t  want to risk a breakdown due to blocked main jet, so the tank must be cleaned and treated.

This is what it looks like inside and it’s worse further back in the lower section.

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The method I’m using is to “treat” the inside of the tank with Phosphoric acid. It acts as a rust converter, not remover. The rust is iron oxide and the phosphoric acid converts it to ferric phosphate which is soluble in water so can be washed off – in theory, so let’s see if it works. The acid also etches the steel, leaving a grey surface appearance and increasing the rust resistance.

Remember, use personal protective equipment, as you are working with a strong acid.

My supply of Phosphoric acid came in the form of a ph adjuster used in horticulture, from ebay. It’s 81% concentrated and I bought a 250ml bottle, so that’s 200 ml of acid. The CM petrol tank is small at 2 1/2 pints which is approx 1.5 litres and I used all of the pH Down, so my mix ratio is 7.5:1.

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The fuel tap and integral filter were removed and the hole bunged with Gaffa tape as I’d read on the internet that this would work. It’s important to add the acid to water, rather than the other way round, then top the tank up to the brim.

I then placed the  Tank in an old plastic bucket and gave it shake every few minutes. It was during shaking that I noticed the garage floor fizzing, like an Alka Seltzer in water, as the Gaffa tape was coming off! SO DON’T USE GAFFA TAPE. Do the safe thing and find a bolt that fits the hole and screw it in securely. Fortunately, I had the hose pipe ready so I gave the floor a good wash down, including washing it Baking Soda to neutralize the acid.

After 20 to 30 minutes I removed the acid, gave it a rinse with the hose pipe for another 15 mins, then rinsed it with a baking soda solution. And this is the result:

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The next step is to thoroughly dry the tank and I used a heat gun to do this. When your are 100% sure it’s dry, give it a spray inside with WD40 or simlar.

Side by side, you can see the improvement is massive – job done, or not quite…

I say not quite, as unfortunately the acid has affected the outside of the tank.

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It just goes to prove, you shouldn’t believe everything you read on the internet, as I’d read that Phosphoric acid has no affect on paint – wrong! Perhaps I made the acid too strong? Or perhaps the original Polychromatic paint isn’t resistant to acid?

Anyway, I was unsure whether to paint the tank but that’s now been resolved for me.

So the next blog will be my experience on painting the tank and the other parts. Oh and adding those difficult red lines…

eat your heart out Mr Bluemels…

that’s Mr Bluemels of the world famous Bluemels Brothers Ltd. – manufacturer of automotive accessories and more importantly, number plates!

For most of the 20th century there was one motor accessory manufacturer whose name stood for top quality British Engineering and that company was Bluemel Bros Ltd.. Founded in 1860, at one time they manufactured a huge range of superb quality products including OEM steering wheels, auto lamps, cycle lamps and accessories for grand touring cars. They were one of the few regular suppliers to the bespoke coach builders of the 20’s & 30’s, catering to the likes of Rolls Royce & Bentley. As the coach built motor business shrank with the introduction of serious mass production in the 50’s, so Bluemel’s business evolved and by 1961, their portfolio included auto, bicycle, and motorcycle accessories, plastic moldings, dials, and number plates.

BLUEMELS-NUMBER-PLATES-original-1957

However, by 1983 the company faced insolvency. And like so many great British companies they folded. Worse still the name lives on in the guise of SKS Bluemel – a German bicycle mudguard manufacturer – how sad. And so typical of many other great British companies.

So, it’s down to me to make the rear number plate for my Cyclemaster. I doubt I can do it as well as the Bluemels Brothers but I’ll give it a try. The first thing I need is some material and I’ve “acquired” some 18 SWG mild steel sheet and some aluminium sheet. Applying the Colin Chapman principle, the ali would be better as it’s lighter and more suited to my puny engine and equally puny legs!. However, I’d prefer to weld the mounting brackets in place, rather than have unsightly bolt heads showing, so the steel it is; and I’ll just have to work on the legs.

So after cutting the required size, I scribe a line 5mm from the edge to form a “safety edge” (bent back, in other words). The line is positioned in the vice and the blank bent back using a rubber mallet to avoid denting the plate.

Each side is bent back to within 25mm of the corners. I then cut  a suitable radius on each corner with tin snips and formed each corner back, using an old socket.

I left a tab in the centre of the top edge for a rear light. Now, to keep the boys in blue happy, it should really have a clear area on the lens to illuminate the number plate and comply with the Road Traffic Acts. However, I’m a risk taker (and a cheapskate), so I’m just using the Raleigh rear light. My plead for leniency would go like this, “Being practical officer this autocycle doesn’t go any faster than a bicycle. So if you want to record my registration number, in the dark, just walk alongside (or jog if I’m going downhill) and ask me”.

Now I need mounting brackets; one at the bottom with a single bolt fixing i think and one slightly above the middle with two bolt fixing. Bottom bracket first. I cut a strip of steel then formed it into a U shape as shown below, using a suitable screwdriver as a former.

I then turned it over in the vice to close it up, then squeezed it back on itself.

After drilling and filing to smooth the edges and clean it up, the finished bracket looks like this. Ready for welding, once I’ve made the top bracket.

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Which is a bit more difficult, as I’d like it to follow the form of the mudguard. I started by bending a strip of steel around suitable formers by hand – my bike stand and a screwdriver in this case – see below.

However, my rear mudguard has a raised centre section so the bracket needs a relief groove to clear it. I formed this, using the vice (again) and a screwdriver (again) and a hammer .

and it turned out fairly well. Not perfect but the shape can be carefully improved by using (you’ve guessed) a hammer.

I just need to cut and bend back the tabs and it’s ready for welding onto the plate. To get the angle and length of the right, I used the well tried method of cutting a piece of cardboard as a template – easy to cut to get it right then use it to mark the metal.

Now welding is a bit like brick laying. You don’t need a degree in engineering, you just need years of practice and more practice. I wasn’t a bad oxy acetylene welder in my day but that was in the 70’s. And when I say “my day”, I mean ONE day! So, first thing is to set up the MIG in the “welding bay”.

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I’d love to say the weld below was my first attempt but it wasn’t. “Pigeon droppings” is an apt description of the test welds but it did come together eventually – unfortunately on the last one.

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And after priming and painting, this is the result.

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The last job is to fix the self adhesive alphanumerics and this can be difficult as you only get one chance. The method I used was to apply masking tape as a base line to get them level. I marked the tape with the position of each alphanumeric, leaving me with the task of making sure they were straight.

And now the final steps of drilling, fitting and standing back and admiring.

but the Bluemels Brothers would have nothing to worry about, had they survived.

and finally, some Bluemels adverts from Graces guide,

Im1951MShow-Blumels

Im19360610Cy-BB

Im19250306MCT-Blue

Im1920Cov-Bluemels1

and the last one is a gem.

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I particularly like the bit, “a junior member of staff (male or female) can handle the simple assembly procedure.” In other words, so simple a female can do it – sexism hadn’t yet been invented, just practiced!

And look at the name of the Sales Executive…..

 

More thoughts on the warm starting problem…and some science

After furiously pedalling my warm Cyclemaster to get it to start, I found it began to fire as I rolled the throttle to almost closed. So I’m trying to figure out why, as this could lead me to the solution.

Fuelling control on a 2 stroke normally works like this:

  • Pilot jet – controls idle to around 1/4 throttle
  • Slide cutaway – controls 1/8 to around 1/2 throttle
  • Needle and jet – control from 1/4 to 3/4 throttle
  • Main jet – controls from 1/2 to full throttle

Now the Amal 308 carb is a basic item as it doesn’t have a pilot jet and adjusting screw.  And without a pilot jet, fuelling for warm starting can only be controlled by the cutaway and needle jet. So the next step is to understand how the carburettor works and the answer is the “Venturi Effect”.

The Venturi Effect was discovered by an Italian physicist called Giovanni Battista Venturi and it goes like this:

The Venturi effect is the phenomenon that occurs when a fluid that is flowing through a pipe is forced through a narrow section, resulting in a pressure decrease and a velocity increase.

In a carburetor, the pressure decrease creates suction that causes fuel to be sucked into the passing air where it mixes and gets drawn into the engine. When starting a warm engine with a normal carburettor, the fuel would be drawn through the pilot jet and the pilot jet suction port is positioned just behind the front edge of the throttle slide (engine side). This is the narrowest part, so the point where the air is moving the fastest and the point of maximum suction – see diagram below.

slide-closed

However, the Amal 308 doesn’t have a pilot jet, so fuel can only get drawn from the Needle Jet and here, I think, lies the problem; it’s in the wrong position when trying to start a warm engine! The suction just isn’t enough to raise fuel up the Needle Jet Tube, at low air flow.

Also it gets worse if you open the throttle. This increases the area above the needle jet, so the air velocity decreases and the suction decreases to the point where no fuel is drawn into the air – hence it won’t start. If some fuel is drawn up, the engine doesn’t fire as it’s getting too much air and the mixture is too weak to fire, as the throttle slide is up.

slide-open

However, as you close the throttle, the air flow is restricted, the mixture gets richer and the engine fires.

I believe this may explain the poor warm starting many Cyclemasters suffer.

It also explains why tilting the carburettor to the left helps; it simply lets a little petrol run into the venturi. And you probably noticed in my “kick-start” video that the engine started on idle, i.e. throttle slide almost down to get down to get maximum suction at the needle jet and limited air.

So, to start your warm engine, I suggest:

  1. mark the idle position on the throttle control and set it just above this point,
  2. tilt the bike and engine to left for a few seconds (experiment with angle of tilt and time),
  3. kick-start or pedal the bike.

and hopefully, it’ll start – before you run out of breath!

Good luck, I hope this helps and please let me know your experience.

Addendum

For those of a scientific mind the Venturi Effect is governed by the Bernoulli principle. And Bernoulli’s principle is why aeroplanes and birds can fly, why a football follows a curved path when kicked with spin and why ships must maintain a minimum distance when they pass in opposite directions. I can explain if anyone wants to know?

a pearl of wisdom for starting a warm cyclemaster – or it may be baloney..

you decide.

This probably isn’t new to experienced Cyclemaster riders but I’m not one of them, so to me it’s a discovery. A discovery, from the need to stop pedalling up and down the road, to start my Cyclemaster “Sir Walter” and annoying the neighbours.

The first 15 mile ride has noticeably improved the engine, it even sounds crisper and it was definitely going better at the end. However, it does have a problem starting after standing for 10 to 15 minutes. Starting from cold – no problem. Starting straight after stopping – no problem. But after 10 minutes it just takes a lot of pedalling before it fires. My Cyclemaster friend, John, tells me he also has the same problem and I know from the internet that others do, so what’s the cause?

Well, I’m thinking the motor runs a fairly weak mixture as it gets 240 MPG and this makes it reluctant to start when it’s cooled a little. I’ve tried the choke but this just floods it as I can smell petrol when pedalling and it doesn’t have a float “tickler” to raise the fuel level and richen the mixture.

However, it seems to start really well “kick-started” as shown below

and I have an explanation and it goes like this.

When you kick-start the way I did, the bike and motor are tilted to the left. Now the float bowl is on the right of the carburetor and the petrol exists the float bowl on the left. So when you tilt left you raise the fuel level at the main jet and this richens the mixture – like “tickling” the carb.

fuel-level

This theory may be a load of gibberish or baloney (or rotvälska for my swedish followers) . Or it may be a pearl of wisdom. So I’d be interested in your views and whether it works for other Cyclemaster riders?

You could of course, pedal in a fast, tight circle to the left and this may work as well but I take no responsibility if you get dizzy and fall off!

almost a hen with teeth – unbelieveable but true

The amazing power of the internet (or the “herdy gerdy” as my mother calls it) has come good. That and my pig headed determination, has found the closest thing to hens teeth I’m likely ever to find – in Poland of all places.

I’ve found a manufacturer of hub parts that are pictorially very, very similar to the 1950’s Cyclemaster Eadie Coaster hub. My guess is they are based on the same design as the Cyclemaster hub that was originally made by BSA in Birmingham; a Polish manufacturer has just bought or “used” the design. But they only sell to Distributors and the nearest is in Slovakia!

However, I’m on a roll, as Miroslav of the Slovakian distributor is willing to send the parts I need. The only issue is whether I can be sure they will fit my Cyclemaster, based on photos only but it’s worth the risk as I can’t get the parts anywhere else.

It’s not identical, so I’ll need to make an extension piece but heh I’m an engineer – I can do anything (within reason and given time…and I’ve got plenty of that)

So it’s bank transfer and fingers crossed!

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