Story of the Royal Baby

predecessor of the RE125

The sound of Motorcycle

Royal Baby

1938 - 1950

1939 Royal Baby at Stokvis
A picture from a Dutch newspaper of 25th of April, 1939
1939 Royal Baby manual
Cover of the Dutch instruction
manual of R.S. Stokvis

The original design of this motorcycle was by DKW in 1935, a 98cc 2-stroke known as the DKW RT100. In early 1938, the Nazi-German government instructed DKW to cancel its relationship with its Dutch concessionaire, R.S. Stokvis en Zonen of Rotterdam, after the Dutch company refused to force out its Jewish owners. In the Netherlands this DKW RT100 was a very popular light-weight motorcycle due to lower tax rates for motorcycles less than 60kg. (see further below)

R.S. Stokvis searched for a factory that could manufacture and deliver large enough numbers of small light-weight motorcycles on a very short term. They came in contact with the Enfield Cycle Co. Ltd. and simply took an example of the DKW RT100 to Royal Enfield. Technicians of R.S. Stokvis who had a lot of experience tuning the 98cc DKW engine for racing purposes designed a larger engine of 125cc with so called Typhoon fuel flow system. Royal Enfield's chief designer, Ted Pardoe, was responsible for the faithful reproduction of the DKW RT

Joop van Heusden of R.S. Stokvis with management and engineers of the Enfield Cycle Co. Ltd., 1939
Royal Baby Joop van Heusden

Two prototype versions of the RE125 were displayed in Rotterdam in April 1939 under the name "Royal Baby". A Dutch newspaper article of the 25th of April 1939 discribed this event and the bike as follows:

During manufacturing, the experience gained by the Stokvis company with those small motorcycles was amply utilized. For example, whenever there had been difficulties with certain DKW parts they were redesigned and replaced. There has also been searched for improved materials for all parts, so that weight savings are achieved, so that the definite product of "the Royal Baby" weighs only 48.8kg. Fully equipped, a motorcycle must weigh less than 60kg, so that the Royal Baby, including petrol, oil, mirror, horn, pillion, remains below that weight limit. The material used for the Royal Baby meets the highest demands.

The engine is a two-stroke block engine of 124.8 cc cylinder content, bore and stroke 53.8 x 55 mm. A so-called Typhoon fuel flush has been applied, so that the engine keeps running 2-stroke perfectly, 4-stroking does not occur. Lubrication is achieved by oil mixing through the petrol. A flywheel magnet of completely new design has been used. The flywheel does not have to be disassembled for checking points or cleaning. A special muffler is fitted, which effectively dampens the sound. The Royal Baby has a completely welded tubular frame with pressed steel fork. The gearbox in a union with the motor crankcase has a drive gear on ball bearings, the other shafts on silent bronze bushes. There are three gears with manual gearshift, freewheel and kickstarter. Furthermore, the machine has internally expanding drum brakes and Dunlop balloon tires 2.50 x 19. Undoubtedly, the Royal Baby is an interesting machine with clever technical details and a neat appearance.

The first two machines arrived in Rotterdam on the 12th of April 1939, delivery starts the first week of May, 100 machines are promised and they hope to catch up on orders in June, after which they can be delivered from stock.

World War II interrupted plans for civilian production after only a few were made and only a few of the 10000 ordered, were delivered to the Netherlands and the rest was cancelled due to war production. That happened to be not bad for R.S. Stokvis company, because of the technical problems the prototypes had, especially the ignition and the piston, which were not constructed as van Heusden had designed. Because of this, the bikes had to be pushed into running most of the time and quickly overheated. The Enfield Co. Ltd. had not trust those foreigners with their progressive ideas, which actually were based upon years of experience with the DKW RT100. We see this model with little change as model WD/RE in the second world war. Even after the war ended, the starting problems were not solved and the RB was discontinued. In the Netherlands the Royal Baby was called the Royal Miscarriage. DKW started producing their much better RT125 in the western section of Germany in a much more modern factory than Enfield's at Redditch. If only Enfield had used the design of van Heusden...

The Royal Baby, origine of the Royal Enfield model RE

The story of its designer Joop van Heusden

J.G. van Heusden (translated from Dutch)

van Heusden's family website (only in Dutch)




Born: Sept. 1908
Died: 1 Nov. 1943

There are people who, from their earliest childhood, seem to have been born for a certain interest and whoever thinks that Joop van Heusden as a boy and later as Technical School student dreamed about motorcycles, is wrong. Joop only wanted one thing: to Sea! Sailing is what Joop wanted and nothing else, and it was a more regrettable disappointment for him that the accident with his bicycle, which left him a scar on his head, finally got him a rejection of his service in the Navy.

In this way, the young Joop van Heusden, when he was nineteen years old, was faced with the task of looking for a job in a completely different field than he had dreamed of. Two possibilities were open to him, a job at a pills factory and the position of warehouse worker serving with Mr. Augustine, in that time (1928) importer of Ariel. Joop chose the latter and made his entry into the motorcycle world.


Joop was a peculiar boy with an iron will and a deep sense of justice and whether it was a simple motorcyclist or his supreme Chief, Joop said exactly what he thought. He had no easy character and did not hide it, but on the other hand he was the first to see that and few could mock himself with such delight. The outsider might find him sometimes cumbersome and weird, those who knew him better knew that they could build houses on his friendship.

Van Heusden learned a lot from the fast growing business of Mr. Augustinus and that was not difficult for him, because he liked to learn and never stopped. Few had a technical library like him, and none of those few would certainly have made such a useful use of it. Joop could be asked any question at all and without fail, after a shorter or longer browsing, came up with a well-founded answer.

Van Heusden soon became the technical Ariel expert in the Netherlands and when the concession moved to Stokvis Ltd. in 1934, he followed and joined Stokvis. It will be thousands of motorcyclists, who got to know him as a technical expert and he was especially afraid of those who came to complain about the parts that they had broken themselves. No, Joop van Heusden could not be fooled.


When Stokvis Ltd. became the agent for DKW in 1934, Joop faced a difficult task. He saw a lot of potential in those little motorcycles, which were still far from perfect and which no one else believed in. Thanks to his sharp criticism, these were the first "less than 60s" quickly improved and to prove that they were good Joop started to participate in competing with these small bikes. Everyone laughed at him, because that was obviously madness, but that laughter soon turned into a great admiration when they discovered, which a sporty and technical performance could be delivered by a good craftsman with those small bikes. The DKW-RT team became a permanent fixture at all national and foreign competitions and what Joop has done for the popularization of the small engine is not to be underestimated.


In the meantime, van Heusden continued to study in all areas of engine technology with fury and when in 1938 Stokvis was stripped of the German makes, he could without hesitation take on the great task of designing a light engine himself that would be built at Royal Enfield: the Royal Baby.

Later, in the wartime when we all had little to do, he often came in the evening to our editors, sometimes with sharp - and usually justified - criticism of the contents of our magazine, but very often also with sober and witty stories about his difficulties in teaching stubborn Englishmen how we Dutch want our light-weight motorcycles.

With Hans de Beaufort, who was busy working on his book "Two-stroke motorcycles", Joop became very friendly and it would have been useful for many motorcycle manufacturers to hear the debates of both these two-stroke experts.

Changing times forced Joop into the gas generators, to which he had a real aversion and the dry humor with which he could tell how he kept cars, dredgers and other devices going, would make the recording of them fully worth it.

Joop was one of those people, who was always there for everyone, muttering and grumbling, and no one appealed to him in vain. Who knows motorcyclists, knows that they can ask many and strange questions and a lot of times our editors benefited from his almost inexhaustible knowledge to satisfy the inquiring readers.


When we came up with the plan in the war to keep the KNMV (Royal Dutch Motorcycle Association) members occupied by technical courses and more knowledge of their machines, Joop was immediately enthousiastic and very soon he led courses in many places, which became highlights of technical enjoyment. Joop was particularly fascinating and had a rare flair to explain difficult technical subjects in a crystal-clear way. Hundreds of KNMV's members will remember with gratitude those afternoons and evenings for which also professionals did not spare money to hear the sparkling spirit and the great knowledge, which was so dryly expressed there.

The data for his lectures van Heusden had carefully and neatly recorded and it is, as a matter of fact, unfortunate that these data have mysteriously disappeared after his death; they would have formed the basis of a new technical motorcycle book, which Joop had wanted to write and which now could have shaped such a wonderful memory of him. (*)

Joop was as persistent in his friendship as in his hatred. Peter, the dog, his books and his gramophone records were his best friends and, on the other hand, few will hate the Huns so wholeheartedly as he did. It will not surprise anyone, therefore, that Joop thoroughly performed a lot of illegal work as well; a fair, honest figure like he hated Jerries and especially traitors and his only great danger was that he did not hide it.


And yet Joop van Heusden would also end his working life by a German bullet. Riding back in his car from the Hilversum grass track races on 31 October 1943, a red light flashed in the dark, which - as it turned out - was intended as a stop sign; when Joop noticed this too late, one of the German heroes shot at the car and hit him in the neck. With his usual coolness Joop still gave some advice for dressing the wound, but the wound turned out to be too serious and on 1 November 1943 he passed away.

With Joop van Heusden, the Dutch motorcycle world lost a zealous, clever and decent guy, whose memory will remain in high honor with his many friends. Our editorial staff lost one of her best and most loyal employees.

( Nortier, MOTOR magazine, 32nd year, # 4, 31-08-1945, page 60.61)

(*) The notebook has been preserved and finally found "in the attic" at his widow's and is now in the possession of Edward van Heusden.

Joop participated in several competitions:


on "such a thing"

Field race experiences with a DKW-RT model 1935. pic07Motor01

It was in the spring of 1935. After finishing the traditional tour I arrived in Wageningen and almost the first thing I bumped into between the cozy crowds were three small motorbikes. Those things had a lot of attention, but at the time I just didn't think a lot of them. I thought they looked too much like pushbikes, even though it was noticeably much lower and I did not think that they would be useful. But when I spoke to the chief mechanic, he told me that they had just finished the tour with the three of them and that the journey had been fine!

The more I looked at it, the more I liked the thing, even if it was just to run errands. A test drive was soon put in order and under the attention of the visitors, I switched to the first gear: full of enthusiasm I let go of the cluth, but that went not well! The engine stalled and I had to start again. I had immediately learned the lesson that "such a thing" should be treated calmly, but when I gave a shot of gas, I learned a lesson again, but then in another way: what acceleration had such a thing!

I liked it and the little RT was as good as bought. I immediately spoke to Van der Made, the Utrecht dealer, and the purchase was done quickly. They would take the thing to Rotterdam to clean up and a week later the crate came to me. And let me say right away, that all my acquaintances went out of their minds to mock "that little thing", but I let them talk, I knew that the stuff would find its way, but that it should first be seen and tested. And the chance to demonstrate my little bike to a big motorcyclist came soon, because shortly afterwards I took a nice afternoon to running in the RT. On the way to De Bilt I was overtaken by Kees van der Voort, in those days a great trialist, who was riding a brand new Velocette, which he would ride in trials that summer. We went out in the direction of Amersfoort, he slightly slower and I rode a bit faster than before to the Leusderheide, where Van der Voort sometimes showed me, how to climb the steep sand slope opposite "Waterloo". He tore straight up, but I went directly after him and I never forget his surprised face when he stopped on top and looked back and discovered me right behind him. "How did you come here?" he asked stupefied, and of course I said: "On my motorcycle", but he barely believed it, I did.

But in any case I had once again become enthusiastic about the RT and we immediately agreed that I would come up with "that thing" in the coming trial of Tilburg.

Let me tell you right now that I had never raced a race before, let alone a trail. Of course I had been a spectator, but that was all, frankly, I was not very optimistic about what such a thing could do in the field: for such a low price you could not possibly expect a competition machine and in addition, my engine was not even properly run in. But even though I thought it was "a tiny thing", I wanted to experience the fun of racing once.

A week before the party, Van der Voort told me that three of those little things would ride along. His Velocette was not yet loose enough for competition, so he had one of those touring engines available, to try his strength on RT too, a Stokvis mechanic would ride the third machine.

Timely in advance the three miniature racing motorcycles arrived in Utrecht, where I loaded them on my trailer and took them to Brabant. That trip was a test in itself because every moment we had to stop to tie one of the three or all more firmly, but in any case we arrived in Tilburg. I still remember how Jan Moejes laughed at us in Culemborg, because we wanted to ride a real trial with three of those "little rags".

And in Tilburg we came again in the center of good-natured spectators, when we found the Stokvis mechanics who unloaded the machines of the trailer with serious faces. To the public's great amusement the RTs came out: equipped as "real" racemotors, without headlights or other unnecessary accessories and they grinned at the prospect that soon such a big man would put himself in its saddle and race it. When we went to sign-up, we gave for the sake of certainty that we would be only in the 250cc class, that's it. We had our engines put secretly behind a shed at the start, so that there were only a few who had seen them, but the faces of the organizers were worth gold, when the three of us rode the starting line! We doubted if they would let us start, but after all we payed our registration fee and we were wise enough to choose a place in the back, so everything could go without any objections: there was nothing to be done, even though everyone was of the opinion that none of us would see the finish line again!

We did stand out though because I had removed the silencer from my machine and tied the loose pipe to the frame. A great noise that the little thing made!

Anyway, the moment of the start for the 500 cc class had arrived and my heart was pounding in my throat. Should I just do that in the same way, swirling between the others, only to be gone first? No, I'd better not start with that, because I did not quite understand that side of competitive riding. Finally our starting time had come, the 350 and 250 cc classes together. The audience was close to us and I was afraid that there would be a joker who would hold my rear mudguard, but fortunately that did not happen.

The flag went up and I could just see how Van der Voort secretly crawled a few places forward and pushed slightly to the right outside. I did not immediately understand what that was necessary for, but I did exactly the same. After all, he had already experienced many more trials and it would have a reason. I came to see that I was suddenly standing next to such a big, real rider on a much larger motorcycle. I thought: "I let him start first, then I will tail him neatly and then I will follow him". I did not know who it was, because I did not know any of the participants. Later I heard that he was one of the very good riders, and that he had become second. Then I thought how beautiful it would have been if I could have stayed behind him, because then I would have become third ...... But my "less than sixty" could never keep up with him.

The start flag dropped, the whole crowd shoved and roared past each other, and suddenly I understood Van der Voort's reason to crawl forward when I saw him passing a few riders through the outside.

As I mentioned earlier, this was my first race and I had taken the "real" off-roaders as an example: leather pants, leather vest, large motorcycle boots and a beautiful helmet as a high hat on my head, but then I started to get angry: it was a sizzling day, in the middle of summer, and the sun had burned all over the moor all afternoon, so I began to feel I would melt, so I was tightly packed, and to the extent of disaster my helmet moved back and forth over my head, and I kept swishing up and down my saddle whenever I bumped through one of the many holes, but luckily my bike stayed down and I up, although I often thought, that "that thing" would go ahead without me. But we were still riding and that was quite a thing. Van der Voort had seen me shoot off at the start, so he had to drive somewhere in the front, but the third RT had not yet showed up, so he would ride somewhere behind me. It went pretty well and so I did my best to catch up with Van der Voort.


Then I suddenly hear a great noise behind me and immediately something like a bullet shoots past me. I was so shocked that I immediately ended up in the sand! I noticed that it was one of the 500 cc class that were already working on a series of laps. In any case, I was now warned and so knew what it meant when I heard such a noise behind me again. And I also understood that the great brothers would almost be home when I had spun my fifteen rounds, but that left me quite indifferent, especially since at some point I saw Van der Voort disappear in a forest, where he should not be at all. Later I heard that at that moment the right-hand half of his handlebar had moved away from the left-hand half, so that it was difficult to continue. For a moment I felt great that I had the lead of the three little ones.

After a few more rounds, I got a hefty thirst and thought to myself that they should give me something to drink, just like I had seen in cycling races, but that did not work out well. The next round it had become so bad, that when I passed the jury-tent, I yelled that I was thirsty and that they had to prepare drinks for me. I did not want to lose too much time, because I knew that there was another RT behind me and I wanted to leave it behind me. The next round I came out of the forest, and at exactly the edge was a lady with two small children they had a piece of orange in their hand and wanted to give it to me. Yes, I would have liked that, but they were standing behind a tree and just on a section, where there is a nicely paved path. So I turned the throttle and hoped that they would be in a better place the next round. At the jury tent, however, someone gave me a bottle in my hands. Well, that was my luck! I grabbed the thing, and while I was driving I wanted to drink, but most of it went over my vest and shot at my neck, so that I got a shower as well. Anyway, I had some of it and deposited the bottle with a sweep in the heath. It just comes to my mind that I still have to pay for the bottle

The more laps I rode, the more motorcycles I saw along the side and at the finish. I wondered if they had already been finished or that they had failed. I saw a few of the 250 cc class between them and understood that they were in any case broken down. Not sporty to watch competitors with such a lot of fun, but I was still a bit uncomfortable and thought: "The more they break down, the better my chance will be!"

Along the whole circuit the spectators were shouting at me and waving at me, until finally I myself did not know what was going on. Also at the finish they were dancing and jumping and pointing out that I had to go even faster, but "that thing" did not want to go any faster (because in those days the engines were not fiddled with as nowadays). And let me not pretend I was alright, I had more than enough of it! I was glad that the man with the flag gave me the signal at last, that I could stop.

The audience was extremely enthusiastic and I was glad that everyone had now seen that such a small motorcycle could still perform. There were also direct buyers with me, who wanted to buy it of me and others asked me where they could get "such a thing". Fortunately I saw a DKW dealer and to get rid of all the attention, I sent him the whole bunch of buyers to be. I was ready to rest a bit!

If I remember correctly, I became seventh of the 17 competitors and a few days later I received an automatic cigarette case as a consolation prize for my first race on "such a thing" J.V.H.

(MOTOR magazine, 30st volume, # 4, 23-01-1942, pages 53-55)

April 1937, the 5th KNMV Spring Reunion Rally in the Netherlands; Captain van Heusden as leader of the DKW-RT brand team of Stokvis. They traveled a total of 600 km to demonstrate the reliability and the ability to prove man and machine.

pic09HarzTeam-L pic10HarzWinter pic11JoopBeker01 pic12Harz01-L

24 Apr 1937, the 5th Harz Run in Germany;The Two Day Rally in Germany starting from Groningen; total 500 km. Via Ter Apel, Braunschweig, Bad Harzburg (overnight), Bad Grund, Lautenbach, Seesen, Lippe Detmond, Oldenzaal. Extremely bad weather conditions. The DKW-RT brand team, led by Joop, won the first prize in its class; 678 penalty points and only surviving team!!

May 1937 in the 18th Dumonceau Cup Tour in Belgium/Luxembourg; A two-day trip from Antwerp via Ghent, Godverdegem, Ath, Mons, Waulsort, Beauraing, Esch sur Sûre, Luxembourg (overnight), 6 rounds on a racetrack, Sûredal, Clervaux, Spa, Côte de Malchamps, Mont Theux and Huy back to Antwerp. This ride was mainly meant for the classification for the International Six Days. DKW-RT team leader Joop finished 6th (overall) with 158 penalty points.

pic13Joop6Days pic14Joop6Days pic17Joop6Days pic15Joop6Days pic16Joop6Days pic18Joop6Days

July 1937 in the International Six Days Trial at Llandrindod Wells, Wales; A six-day trial with many international riders and (factory) teams; in those days to compare with a world cup / championship. Joop was the team leader of the DKW-RT team. The team won the first prize and Joop won the bronze medal.


April 1938, the 6th Harz Run in Germany;


Something about the

HOW and

WHY of the


by Joh. G. van Heusden Jr.

Now that the Royal Baby has appeared, we thought we could not do better than to ask the spiritual father to tell us something about his product. We were pleased to find Mr. Van Heusden , the technical expert of R.S. Stokvis & Zonen, prepared to do so, and thus one finds below his interesting account, from which he has completely omitted himself out of modesty. Editor.


Only purebred motorcyclists who are so accustomed to having at least about twenty-five brake horse power in a clearly audible tone sing the highest song and finding it a special kind of pleasure to use the foot switch and front brake to connect the endless string of bendy and straighter roads like a long straight piece of motorrider's ribbon flashing under them, only they will be able to imagine the storm of misunderstandings, which must undoubtedly have stormed me, when I saw December 1934 for the first time in a railway wagon a shipment of 45 motorcycles with a cylinder capacity of a 100cc.

The renowned ministry order of February 1935 made these machines as "less than sixty" a powerful tool to motorize the Dutch cyclists and at the same time myself - at that time even a little forced! - a propagandist.

It is not surprising that I, like so many, were seized by the possibilities of these small machines, that soon the propagandist turned from a sense of duty into an enthusiast, purely out of appreciation.

The product we had traded at the time, had as was to be expected, a very long way to go would it get to some degree the title perfect, and it is to be expected that one is at risk to consider the product part of your own spiritual good, all the more when you can find in it so many things very well known.


Above the rear hub, which clearly
distinguishes the individual spoke edge,
the watertight seal and the reinforcing rib.

And I can assure you that in our Technical Service not only the enthusiasm can be called a common phenomenon, but also the feelings to know: here is something of ourselves too! The road to perfection was also a long and often a very difficult one. The often quoted great possibilities, as they are sometimes called at large factories, have proved to be extremely insurmountable difficulties.

Once there was a real threat that the model in question would be taken out of production for lack of interest, but when the "export" article will be taken up again as a tempting item, then this is a splendid opportunity to comply with the wishes and desires of the important export customer.

And soon, enlarged cooling fins, improved clutch and gearchange and great care in finishing them will have a favorable influence on the sale figures and will therefore automatically apply to our enthusiasm. This same enthusiasm, which made it possible that instead of a normal factory machine, it was always "our" machine and in which, in our thoughts, an ideal light-weight machine was thus given shape.

No wonder, that when less than six months ago it was necessary to look for another manufacturer, we wanted the product to remain as popular as the one now. After all, this was our most achievable ideal in this area.

Suppose that it was possible, as one thinks so often: "I wish I was twenty again, but knew what I know now"!

Well, six months ago it looked a lot like us, that we were twenty again, with all the facts, for which we had so much sacrificed.

We were twenty again - did we know what we know now - and our ideal? Our light-weight machine? Well, the Royal Baby is almost identical with the thought of our ideal, a most ideal light-weight motorcycle. And knowing what a care and attention was spend both in construction and in the choice of applied materials, I can personally assure you that our new Royal Baby is closer to this ideal than any other creation in this area.

It was a very rewarding task to convince the gentlemen manufacturers of the Royal-Enfield factory that it was not to be assumed that a bicycle was to be the basis in design, but rather the motorcycle as the starting point for this small light-weight motorcycle.

The main characteristics as a motorcycle and therefore a motorcycle-frame with a real steering head, consisting of a forged steel lug in one piece and with closed-in head bearings instead of open cups, motorcycle brakes, really waterproof and rear brake as being the most used by laymen, even provided with reinformcements, motorcycle wheels with spokes with strenghtened heads, strong rims and real balloon tyres. The frequently occurring problem of spoke breakage was canceled by punching the spoke holes in the rims in the right direction, while the steerability was very well served by the use of the Dunlop 19 x 2.50 tires, which tyre size has a real motorcycle profile! Logically, the rubber belt suspension that we created was also adopted and the handlebars were fitted with thin, easy-to-grip handles.


The heart! Right crankshaft, connecting rod and flywheel.
On the left is the piston, on which one can
clearly distinguish the "sunken deflector"
with the gas-guide back in the middle.

And now the power source itself.

Although the application of a two-stroke engine seems to be in flagrant contradiction with my personal conviction, which recognizes the superiority of the four-stroke engine, this is not the case on closer inspection. It can be said on the one hand that in the case of a four-stroke engine there is the valve mechanism consisting of several parts, then again it can be argued against this that this indeed has "its purposes"! Anyone who is capable of putting the power sources of two-stroke engines and four-stroke engines of equal cylinder contents next to each other will have to see the correctness of our position. And those who know more about the performance figures of these two types of machines will not need any further arguments to agree with this, to say nothing of all kinds of very strange carburation phenomena and therefore failures in the combustion process!

Nevertheless, you can't deny, that for very small cylinder content (and eventually 125 cc can be called very small!) the mass that rotates and goes up and down like a valve mechanism becomes a somewhat extravagant luxury equipment, looking at the profit on effective horsepower.

However, mainly the imperative requirement of simplicity-before-anything was reason enough to proceed with the application of the two-stroke engine, while for the same reasons there was also a possibility of using mixed lubrication. On the one hand, the necessary "fiddling" with petrol-cans and oilmills in the present modern time, which requires speed for everything, can hardly become more patience, with the light machines with its unprecedented low consumption figures the periods of "refueling" so far apart that this undoubtedly seriously felt inconvenient can not be called insurmountable!

And it is at this power source now where the Royal Enfield engineers have been able to let out all their abilities and know-how. And credits them certainly for their sense of reality that, in the construction of the whole, they have taken serious account of the experiences which our company had gained with the sale of more than 15,000 copies of the engine type concerned.

In order to obtain the most ideal combustion space, one had to try to use the surfaces of the piston - to obtain the most ideal combustion, one had to adhere to the old-fashioned 'deflector' - piston - what was more logical then a combination of these two?

What could be the disadvantage of applying all current flushing systems with flat pistons, regardless of the number of overflow ductules used and the name that they have given the flushing system?

The cylinder!
In the picture below one clearly sees in the middle
the inlet port to the crankcase and next to it the
two ports to the cylinder, through which the gases
from both sides flow into the piston floor.


The shape of one of the inlet channels can be
clearly distinguished on the adjacent photo.


The most critical moment for a two-stroke engine with flat piston is that, where the exhaust gases are just at the point of outflow and the fresh gases at the point of overflowing. After all, at that moment inevitably the hot old gases and the various gases come into contact with each other, which contact is caused by a special position of the overflow channels or by trying to minimize the number of special overflow channels.

The essential cause of the non-intimate connection of these gas streams is, however, a completely different one and to the full understanding of this we will have to stray for a moment in the gray theory.


Our fuel then, as being the most used: petrol, is chemically a hydrocarbon compound. During the combustion thereof, or again chemically: oxidation, not only hydrogen arises, but the released hydrogen joins the oxygen and thus forms water. As proof of this, just look at the end of the exhaust pipe of an automobile, where the engine is started in a cold state. The steam-plume then showing itself is steam and not oil smoke, the free-flowing drops are water and not petrol, as they sometimes mistakenly assume. Good: the hydrogen is released when the gases are burned. Well: a well pre-compressed, mixed mixture has, when ignition is used, about a temperature of 14000 C while this temperature will increase to about 16000 C at the end of combustion. During the exhaust stroke, that is to say when the piston is going downwards, a significant cooling occurs due to contact with the increasingly larger cylinder surface, as a result of which the departing exhaust gases still have a temperature of about 6,000 C. It is with these exhaust gases that the fresh gases come into contact, during which touch a certain edge combustion occurs. During this subordinate combustion process, the already mentioned hydrogen is released and thus forms an automatic separation between hot and fresh gases. Now, however, this separation is directly dependent on the setting of the ignition timing and the strength of the gas mixture used. And these are precisely such important points, that by doing so, most of the so-called "inexplicable" phenomena occur in the case of two-stroke engines with flat pistons.

An advance of the ignition timing did not ever have any advantage in the case of a two-stroke engine, so this is automatically left intact. Due to wear and tear at the breaker points, however, the timing can be retarded and with this a subsequent incineration of the fresh gases. This in turn results in the exhaust gases obtaining a higher temperature than that provided for by the manufacturer, which in turn causes the hydrogen "fencing" to collapse, and the result is the further premature burning of various gases, indicated by back-spraying in the carburetor! The same consequence is the reduction of the carburetor jet, which results in more real consumption figures. In the case of two-stroke engines it is often done by setting the ratio between fuel and air more poorly and thus also getting higher combustion temperatures with again the same effects. That this is not a "well thought out" theory, which you can easily determine yourself, if you have a two-stroke engine with flat piston, carrying out the above mentioned experiments yourself! The "deflector" piston lacks these phenomena totally and therefore on this point alone such a piston could offer certain advantages.

During the long-term experiments, which we carried out with existing 98cc engines, in order to obtain the same number of horsepower as from 125cc engines and thus be able to make a somewhat more bearable figure in the race classes, we have not only learned that this was virtually impossible, but moreover we learned a lot about the behavior of the various gases when changing carburation, position of ducts and piston profile.

With honors I must mention here the ever sober, but in truth not to be missed, part of the head of our workshop, Mr. de Vries, and his co-workers, whose cooperation for solving countless difficulties always turned out to be a much appreciated support!

It is thanks to these observations that we found the remarkable influence of the use of overflow channels which are wider at the bottom than at the top. Thus applied, the overflowing gases, rather than as a storm, will flow more like a "typhoon" into the combustion chamber in our system, a fact that our system got the name of "typhoon flow"! So in short: using a semi-deflector on the piston results in being less dependent on the setting of the ignition timing and carburettor adjustment; applying upwardly narrowing overflow canals a better filling and thus more effective horsepower is realised, which can can be of good use for light-weight motorcycles, flat roads and windings! Not to mention riding with a passenger and lower consumption figures.

Besides the gas: the ignition!

The biggest enemy of all flywheel magnets, in which an induction coil must necessarily be used, is: heat. As a result of the induction on this spool, an accumulation of heat in the iron core thereof arises, as a result of the mounting of the anchor plate against the crankcase wall, an increase in the temperature of the insulated material also occurs. The result is two forces acting against each other, namely insulating material, which will become tighter and therefore less elastic, and the iron core, which will force the enveloping layers through expansion. The result will be that the windings are pushed together and the final result is again a coil with a short circuit! Furthermore, necessary repair and control work with the flywheel mounted over the anchor did not actually increase accessibility.


Our first assignment was therefore to improve accessibility and if possible: to lower the temperature for the anchor. By mounting the flywheel on the crankshaft, as it were inverted in a housing cast on the crankcase, not only all of this was made possible, but also a short flywheel shaft was obtained, which does increase the service life of the ball bearings on this side a great deal! The crankcase housing was closed by a lid, which carried the required coils on the inside and a separate casing on the outside under an easily removable dust cover. The end of the crankshaft was provided with a small cam on a tapered end for the breaker unit, thereby reducing the movement of the breaker hammer and thereby reducing the risk of breakage. In addition to adjusting the breaker cam and breaker hammer, the flywheel housing cover was also mounted in slotted holes, so that the coil could be adjusted relative to the flywheel in order to obtain the best spark in the strongest magnetic field. Let me close this almost "hymn" to the ignition by stating that by a sixfold division of the flywheel magnet the capacity for the light could very easily be increased to 18 watts and if necessary to even higher


After all this there is the choice of primary transmission. If one was completely free, both in the choice of a factory and in the choice of materials and not hindered by a certain price limit, then undoubtedly the gearwheel transmission would have been chosen as the best trans mission, since it could certainly have been made without a noise. However, the production costs available for this not only light-weight, but also in terms of price, "economic" vehicle, does not permit the use of a noiseless and therefore costly gear transmission, so that with the less costly, but in any case always retractable roller chain transmission in oil bath chain case the same results could be achieved. In cooperation with the three-speed gearbox, of which also during gearing the gears always stay in pairs in engagement, thus a significant amount of care was spent on the noiselessness.

The same care will be found in the beaded edge of the gas tank, which will prevent damaging of cables; the sealing of all bearings and pivot points, so that grease leakages will be excluded and countless other details.

That I personally can not be anything other than being enthusiastic about our Royal Baby, one could each take in his own way, but I wonder:

Would you think otherwise, if you, like me, had been in the unique opportunity to witness the emergence of a motorcycle in no more than six months from scratch, and even to assist where necessary and possible? You would unquestionably show me the same gratitude to those who would have made this possible to us and worked with the same enthusiasm on the product!

MOTOR magazine, 27 th volume, # 16, 21-04-1939, pp. 429-433

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A New Year's pondering of Mr. Van Heusden, who is fully endorsed by the "Motor" magazine's Editor!


Well, that was behind us! The New Year's visit of relatives and neighborhood acquaintances has been fullfilled and it is suddenly strange quiet at home. The house which was strange with all that visit - just as if it were not your own house at all.

For a moment I stop looking at the strangeness, now suddenly all the crowds are gone and left nothing else than used cups and glasses and cigars on full ashtrays. And then there was the memory of a conversation, which was difficult to bring to a different subject, than that about points and coupons and then again about coupons and points. My dog ​​was involved in the conversation - "it will be difficult having another mouth to feed!" I looked casually at the last additions in my book collection - yes, That will also soon be over if there is a lack of paper! "

It became a difficult conversation with a difficult visit. The ladies told each other, "that they were happy even to have something" and the fear was in their eyes, just from the thought what else could happen! And the gentlemen praised the little cigars and praised the fact that they had happily a good cigars-dealer!

No ... it had been a strange afternoon and only one of the neighbors had at the end of the visit - just in the door-opening - said something justs: "Well, we are still there thank God and that's worth it!"

For a moment I have to think about that last remark, now that I let myself down into my lazy reading chair - "We're all here!" Where else had I read that?

We are all still there and fortunately the burning fireplace is still there. The farewell at the door was cold and satisfied, I put my hands to the warming fire. It is certainly the conversation of this afternoon, which makes me think faintly, "how long-with-the-coal", but I force myself in another direction: After all, we are all still here!

Tomorrow it will be Monday at the office and that's nice - just a short week. On Mondays it is always very cold there and it will take until noon, before all the heating is well and thoroughly pulled through. "You see - the supervisor once said to me - that's the easiest thing if you have to work with your whole body, then you will not notice cold that easily!" And while I think of the cold of the day of tomorrow, I need to that statement of the past, "as-you-must-work-with-your-body!" And because of this sudden thinking about the supervisor with his workshop and his mechanics, now I also know where I had read that before, that last statement from my neighbor: "We are all thankful for it all!"

And suddenly it is back in my mind as I felt it when I read:

They are still there!

Indeed, they are still there, just as self-evident, as we have always expected them, where we have always managed to find the much-needed at all times of the day and sometimes also at night: "They are still there, our garage owners and our motorcycle dealers! "

Crazy, that a person has not thought about that before! "They are still there!" And so much we were confiscated by the joy of our own, "we are all still here!", That we suddenly forgot how we used to be, in days, which are now forever seem to lie behind us, so often willing to shout, happily, "a lucky thing!" when they had whispered to us, "your garage owner-your repairer-your rescuers of need-they are still here!"

It is hard to confess myself, but in fact I am a bit ashamed. It is true that it does not even seem possible to be only one day of the year-even the very first! - to do that what you had planned to do on the last day of the previous year. And the last day of the previous year-that was only last night.

And when I suddenly think of my supply of coal, which I have to deal with very economically - and when I suddenly think of that workman's statement, which shows that if you have to work with your whole body, you are not so high in need of heating; Well, then my decision is made. After all, they are still there!

In the corridor I shoot in my faithful leather coat and call in that I am back again.

I suddenly knew what to do: I go to that neighbor, whom I converted to a motorcyclist at the time. And that I'm going to convert him now again, that's what's with me! When I come to him a little later to inquire whether he still has the motorbike of his, then he says shyly yes, but soon he becomes curious when I ask about the well-being of "the thing", For a moment I see the reflection of the foolishness in his brain that "that neighbor" came to ask after his motorbike on New Year's Day as if after a sick housemate, but I feel so strong as a seasoned missionary and it does not take long for him to know where I want to go.

But then come his objections and his reservations. "How could I think of running a motorcycle on the road today?" And if I pretend not to understand him, I hear him mutter something about "claiming" and "surrendering", in short a repetition of all that fright, that all car owners and motorcyclists already had in their heads during the mobilization of the Dutch army, and his face shivers a fear, as if on every corner of the streets a "representative" of the Wehrmacht is in charge of claiming vehicles that have been forgotten. But that also takes a while, because I really do not need much time and effort to tell him that thanks to our perfect system of personnel taxes, they know where and where not vehicles can be found. And it is on the basis of his own description that the tax authorities can tell whether the vehicle in question is still usable or not.

And for the sake of completeness, there is still his report of the tyres and then neighbor can do nothing else but - albeit with a sigh - see the sober reality as it is, strict and well informed, so that careful covering under an old one curtain in the guest room or a trip on the street with the motorcycle and any claims that may come from this can not be considered a difference. And by the way - I tell him to know from a good source that claiming is now slowly coming to an end, and then with his conscience his enthusiasm returns.

And truly: the student, the convert will surpass his master. He says with enthusiasm that they should know this position in the Club. Indeed, he says, we must also remember that it is not right going to put things away, nor for our properties, but also for them. "If we had needed them in the past, then they were there and they are still there now!"

Not much later, with a little excitement, he walks around the block with me for a little while - the same block that we had so often walked as "air-guards". And his enthusiasm can not be turned off, the whole club has to know, all his friends and important people. He will advise "the boys" - that's what he always called his colleague-mechanics! - to rent a hand cart and then they can come and get the machine from him. And in the meantime he will take care of other and a lot more addresses. His plans already cover a whole campaign, which I am trying to slow down in vain.

When they have rented the hand-cart, then he will take care of a few nameplates, and if his machine is put out of the house on the cart, then he certainly will get the assist of his friend the press-photographer.

Do you think they would print such a photograph in the newspapers? You see, if they see something like that in the paper, then more people will wake up their conscience and that will never hurt - after all, they are still there! He almost shouted the latter over the whole square, and I do not doubt whether the many pairs of eyes behind the different curtains did suspect an imminent neighborhood quarrel and remain in glorious anticipation of such an unexpected event. We are now almost around the block and walk past my garage. "Do you still have the car there?" He asks with interest, pointing his thumb over the shoulder to the door, I feel like a school boy, caught by the master at licking liquorice! "Oh, yes" is my weak defense, "it is on blocks and so can not leave!" The rather positive spoken word "so" seems to catch my neighbor for a moment and the window watchers expects "that-now-it will-start". But by putting his arm around my shoulder in delight, my neighbor puts all this hope into the ground.

"Do you know what you should do?"

And before I have time to tell him that I do not have the slightest idea, he says: "I would make sure that the boys get a hand car and you let the people from your garage come with the tricyclepcarrier full with tools!". And then we start to tell each other what we will have to do and what we will not have to do. "Look" I propose, "to pull the bike apart sounds nonsense to me. Let them first scrape the carbon off and let all the oil out of the sump, if there is still some in it. And the oil tank and the petrol tank, because that can easily get sticky and eroded. And then the tyres from the wheels, because the rims are rusting before you know it!" His tip was also not crazy. "Let them put some mothballs between the upholstery of the car, when they think they are finished already, because a mechanic is not a housewife!"

Inwardly very satisfied, I sit myself down at the table a bit later. Splendid, what a good plan. That does a man feel good. Especially when you know that it will not stay with just an intention. "They are still are!" It does not bother me anymore, that I do not know where I read that again. "We are there too - and they will notice that, that's what it's all about!"

How was Adema van Scheltema's song again last night about New Year's Eve?

Every year we find ourselves better .... then when the year started!

And it is this New Year's contemplation, which I also wanted to bring to your attention - in your line of thought!


MOTOR magazine, 29 th year, # 1, 3-1-1941, pages 4 & 5




There are few people in the country who have experienced the good and especially the bad of the "Less than sixty" very nearby and from the first day off as Mr. John van Heusden, who first opened the section "less then sixty" in our magazine, later followed by "Dumigro". We are therefore very pleased to give Mr. Van Heusden the last word about this illustrious group of light-weight engines. His argument contains many points, which riders as well as manufacturers can take to heart.

(The headcliché is from the archives of the Stokvis Co., the second photo of "Motor" magazine, the drawing of Mr. Van Heusden).

When the "125 cc-issue" of "Motor" magazine made me realise even more than than before that the child has grown up, my thoughts went back to the autumn of 1934 and I see myself standing there again in the dark railway-wagon, which contained the first shipment of "light-weight" motorcycles. The nickname "boneshakers" for these vehicles was clear enough and did not require any further explanation: how would we ever sell that lot"? Only on personnel tax alone one one had to pay more per year in some cities than the whole motorcycle would be worth after a few seasons. Is it any wonder that the first thing I thought was to turn this whole first mission around and send it straight back to the factory?

But then came a new legal regulation: motorcycles less than 60kg would be free of Personnel Tax and look there on the headset the weight of our light machines is indicated as 49kg.

From that moment on the journey of triumph of the "less than sixty" began slowly but surely, a triumph that has now found "the growing up" of a real 125cc motorbike.

Now my own experiences are as it were tied to the name RT and my companions of other brands of machines forgive me, that I personally see the progress of the light-weight motorbike in the Netherlands as the progress of this smallest DKW. I can very well imagine that they each wish to see this progress embodied in their machines and they certainly have at least as much effort and dedication to this task. However, the unknown large numbers, with which the little RT machines appeared on the Dutch roads during that period, did however look like the progression only affected these machines.

In those days there was a lot of work on the RTlet and they needed it too. The numbers with which they were sold encouraged even greater effort and the results have certainly rewarded all this effort to some extent. And that was the reason for the wave of enthusiasm, which involved the proposed propaganda for the motorization of cycling riding Netherlands. No means was left untouched to prove the usefulness of light-weight motorcycles in general, and no opportunity was left unused to increase the quality and properties of the whole ever higher and higher.

The finish had to be decorated and preserved: simply put, but it meant that all had to be durable rustproof and three layers of lacquer before it went into the enamel stove.

Even "luxury" models with separate striping and lots of chromed parts had to be added, and that it was so difficult to achieve, a layman can hardly imagine what is a nice finish for a tank? What color and what kind of striping? There were whole parades of different versions of tank designs and the result of such a "plebiscite" was surprising, but right. The technical qualities of the whole had to be improved: gearwheels were widened, pin shift turned to dog-shift, magnetized iron became magnetic steel, varnished coils changed to impregnated coils in vacuum tanks. Profiles of rims were changed, spoke thicknesses had to be changed: it was a continuous coming and going of the many important but often useless indications of the thousands and thousands of users of these so renowned machines.

I remember two of the many "sessions" of the technical factory management, of which I can tell you what it was about: one, where the suspicion was expressed, that the smallest machine might disappeare from the program because of expected limiting production (note!). The restricted production was averted and the little bike became the official machine for the Hitler Jugend in Germany. And then the one in which we proposed to change the spiral springs of the fork, to such as used by the racing machines with rubber belt suspension. It was adopted, a crowning glory for the Dutch competition! Rubber belt suspension! On standard machines! The politeness forbade the esteemed technical college to declare the only "commercially" appointed Director to be crazy, but by being very tenacious the permission was given to use all this tomfoolery for the Netherlands and leave the risk entirely at the expense of the orderers. however, thousands and thousands of machines with rubber belt suspension, have proved the correctness of this "pig-headedness".

I was talking about the fact that no opportunity was left unused to show the possibilities with light-weight machines, but what this single sentence involved in work and what this demanded of the dedication and labor power of my closest technical helpers is truly not to describe in one article.

The first appearance of the light-weight motorcycle in the racing world caused a scorn of laughter and a compassionate shrug of the old pros. This has passed very quickly and it did not take long before the teams from the "less than 60s" had conquered their own permanent place in the results of the various motorcycle competitions. Unprecedented results were already achieved on "less than 60s" runs in the Harz, Dumonceau Cup Tours, Six Days Trials, etc.


The educating material these competitions have yielded is unbelievable. It is safe to assume that, for example, what has been done in a Six-Days trail with a machine weighing less than 60kg, would never be required by the greatest brute in daily life. Was it a miracle that of all the motorcycles of all classes they were gradually getting the least amount of misfortune? It should be remembered that every year 3000 to 5000 copies of the known brand were despatched and the statistics have made sufficiently clear the total increase over all brands at the time.

When you have lived four years, as it were, with a type of machine and you have experienced and promoted the progress of the thing step by step, then something grows on you which you would like to call your own. You always see changes and differences and you know exactly why this was done and when!

When I think back again of my dreams of yore, yes, then I know for sure that the arrival of these light-weight motorcycles for a lot of young (and undoubtedly also older!) Dutchmen meant a starting point and a basis for their dreams and fantasies. The stream of various letters, every day on my desk, were all written in such an enthousisatic spirit, that the completion of journeys, such as the Africa trip of our friend Gerlach and the East Indies expedition of Van Straten and his companion, were in fact no revelation to me. They were simply the embodiment of that which I myself have always seen as possible: the future is on the light-weight motorcycle!

Due to surprising events, I was suddenly, already a few years ago, given the opportunity to convert many of my future wishes for the light-weight motorcycle into reality, and it was only logical that I went further, after the sudden delay. What could Hans de Beaufort have made of it as an "ideal" motorcycle! Unfortunately I had to do with less idealism and pour some realistic water to my idealistic wine, but as a series of experiences with the "less than sixty" I would not have wished to miss this period anyway. One will know in the shortest possible time that you can write about ideals better than actually realise them, Hans! But to the point.

"Less than sixty" is going to disappear and at the same time I will - under that title at least - surely with a big sigh of satisfaction of motorcycling Netherlands, vanish from the screen. And you wanted on the occasion of this goodbye to ask another question, dear reader? You would be allowed in advance! And you would like to know, of course, what my modest opinion may be about the future of the "light-weight motorcycle"?

The fact that the weight limit of these machines, with a view to a certain type of tax, has lapsed, is a measure that I can only welcome warmly. Although I must say that for a factory where one can indeed control the manufactuering of a complete motorcycle in all parts, it was not impossible to create an entirely usable motorcycle within this limit. For the many Dutch brands, including very good ones, it was, being mostly 'assembly-companies', dependent on the import of various foreign parts, a bit more difficult. And then the requirements for the these machines were such that the weight limit was approached very closely and was in fact repeatedly exceeded by the user. And the absence of effective control of this weight limit made the whole legal regulation a miserable display of which one was inconvenienced and the other not.
Yet I am of the opinion that there is a real thread for the future. Let me first say that I excepted the possibility of abandoning already in November 1939 when I draw a sketch of the light-weight motorcycle, with no weight limit taken into account. The outbreak of the war between the largest industrial countries of Europe has made the appearance of this machine beyond the drawingboard impossible, but I write about it to show my objections to the decision now made that there is a real danger for the future. Let me first say that the abandon of the weight limit was previously thought possible by me and in November 1939 I drew a sketch of the light-weight motorcycle, with no weight limit taken into account.

In my opinion it is possible, yes, even necessary, not to bring the weight of such machines above 70kg!

After all, what is the great danger? Far too much has already been listened in my opinion to the desires of that group of young motorcyclists, who have switched from their former non-tax-free motorcycles to the "less than sixties" and requiered things as foot gearchange, race-saddle, speedometer and the like. Also the required top speed is unnecessary for and I give all manufacturers of these machines the assurance that the big group of cyclists, of tram-, train and bus passengers as utter laymen don't care much about those at all.

Give them a reliable machine, strong enough for Holland's headwinds, with wide mudguards for our muddy rainy roads and with sufficiently thick tires for the too bad cobble stones. Make it strong enough for pillion riding (because they do!) And ensure as little maintenance as possible (because they don't do that anyway!).

A battery is nice, but they will neglect it, a dynamo with brushes is even more beautiful, but they do not understand it and the appointed "craftsmen" even much less! And if you have to make a single part available at a reasonable price because it does sometimes brake, better leave it out, because they pay nothing, nada and buy cheaper imitations, and then ten to one, that, if possible, the manufacturer has to pay for the failure of that imitation.

I know: it is a terrible picture that I paint here, but unfortunately the reality is not so far away.

The new 125-cc machines must, in my opinion, keep the good, but light, tires that have been manufactured especially for them, sturdy but light rims and no overly large brakes. Heaven is keeping us from getting overly large tanks and only foot gearchange!! (as a starter you still need both legs for balancing for a long time!) and please do not use spring frames or sidecars! And let me not even mentione built-in counters and other meters in life-size headlights, because my advice will be read as very strange, not to mention other words.

But this is to me no objection to express my firm belief, that the expiry of the weight limit could sometimes mean hopeless minors on the commercial side for some manufacturers. And this is what those gentlemen have in their own hands, I think!

I'm leaving now. And like "less than 60s" forever. Whether I will be able to emerge again under one or another alias? I think 'my colleague, Dumigro, in a very praiseworthy way, has taken over my task and would not like to withhold you his prose. I do not know what is yet going to happen - by the way, who dares to do a very small prognosis in the area of ​​the motorcycle future?

I have fullfilled - my family and relationships think me utterly crazy - with a "less than sixty" several seemingly impossible tasks to the best possible end, but to give such a very small prognose, you know, I wouldn't dare to do that right now!


As early as August 1939, exactly two years ago, the following 125 cc "Royal Baby", designed by Mr. van Heusden, was already in the pipeline, weighing about 60kg, speaking about a visionary forsight ......

MOTOR magazine, 29 th volume, # 32, 08-08-1941, p. 559 - 561

(*) - The drawing is dated 2-11-1939!

In addition to the articles given here, Joop was also the author of the section "Less than sixty" in "Motor" magazine in 1935 and from 1941 to 1942 he was editorial employee of "Motor" magazine, official publication of the K.N.M.V. (Royal Dutch Motorcycle Association)

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