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The Devil Rides Out

by Mark Daniels

Clark Scamp

Drawn by a light in the sky, we continue to follow the road south.  Dusk beckons, and with it, again will come the devils that have tormented us on our journey.  We hurry on as the sun sinks behind the woods of the New Forest, exploding the autumn sky into a vivid paintbox of gilt.  Towering high above the trees and silhouetted against the embers of fading sunset, Judge Peterson’s slender gothic needle at Sway points ominously to the heavens of advancing night.  Demonic yellow eyes start to glow in the darkest patches of old dead stumps, as we run down the jetty at Lymington to jump at the last second, onto the departing ferry.  The tolling of a church bell drifts across the water as land looms from the mist, while our cloaked pilot in the prow raises an arm, and points a bony finger—our destination, The Island of Vectis!

Pick up any motor cycle encyclopaedia you like, and strangely, hardly anyone seems even to acknowledge the existence of this maker or its machine!  The Scamp was the rather unlikely product of ship’s mast manufacturers A N Clark (Engineers) Ltd from the even more unlikely location of Binstead, on the Isle of Wight!  It’s quite baffling how a maritime company decides to get involved in moped manufacture, but the Scamp project was started in 1967 as a departure from the usual yachting business.  With no previous experience in the field, that really is some wild diversification!  Still, all credit to Clark; they bravely committed themselves with an imaginative and unique motor of their own design and manufacture, mounted in an adaptation of the CWS ‘Commuter’ bicycle.

Clark Scamp

Glass’s Index lists:

‘Scamp’ 49.9cc (2-stroke) 38mm bore × 44mm stroke, introduced March 1968 from engine no. E10001, frame no. U10327.  Scamp moped introduced.  Single speed, auto. clutch, rigid frame, brakes front 3½" hub, rear calliper type, tyres 12"×2", ½ gal. tank, direct lighting.

There is absolutely no ‘stock’ reference material available for the Scamp, the only source on this machine coming from original literature, club archives and records of enthusiasts’ contacts with the manufacturer, so we really have to make the most from this information, and study of surviving examples.

Our test feature machine today is engine number E11850, frame number V12063, still in original condition and finished in red with gold pinstripe.  This bike is the highest frame serial so far recorded by the register, and by contrast, also for the photoshoot, the second blue bike displays engine no. 11955X, and the lowest recorded frame serial: V10316.

Mounted on the left-hand side of the rear wheel, the conventional piston-ported engine features radial finning on its alloy head and cast iron cylinder.  The crankshaft is most unusually constructed in that the flywheels bolt together by socket cap screws, through the big-end bearing core, with the con-rod seeming to run on uncaged roller bearings, so the whole assembly would appear home serviceable with no more than a simple Allen key!  A Dansi flywheel magneto hangs off the nearside journal, while the drive outputs to a simple single-stage centrifugal clutch.

Clark Scamp

The rear ‘disc’ wheel is a primitive assembly comprising of a Dunlop 12"×2" rim crudely bolted and riveted through the spoke holes to a pressed steel disc form fixed to a driving flange.  It may be little surprise to find such wheels often display some buckle effects.  The flange rotates on bearings around the rear axle, driven on a shaft from a large reduction gear running in an oil-bath alloy case, and powered by a pinion shaft from the clutch drum.  Turning a ‘power key’ located in the clutch housing enables the drive to turn the motor by a counterbalanced nylon pawl engaged through a slot in the clutch drum.  Once the motor is started, centrifugal force overcomes a spring to disengage the pawl.  The automatic clutch operates as motor revs are further increased.  Switching back the ‘power key’ disables the pawl as the clutch rotates into contact, returning to bicycle function.

The feature bike’s motor is fed from an original fitment 12mm Amal 369/162 carburettor, though the rider’s manual clearly illustrates a Dell’orto, so probably both types could be fitted.  The exhaust comprises two steel bowls bolted together to form a chamber, and is easily stripped for de-carbonising.

With its 12" wheels and 16"×2" tyres, the CWS ‘Commuter’ cycle borrows much of its general impression from the RSW16 bicycle and Raleigh Wisp, which pre-date the Clark by a couple of years.  Adaptations to the bicycle feature a hub front brake (though a calliper set is retained for the rear), Radaelli saddle, specially wide rear rack mounting the triangular petrol tank in its crook, fitment of a basic lighting set, and suitable control equipment.  The cycle propstand is woefully inadequate for the bike as a moped, and any attempt to precariously balance the machine on this flimsy leg is merely inviting the inevitable.  You might as well save time & trouble, and simply throw the bike down on its engine side every time you park!  Leaning against walls or even backing the pedal against a kerbstone is far less hazardous.

Clark Scamp

The lattice cycle chassis looks pretty impressive in its design and structural construction, being the nearest interpretation imaginable of a small-wheel version ‘Mixte’ frame, but anyone who’s ever ridden the notoriously twitchy Raleigh Wisp is going to approach a Scamp with some trepidation.  It has much the same geometry as the Wisp, but with the engine mounted at the rear wheel, the centre of gravity is going to be further back—oh dear!  Still, one has to remain optimistic!

Engage drive mode by pulling down the ‘power key’ and latch into position by rotating it 90°.  In drive mode, the Scamp can be reversed easily on the freewheel, but moving forward will now turn the engine, so needs the decompressor engaged to enable navigation.  Pull on the petrol tap at the fuel tank, and the choke is—a strangler on the back of the carb down by the rear wheel!  No linkage control, no throttle latch; you can just bet this going to be awkward!  We pedal up the road on the decompressor, drop the lever, and the drive disengages so we coast to stop with the drive pawl clicking.  The pawl doesn’t latch again until the bike stops moving, to allow another starting attempt—with the same result.  During starting, it seems the pawl instantly disengages whenever the engine stutters, and the trick is getting it to catch and run as soon as the motor fires.  This could take some time!

There is a primitive sort of tickle device on the carb, which comprises the top of the float needle sticking through a hole in the float chamber top.  You can press this to flood the chamber, though it doesn’t seem to offer any discernible advantage in the starting procedure, and a veritable disadvantage would appear to be as a direct access point to allow rainwater into the float chamber!

Clark Scamp
Clark Scamp

It takes several attempts before the engine does continue running, but then you’ve got to stop and dismount to open the choke shutter!  To stop it stalling (since we don’t want to go through the starting palaver again), the tendency is to keep it on the throttle, but the automatic clutch drags and the bike tries to make off down the road—so you have to hold on the front brake now, while you try and open the strangler with your left hand down by the rear axle!  This proves hopeless if you’ve made the mistake of dismounting to the left side, possible but awkward if you dismount to the right.  Once the choke shutter is actually open, it’s just as well to lift by the rack to get the back wheel off the ground and rev it a bit on the throttle to clear its throat.  Now the engine starts to run slower without dying out, we can remount and get underway.

A lot of these starting difficulties would certainly have frustrated most customers, and it’s baffling as to why they ever sold machines fitted with the Amal carb?  The Dell’orto with its latch choke mechanism would have been so much more suitable.

Anyway, back on the bike and off we go, open the throttle, and the single-stage automatic clutch locks on in one bite at quite low revs, so the Scamp really just chugs off the line.  If you want acceleration, then it’s going to have to come from your own leg power!  As we start to build towards cruising speed, one also starts to become aware of the handling characteristics.  Take a hand off the bars to signal, and the Scamp feels as if it’s poised for any opportunity to go chasing rabbits in the bushes!  Just a little more edgy than a Wisp, but the Ariel 3 is still number one on the top 20 chart of ‘Bikes that are trying to kill you!’

Once the motor gets warmed up, Scamp cruises happily up to 25mph, above which vibrations start coming in through the Radaelli seat and the ride becomes uncomfortable.  Hot engine, on the flat, with light tail wind, our pace bike briefly glimpsed a very best of 30mph.  Downhill, 34mph maximum—and that really wasn’t going to go any faster!  Speed falls away readily as the bike encounters any incline, but it still manages to labour slowly up moderate hills at low revs without the need to pedal, as the motor digs-in once it falls below 20mph.

Both brakes prove suitably retarding when required, with even the rear calliper function proving surprisingly effective, though small wheel machines would typically be expected to deliver better hub braking performance anyway, advantaged by the basic law of physics.

The flywheel magneto is a Dansi set, and the Clark rider’s manual specifies lights of 15W front & 3W rear, but put in these wattage bulbs and the dimness is unimaginable.  More practical illumination is found by reducing the ratings down to only 3W for both front and rear, so perhaps the generator coil might be somewhat down on output?

Clark Scamp poster

Scamp’s motor ran smoothly and evenly throughout the trial with never any hint of four-stroking, a confidence inspiring little engine that, once you’ve got it going, feels as if it’ll run as long and far as you like.  Getting started however is a most deterring operation, and would obviously have proved unsuitable to many customers for practical everyday transport.  To make this situation even worse, the plastic drive pawl developed a further reputation for rapid failure!  Clutch function also appears to engage prematurely and makes slow running and acceleration operations un-conducive, while in the longer term, all the working components of the clutch are cast from zinc and very prone to complete disintegration.  The rigid frame and forks, in combination with the small wheels and vibration effects, quickly prove fatiguing; then add these factors to the sedate performance and spooky handling, and you’ve got a machine that the rider probably isn’t going to enjoy for long.

Tragically, the Scamp never found time to evolve, since it came and went in the same year!  Glass’s Index lists the bike as discontinued in November 1968.  It was reported from Clark’s that they ‘…could not compete with the Japanese and Continental companies already established in the market.  Due to continuing financial difficulties a Receiver/Manager was appointed by Lloyds Bank resulting in a 50% staff reduction at Binstead and a complete disposal of almost all finished machines and components…’

Clearly a catastrophic conclusion, but why the situation occurred isn’t really explained.  With a selling price pitched at 46gns, the Scamp was appreciably cheaper than its most obvious market competitor, the Raleigh Wisp at 57gnss, which was selling very well.  On the face of it, prospects for the Scamp might have looked pretty good, but the ‘continuing financial difficulties’ element could suggest that the company trading position might have been struggling for some while.  Reading between the lines that yachting work was failing to support the company around this time, the Scamp project was embarked upon as an alternative business generator.  Though March might have looked an ideal time to launch the bike to catch the start of the sales season, Clarks seemed unaware of motor cycle marketing practice of showing machines the previous November at Earls Court to ‘prime the trade’ and initiate the advertising for advance orders.  Trying to find period magazine road tests or articles on the Scamp is practically impossible, and Clark’s very own poster even fails to show a picture of the bike!

What seems to have happened was that Clark found themselves still sitting on a whole load of complete machines, cycles, engines and parts at the end of the summer as a lack of advertising had failed to generate sales.  The season had passed, and a struggling company was stuck with all the stock value—a classic formula for cash-flow foreclosure.  Big banks don’t tend to have much patience with small companies trading in the red.  Everything was flogged off any way it could go, even chassis without engines were fitted with standard cycle wheels at the back and simply cleared as bicycles.  Out on the streets, these could be readily spotted from the standard CWS Commuter, by the dedicated Clark rear carrier with its big hole where the petrol tank was intended to fit.

With a variation of the name, a new business rose from the ashes and still trades today in Binstead on the Isle of Wight as Clark Masts Teksam Ltd, and Clark Masts (Technical Services) Ltd. spare parts company—but don’t expect them to supply any parts for your moped, that’s all long gone.

No official figures are known of how many Scamps were actually made, but the company suggested 3,000–4,000.  With the frame series seemingly starting from 10000, and considering our test machine is the highest frame serial so far recorded by the club, a statistical projection suggests the total is more likely to be within 2,500.  How many survive today?  Who knows?  However, it’s certainly a lot more than some of the ridiculously low numbers being claimed in most of the adverts by people trying to sell them!

Some say that God rides a Harley, well that may be a little controversial—but if ‘Old Nick’ were to claim his own machine, who knows?  It might just be the Clark Scamp…

Clark Scamp

Next—The brief window of opportunity opens, to test another rare autocycle as it passes between private collections.  Such fleeting chances come Out of the Blue, and there’s no time to think—just grab the camera, notebook & pen, and go!  The dials of our time machine spin backward again, to another adventure.  A shattered Europe stumbles back to its feet, and it is the old machines that will have to rebuild the new world.  The most economic motorised transport is particularly in demand, and sharp commercial eyes spy an opportunity as Autocycles are emerging for their second generation.

Clark logo
This article was produced with the
assistance of
Clark Masts Teksam Ltd

This article appeared in the July 2007 Iceni CAM Magazine.
[Text & photographs © 2007 M Daniels.  Montage © 2007 A Pattle]

This will probably remain the most definitive reference article on the Clark Scamp—so in making this little piece of history, we believe in doing the best we can with the resources we have on the day, since it’s pretty unlikely we’ll get the opportunity to visit it again—or so we thought.  However, one of the benefits of publishing on the Web is the feedback we get and, in the case of The Devil, one such e-mail has shed new light on the demise of the Clark Scamp.  So this is not the end of the story, the Devil will be riding out again later.

Speak of the Devil…

Dear Mark,

I was the first owner of Clark Scamp KJE 90G, which I bought for £35 in 1968 from Allin’s cycle & autocycle dealer on Bridge Street in Cambridge.  I drove it home only to find that the front number plate readd KJE 90G, so back to the shop for new transfers.

In those days you needed L-plates, but no crash helmet. Insurance was 30 shillings per year (yes £1.50).

What a vile little machine!  The cylinder head wobbled around, making a lot of vibration.  The engine connected to the bike frame with a flat plate link.  This fractured due to the vibration. The rear light kept blowing due to vibration, so I hung the rear number plate on leather straps.  The centrifugal clutch wore out so I riveted on leather ‘clutch plates’ instead.  The advertised 200mpg was more like 20mpg when you opened the throttle.  I used to go to Marshall’s Garage on Jesus Lane for petrol and a shot of Redex.  Sediment always collected in the neoprene fuel line.

I went back to Allin’s for a chat and they told me to chuck the Scamp into the river.  So much for after-sales service.  Wonder how many more Scamps are at the bottom of the Cam?

I never used the Power Key.  It was only used if you wanted to push the bike any distance by hand.

Method of starting the engine:

Tickle the Amal carburettor

Shut the carburettor intake disk

Open the decompresser using the handlebar lever

Stand to the left of the bike

Left hand on the throttle

Lift the rear wheel off the ground using the rear carrier

Press down on the bike pedal to turn the engine over

When the engine fired close the decompresser

Open the carb air intake disk

In 1969 I rode the Scamp from Cambridge to Peterborough, to catch a train up North.  The spark plug fouled up on the way to Peterborough, so plug spanner in operation.  Up North I got a rear tyre puncture.  Not possible to remove rear wheel, so puncture repaired with bike lying on its side.

I then passed my driving test in Cambridge in a Ford Anglia 105E, so off came the Scamp L-plates.  I last used the Scamp in the early 1970s then gave it away.  Just out of curiosity I Googled Clark Scamp and saw my old bike on your website.

All the best from
Peter Dockerty.

[The old log book for KJE 90G lists just Peter Dockerty as the first owner and Anthony Silvey next.  The change of ownership was never stamped and the bike wasn’t taxed after August 1971, so it looks as if Mr Silvey never got it to work well enough to use.—Andrew]

This letter appeared in the April 2012 Iceni CAM Magazine.

Making The Devil

So what was it like producing The Devil Rides Out?  Difficult all the way is the best answer.  Taking several years in research and generation, source material was the biggest problem, since so little was available, and it was very hard to turn up much more than scraps of anything new, so it mainly came down to collation, careful analysis of what there was, and statistical projection.  Once we’d finally got the bike to work, the road test went well, and the main text on this one came together fairly quickly—but the original ‘maritime’ intro never felt right and didn’t let the story flow from the previous link.  So in the end, it got ripped right out, binned, and completely reworked.  The ‘demon journey’ was the final result, travelling south and crossing the Solent to the Isle of Wight.  Vectis was of course, the old Roman name for the island, and it all started tumbling into place like some antique Hammer horror.

The ‘little devil’ photoshoot had long been planned to match with this article, way back years ago, when the project to produce the feature first started.  I guess the idea was inspired by the original advertising poster.  Scamp’s tiny wheels and low engine, coupled with falling sun angle of early evening, meant practically all pics had to be taken at low angle to avoid shadows—but not until Rachael got kitted up, and framed in the viewfinder for the first shot, with the sunlight flashing off that red leotard; only then you know it really is going to work!  With the shadows lengthening, the shoot had to go quickly, with fast changes of set and location to follow the light.  Two rolls of film clicked through in 45 minutes, away in the post to the developers on Monday 18th June, and a fast closing deadline for Iceni2 at the end of the week.  The film and discs came back on Saturday 23rd, then straight on to Andrew for digital additions.  With the gothic arch and flames dropped into the lead picture, final lay-up of the magazine could progress, and then there’s all the printing to do!  The timing certainly ran a bit tight on this one, and it sure was a scramble to get everything completed for Peninsularis, but we made it—just!

The Devil Rides Out hit a final bill of £92 to complete the article, (film/developing/CDs £29, costume and props £30, fuel £33), so you can see exactly where the money goes, and all donations go directly towards production.

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Devil’s Epitaph

by Mark Daniels

Clark Scamp grave

2008 sees 40 years since the introduction of the Clark Scamp, and the anniversary of our presentation on the machine.

Fretton’s of Coventry advert

While our previous article ‘The Devil Rides Out’ covers the Scamp in feature, following its publication last year further researches have turned up fresh material and revelations have bubbled to the surface as a result of our readers’ responses.

I’m Backing Britain badge

It seems that Clark was adopting its own original methods to market the Scamp, employing sales rep, R T Townson, to travel the country, making personal calls on motor cycle dealers to establish agencies and secure orders.  At this time, in the mid to late ’60s, there was an on-going government-initiated programme to promote British goods and manufacturing—anyone remember the ‘I’m backing Britain’ campaign?  There are references by Townson that Clark had also been following this theme to promote the Scamp.

Glass’s Index listed the Clark Scamp from March 1968.

Managing Director of Fretton’s of Coventry, and Chairman of the National Association of Cycle & Motor Traders Committee, Reginald Reed, produced a moped sales presentation to the Blackpool Council meeting of 21st March 1968, and previewing the forthcoming motor show at Belle Vue, Manchester on 3rd April.  This report included an outline of the introduction of the Clark Scamp moped produced by Alec Clark from Binstead, Isle of Wight, as an entirely new machine to be listed for £48–6s–0d (46 Guineas), and being price-pitched as ‘the cheapest machine of the year’.  He went on to somewhat generously describe ‘The performance is lively [we wouldn’t!], maintenance remarkably easy, though the ride is rather noisy and a little rough—but remember the price—and it should find a ready market’.  Then closing with the statement that, ‘It may not be on view at Manchester, however’.

We came upon some interesting factory publicity pictures, showing two early Scamps, both with Isle of Wight KDL series registrations that reasonably date them to late 1967.  The people in the photo are, most likely, members of Staff at Clark: we have identified the man as David Bennett, Clark’s Sales Director.  The picture was probably taken quite close to the factory although the area is now covered with houses.  A close-up picture is further interesting in that it shows the engine fitted with a large Dell’orto carb, certainly the only one we have actually seen.  Although a few production machines had the Dell’orto carb, the majority appeared with the Amal 369/162.

Clark Scamp publicity photo Clark Scamp close-up

IceniCAM reader Paul Sugden relates that the Scamp moped was the subject of a ‘Breach of Confidence’ case raised in 1968 by a Mr Coco against A N Clark Engineering, for manufacturing the moped engine from his drawings.

In 1965 Mr Coco began market research into the possibility of producing a new moped, and proceeded to design one.  By March 1967 a batch of pistons had been made for him in Italy and sent to him in England.  In April 1967 there was the first contact between Mr Coco and A N Clark about the proposed moped and the company expressed interest in making it.  In a letter dated 24 April 1967 the company asked Coco to bring the prototype that he had built to the works of the company.  Over the next three months there were many discussions between the parties and Coco supplied Clark with information and drawings towards the production of what had come to be known as ‘the Coco moped’.  Clark did work on Mr Coco’s ideas and also put forward draft documents concerning the financial arrangements between them, but these documents were never signed and terms were never agreed.

On 20 July 1967, A N Clark told Mr Coco that the transmission of the Coco moped was creating a serious problem of excessive wear to the rear tyre and that the company had decided to abandon it and make its own moped to a different design.  The Coco moped used a roller-drive to the rear wheel.  When the Scamp appeared on the market, although it used a completely different transmission, the engine was substantially similar to Mr Coco’s design.

Mr Coco sued for breach of confidence in disclosure of his drawings.

There was a preliminary hearing where Mr Coco applied for an injunction to stop production of the Scamp as ‘interlocutory relief’.  The injunction was refused.  Clarks undertook to pay a royalty of 5/- (25p) for every Scamp engine manufactured into a special joint bank account on trusts.  The full trial would then decide how much, if any, of the accumulated money would be awarded to Mr Coco.

However, the trial never took place, the Scamp was discontinued, and Clark went into administration.

Glass’s Index entry confirms production of the Scamp as ceased in November 1968.

Despite not going to trial, the Coco v A N Clark case established quite a legal landmark, and is still widely quoted in legal cases as a test case example for breach of confidence.

It would certainly be of interest to add a reference copy of the original Coco drawings to IceniCAM Information Service files, if anyone might be able to turn up a print?

This epitaph could finally lay Scamp’s listless soul to rest, yet still may not be the last word on this haunting spirit.  Even as this passage is typed, an ongoing engineering project could mean that the little devil may return to grace these pages again someday—in some rather unexpected form!

Further information

Clark documents in the On-line Library:

Coco v Clark CH full text

Coco v Clark CH short text

Scamp accessories leaflet

Scamp adverts Trader 1967-12

Scamp adverts Trader 1968

Scamp article Trader 1968-02-23

Scamp article Trader 1968

Scamp clutch service sheet

Scamp instructions

Scamp leaflet

Scamp news Trader 1967-10-27

Scamp news Trader 1967-11-24

Scamp news Trader 1968-01-05

Scamp news Trader 1968-02-02

Scamp news Trader 1968-02-16

Scamp news Trader 1968-03-01

Scamp news Trader 1968-03-15

Scamp news Trader 1968-04-12

Scamp news Trader 1968-06-07

Scamp news Trader 1968-06-31

Scamp parts list

Scamp parts list update

Scamp parts price list

Scamp poster

Scamp Trader supplement

This article first appeared in the July 2008 Iceni CAM Magazine and was later updated with more information on the Coco moped.
[Text © 2008, 2011 M Daniels & A Pattle.  Gravestone picture © 2008 A Pattle.  Period pictures from IceniCAM Information Service]

Who was Mr Coco?

Information about the Mr Coco who suggested a moped design to Clark is not easy to find … who was he? 

On 25 November 1948, The Motor Cycle reported the arrival in Britain of three Italians who had ridden all the way on Mini-Motors which, in the picture below, look as if they’re mounted on very un-Italian Hercules bicycles.  Their arrival was planned to co-incide with that year’s Earls Court Motor Cycle Show and thus to pubicise the launch of the Mini-Motor in Britain.

1948: Three talian Mini-Motor riders arrive in London

The three riders were: Vincenti Piatti (designer of the Mini-Motor), Mario Coco (described as a technical illustrator), and C Garbardi-Brocchi (a journalist).  Is this the same Mr Coco?

More Devilry

IceniCAM readers may be aware of the motor cycle drawings by Nick Ward that regularly feature in Classic Bike Guide.  Co-incidentally, Nick’s drawing in the June 2008 edition of CBG featured a Clark Scamp.  Not just any Clark Scamp either, the model for the drawing was the blue Scamp that was featured in our The Devil Rides Out article.

Clark Scamp drawing by Nick Ward
© 2008 N Ward, all rights reserved

We are grateful to Nick for supplying us with a copy of his original drawing and for granting us permission to reproduce it on this website.

The Devil’s Disciples

Some of the people involved with the Clark Scamp

Alec Clark
‘The Man Behind the Scamp’: founder of the company, Alec Clark.

John Wright & Vic Vine
In the publicity Department: John Wright (left) and Vic Vine (right).

Ken Phipps & John Saunders
Production Director Ken Phipps (left) and Machine-Shop Foreman John Saunders (right). The equipment they are working with is a Wild Barfield HF induction heater that was used for hrdening components such as the drive pinion and con-rod.

David Bennett
Sales Manager: David Bennett.

David Bennett & Ken Phipps
David Bennett & Ken Phipps outside the factory.

Making the Clark Scamp

These three gear shaping machines were used to cut the teeth on the drive pinion and the main gear.

Avery metal hardness tester
An Avery metal hardness tester being used in the Quality Control department to check the hardening of a rear wheel axle.

Ward 3CA capstan lathe
A crankshaft being machined on a Ward 3CA capstan lathe.

Production control
In pre-computer days, this peg-board was used in the Production Control department to keep track of what was going on in the factory.

The Drawing Office
The Drawing Office.

Clark Scamps
The first production batch of Scamps waiting to have their engines fitted.

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Road to Hell

by Mark Daniels

The Coprolite Run in 2011 was witness to an unprecedented Clark Scamp flash mob!  Among this demonic turnout were two Scamp motor wheels on display in the hall and eight bikes, of which four were green, three red, and one blue.  Half the Scamps remained on display, while two green, one red, and one blue were ridden at the event.  Our tale starts by following the exploits of these two little green devils along the Coprolite course…

Four Scamp riders in 2011
The four Scamp riders at the 2011 Coprolite Run.  [Photo: Kell McLean]

It was an extraordinary moment to have four Scamps leading out the run from the car park, then out along the route, though by the time we were approaching the two-mile marker into Kirton, other bikes were already starting to nudge ahead—Scamps it seems, may not be to everyone’s taste … just because they’re slow?

By the time we were heading around Gulpher Road there seemed to be more bikes pushing ahead and disappearing into the distance than there were left behind—err, where is everybody?

Approaching the end of Gulpher Road, my ‘Green-1’ was seemingly developing a bit of a rattling noise from the engine department, and stopping for a check-up before the Golf Course revealed one of the top-end studs had vibrated out of the crankcase, so continuing gently for the last mile, I cruised in to the Ferry Boat Inn car park at Felixstowe Ferry among the later arrivals.  A quick spanner check at this halfway stop re-tightened the stud ready for the return leg, so Chris Day on ‘Green-2’, and Dave Watson on ‘Blue’ had arrived before me, while Andrew Pattle on ‘Red’ became disabled with a rear wheel puncture, which is a major fix on a Scamp, so ‘Red’ was down and out.

The homeward trip on ‘Green-1’, V 10721 was more prudently navigated along the direct route at low speed to minimise the effects of further vibration-related issues, while Chris on ‘Green-2’ opted for the full course at full speed.

Joining up again with the other two Scamps on the road back towards Bucklesham, ‘Green-2’ U 11024 now had its front mudguard strapped to the rear carrier, apparently having vibrated out all its mounting bolts, until it fell down onto the wheel, and Chris had subsequently ridden over it!

‘Blue’, ‘Green-1’, and ‘Green-2’ completed the course, but vibration was certainly an issue.

The only way to reduce the vibrations was to ride slower…

Following the Coprolite Run, we performed further road tests and photo-shoots on both green Scamps.

Road test ‘Green-1’, VBJ 116F, Frame number V 10721 (frame numbers started from 10000)

Clark Scamp

This bike is fitted with a Dell’orto SHA 14/12 carburettor, whereas when we tested ‘Blue’ and ‘Red’ in the original Devil Rides Out article back in July 2007, both those machines were fitted with Amal 369/162 carburettors.

Starting is much easier with the Dell’orto carb, compared to the Amal as fitted to other Scamp models.  Click down the choke lever at the carb, just in front of the air filter.  Turn on fuel under the right side of the tank.

Clark Scamp

Switch the ‘power key’ (underneath the crankcase) into drive position to engage the starting pawl.  Hold in the decom-pressor lever under the left handlebar cluster, then pedal off.  This requires a certain amount of physical effort to maintain, since the decompressor venting doesn’t appear totally effective, but the engine readily fires with a light tweak on the throttle and is soon coughing against the choke, so open the throttle wide to automatically release the strangler latch, and Scamp gasps in a few good cylinders-full of air to clear its little lung.

Running quickly settles down to a crisp and mellow popping, with little tweaks on the throttle being responded to with eager little snatches on the automatic clutch.  Scamp seems keen to go, so we take off from the kerb.  The automatic clutch bites fairly readily, at which the high load and low revs situation makes Scamp’s motor suddenly appreciate that pulling off is going to represent more than it can manage without some assistance, so we help with a little boost on the pedals to get through the initial movement phase.

Once away, the exhaust tone clears to a flat drone, with a hopeful urge as Scamp gets stuck in to acquiring some pace.  Describing this as acceleration would probably be an optimistic term, as waves of vibration flood in through the pedals from 10mph, increasing in frequency as the revs creep up.  It soon feels very much like you’re receiving an electric shock through your feet!

Clark Scamp

The bike seems to get through the worst of these vibrations by the time its crawled a little past 20mph, so it proves better to settle for general cruising between 22–23mph (on pace bike tracking).  Though this seems fairly close to Scamp’s maximum on flat of 25mph, it’s not actually thrashing the bike to death since the revs are still relatively low, it’s just that the engine seems unable to pull much more against its final drive ratio.

With no speedometer fitted, the pace bike tracked our downhill run best at 34mph, but this accumulated speed readily dropped away against the following uphill gradient, right down to just 12mph, but ‘Green-1’ still doggedly crested the rise without resorting to pedal assistance.

It has to be said that the vibration (probably due to poor crank balance) was very tiring during our runs on this particular Scamp.  The only way to physically cope with our first couple of ‘impression’ runs of around 12 miles, was by riding the bike slower.  On the main test run after ‘holding off’ to warm the engine for the first couple of miles, the remaining three to four miles were ridden pretty much at full throttle.  The vibration on this main test run was particularly fatiguing, and made to seem all the worse during the trial by constant cyclic drumming from the reduction gear.  These effects also take their toll on the cycle parts as much as the rider.  Vibration on the first ‘impression’ run managed to completely lose one crankcase screw and loosen a second.  Completing the main test run found the foot of our side-stand had fallen out somewhere along the course!  Readers might be happy to know the pace bike retraced our tracks and found the missing part in the road about a mile from base.

Though the rear calliper brake slowed down the bike adequately, there was a number of complaining groans registered from the straining brake blocks.  The front drum brake proved more effective and less stressed in operation, but you generally wouldn’t want to rely on that alone.  A considered balance of the two brakes was certainly the best formula.

The original fitment Radaelli sprung mattress saddle is never going to be any contender in the sumptuous comfort competition, though it proved generally adequate for the more commonly short distances at the typical low speeds that the average Scamp rider might care to normally suffer the bike for.  When running at higher speeds, the vibration and constant road battering from the suspension-less frame will come right through and scramble the rider.

It appears that not all Scamps were born equal.  The variable quality of Clark’s machining and pot-luck crank balance could seemingly result in a number of shades of grey!

The lighting arrangement on this bike was converted to 15/15W beam/dip equipment with 3W tail, and the Dansi generator produced good light from both lamps, perfectly adequate for the bike at night considering the limited performance of the machine.  The Miller horn also produced an effective and easily audible tone.

It’s not very often we get to compliment effective electrics on old bikes we try—shame about the rest of the Scamp...

Road test ‘Green-2’, XDY 855H, Frame number U 11024 with Amal 369/162 carburettor.

The remarkable thing about this machine is it’s the only example we’ve seen fitted with a Huret speedometer set and marked as a 16×1.2 ratio Huret drive.  This was apparently listed as a genuine Clark accessory kit, and we’ve never seen a Huret drive like this ever before.  There’s obviously no question that this special Huret kit existed to specifically suit the 12/16” wheel size, but we can only wonder why Raleigh never offered the set for the Wisp?

Clark Scamp Clark Scamp

As a reminder how much ‘fun’ it is starting a Scamp with the Amal carburettor…

Here comes the Scamp

Pull on the petrol tap at the fuel tank, and the choke is … a strangler on the back of the carb down by the rear wheel!  No linkage control, and no throttle latch to release it; you can just bet this going to be awkward!  There is a primitive sort of tickle device on the carb, which comprises the top of the float needle sticking through a hole in the float chamber top.  You can press this to flood the chamber, though it doesn’t seem to offer any discernible advantage in the starting procedure, and a veritable disadvantage would appear to be as a direct access point to allow rainwater into the float chamber!

It takes several attempts before the engine does continue running, but then you’ve got to stop and dismount to open the choke shutter!  To stop it stalling (since we don’t want to go through the starting palaver again), the tendency is to keep it on the throttle, but the automatic clutch drags and the bike tries to make off down the road, so you have to hold on the front brake now, while you try and open the strangler with your left hand down by the rear axle!  This proves hopeless if you’ve made the mistake of dismounting to the left side, possible but awkward if you dismount to the right.  Once the choke shutter is actually open, it’s just as well to lift by the rack to get the back wheel off the ground and rev it a bit on the throttle to clear its throat.  Now the engine starts to run slower without dying out, so you can remount and finally get underway.

A lot of these starting difficulties would certainly have frustrated most customers, and it’s baffling as to why they ever sold machines fitted with the Amal carb?

Meet the Scamp

Since Huret speedometers can never be trusted to deliver accurate readings, the road test on ‘Green-2’ was accompanied by our pace bike.  Best on flat with tailwind paced 29mph (speedo bouncing between 32–35), downhill paced 35mph (speedo very ambitiously pinned around 40mph on the end stop), and the following uphill climb slowed to 14mph before cresting the rise on engine power alone (without any pedal assistance).

The Huret speedo presented fairly accurate indications up to 25 on the clock, above which the needle began to swing increasingly wildly, and became more optimistic in its indications, which were generally taken as an average on the swingometer.  There seemed fewer vibration issues with ‘Green-2’, and less rider impression of cyclic drumming than ‘Green-1’. There was also noticeably less transmission noise commented on by our pace rider, who was mostly following on the offside rear quarter.

Since our original Scamp articles: Devil Rides Out in July 2007, and its follow up Devil’s Epitaph in July 2008, we’ve added a number more items to the IceniCAM information service, including the full Coco v A.N.Clark Chancery Division 13-page legal account details (or five-page summary if you want the short version).  It’s certainly an interesting read, whether you agree with the final outcome or not.  From a technical point of view, Clark’s point regarding the wear rate of CoCo’s roller drive to the small 16-inch tyre was certainly very justified—drive roller induced wear would have been diabolical on a 16-inch tyre diameter.  Also much focus of the outcome of the case was based on specific aspects of the engine design, which (from an engineering point of view) seemed to have (questionably) played against Clark, since just about every variation the basic piston-ported two-stroke engine design had already been made by just about everybody, and there was nothing special about a bought-in proprietary two-stroke piston.

EMB Die-casting machine
An EMB 12B Cold Chamber Diecaster—
as used for casting Scamp crankcases.

The legal action didn’t change the reality that the engine was pretty dreadful.  From an engineering aspect, the pinion design to the ring gear required a difficult standard of machining precision (that ANC obviously couldn’t achieve), to prevent the cyclic drumming and vibration issues.  Quality issues with crankcases full of voids, suggesting the die-cast machines were not gas-boosted for the initial charge phase, and just relying on a slower hydraulic delivery.  Further, the tooling was possibly not equipped with suitable overflows to effectively vent the die, resulting in porous castings, which allowed the crankcase studs to pull out since they had insufficient material to anchor the threads.  The zinc cast clutch components, and starter pawl were all too frail and consistently failed, and we could go on, but you get the drift, so what’s the point?

Another interesting info file is the Scamp Accessories Leaflet, which lists and illustrates the speedo kit, but instead of the French-made Huret set, it shows a Dutch-made Lucia set!

The period advertising files are hysterical, ‘designed for women’ … ‘err, might that maybe put men off from buying it?’ …. OK, we’ll do a different ‘man’s’ advert too!  Period marketing, no idea…

There are now 25 historical and fascinating Scamp related archive files in our IceniCAM Info Service, all as free PDF downloads.

Next—If everything goes according to plan, then we might hopefully be having a Derbi Day, but I wouldn’t bet on it!

This article appeared in the April 2023 Iceni CAM Magazine.
[Text & photographs © 2023 M Daniels.

Making Road to Hell

Since the famous Clark Scamp flash mob was at the Coprolite Run in 2011, we could say this article has been twelve years in the making—but you may ask why we didn’t produce it sooner?

Following the Coprolite Run, some of the Scamps were displayed on the EACC stand at Copdock Show in 2011, then Green-1 & Green-2 were formally road tested and photo-shot in September and October 2011, before both bikes were subsequently sold on.  In the meantime a further Scamp project was underway to adapt a Watsonian cycle sidecar chassis to mount a Scamp motorwheel as a ‘pusher wheel’ that could be attached to a bicycle.

Mopedland completed all the metalwork to adapt and fit the Scamp rear wheel to the sidecar chassis, with an Atco lawnmower fuel supply tank mounted above the wheel, and mudguard brackets.  All the technical mechanics were sorted, and returned to the customer for finishing final assembly and fitting for operation.  This Scamp ‘pusher wheel’ cycle was subsequently supposed to come back to us for a feature and to complete the planned article, but the trail grew cold.  We presume the Scamp pusher wheel kit is still out there somewhere, and may turn up again some day … but after 12 years we finally gave up on the prospect of the intended article, and decided on this rewrite to clear the decks.

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