ALLEN MILLYARD MACHINES
John Nutting rides some of the best specials ever built.
WSpot the pots, all 18 of them! A spectacular array of the Millyard multitudes with the 350cc four on the left, a 666cc five, the 1026cc four and an 850cc five.
hat if Kawasaki had developed a range of four-cylinder air-cooled two-strokes in the 1970s, rather than the triples that became the factory’s signature? It must have crossed the minds of the designers and most likely the marketing people would have gone for it, but the bean counters would have kicked the idea into touch on the basis of cost. That was a mistake, and I know it was because I’ve ridden a 350 four-cylinder Kawasaki and it’s better in every way than the S2 triples that were sold. It’s one of the latest of a long line of multicylinder Kawasaki two-strokes that have been built by Allen Millyard and it’s quite brilliant. Allen has rightly earned his legendary status as the creator of amazing machines such as the 500bhp Viper V10, the vintage-styled five-litre V-twin Flying Millyard, both of which were featured in Pip Higham’s articles in CMM last year, not to mention his epic V8 and V12 Kawasakis. But he still likes small bikes because they are less likely to attract the unnecessary attention of the local constabulary and are simply more pleasant to ride in their powerbands. This is why one of the most recent of his projects has been to build a trio of four-cylinder two-stroke 350 Kawasakis based on the S2 model from the 1970s. Like most of Allen’s specials they use his signature technique of adding an extra cylinder (or sometimes two) to the familiar three-cylinder
Kawasaki format to create a machine that might have emerged from the factory in Japan. So faithful are they to the factory bikes, that at first glance they appear to be well-restored originals: until you see the extra pot/s neatly slotted into the chassis. His Kawasakis have been renowned since the first, a 415cc five-cylinder, picked up an award for the bike with the best technical interest at the Stafford Classic Mechanics show in 1996. Yes, Allen has been building these two-stroke Kawasaki specials for more than two decades, the latest bringing the total to more than 30. They are dispersed around the world and are a testimony to Allen’s creative ingenuity and attention to detail in that many have covered up to 20,000 miles. These are not just bikes for display. They are robust enough for daily use. Indeed, Allen’s first 415cc five was used as his daily transport back in the 1990s, summer and winter. I must confess to have long disregarded his Kawasaki multis as impractical attention-grabbers best suited for bar bragging. Yes, they were clever, but what use would they be on the road? Seeing the 350cc four taking shape on Allen’s Facebook pages alerted me to the possibility that I might be mistaken. So I called him up to blag a ride and find out the truth. Allen was happy to oblige, and I entered a world of fantasy motorcycling that turned my misconceptions upside down. I also discovered a one-off character who makes a mockery of the description of an ‘ordinary man with extraordinary skills’. Allen could be like many who have worked through mechanical engineering apprenticeships but he has several extra layers of intuitive craft skills and a three-dimensional vision that enables him to turn a collection of corroded, dusty components into a mobile art form. And all in your average garage with the most basic of tools. The 350 four distils everything that Allen has learned over the past two decades into a practical road bike. He says that he prefers this bike to his bigger more testosterone-packed machines which in most circumstances on the road are only scratching the surface of their performance potential. It’s also better than the original S2. That’s because the engine is smoother, more lively and can be ridden through a more pronounced power band, revving up to 8000 with ease. The engine is based on a 249cc S1 to which Allen adds a fourth crankcase and cylinder. The 1mm-oversize pistons and air-cooled cylinders are stock – Allen tends not to ‘tune-up’ his engines – along with the 22mm-bore Mikuni carburettors. With the cylinders re-bored to match the pistons, the internal dimensions are 46 x 52.3mm giving a capacity of 347cc, just shy of the S2 triple’s. The bike is also beautifully finished with the rolling chassis and painted items looking like factory originals. Even the intake plumbing looks authentic: though it’s actually made up of household plastic waste pipes covered in black shrink tubing, and is fed from a paper air-filter between the side-panels. The exhaust system is Allen’s own fabrication in stainless steel. Amazingly, the four muted expansion chambers are designed more for their fit than their performance, yet they work just fine, without any interference with cornering clearance. The engine fires up easily on the kick-starter with a much busier ‘pockety-pockety’ sound and responding cleanly to
the twistgrip, which is no heavier than the original, despite the additional cables. Part of the reason behind the reliable operation is Allen’s preference for using battery and coil ignition. He makes up a special plate for the end of the crankcase to accommodate four contact breakers and their associated capacitors, all of which are OEM and much more reliable than cheap copies, says Allen. “Coil ignition gives a fatter spark from zero revs and the way I set them up have lasted for thousands of miles,” he says. Key details are a dab of locking compound under the base plates to stop them moving and silicone to stop the wiring chafing under vibration. Not that there’s much of that. Allen builds up the crankshaft on the fours so that the cylinders fire at 90º intervals, rather than ‘big-bang’ as was used on the only inline four-cylinder two-stroke made in reasonably high volumes, Yamaha’s TZ750. On a racer, Allen’s arrangement might be seen as a ‘screamer’ but with modest tuning it feels silky and responsive, and adds a touch of quality. Sitting on the bike you’d be challenged to think it anything but an original S2, with the instruments and controls feeling light and smooth. It’s only when you glance down to see that the outer pots are more easily visible that the game is up and you know you’re on something special. The engine is moved across to the left with minimal alteration to the frame, using spacers and longer mounting bolts, and no rubber mounts because they’re unnecessary with the better balance of the crankshaft. To bring the drive sprocket back into line, Allen uses a ‘bell’ sprocket of the type often used on drag racing machines. This extends the alignment by the width of half a cylinder, the extra side-load on the gearbox output shaft being carried by an outrigger bearing supported by an unseen bracket bolted to the cases. The 350 four’s extra width is less than about 50mm on each side across the outer covers and much less across the gearbox, so there’s less need
to modify the foot controls, and likewise the kick-start lever. Many bikes from the Seventies often betray their heritage, even when restored to perfection, with bouncy suspension and poor grip from skinny tyres. Allen’s 350 four felt much more taut than I’d expected with much better grip from the modern, slightly wider, Avon tyres. My lasting impression of the four-cylinder engine was its smoothness, in contrast to the buzziness of the original S2 and KH400 triples. With slightly lower gearing – Allen fitted 43/16 drive sprockets rather than the 37/14 originals – the bike should in theory be capable of slightly more than 100mph. At around the legal limit it was revving at 5500 with plenty in reserve and was a delight to ride. Allen doesn’t make his machines specifically for sale. If however after he’s ridden a few thousand miles – which he often does – he’ll accept an offer, which is why there is a happy band of owners who are privy to the secret of Allen’s mastery of engineering. While I was riding the 350 four, two of them promptly turned up with two examples of Allen’s five-cylinder machines: Sam, one of his two sons with a 666 based on a KH400 and friend Pip Davidson with his 850 based on a KH500. I was spoilt for choice. During the photo session, Allen had been riding his 1026cc Kawasaki four, based on an H2 with an extra cylinder and 1mm-oversize pistons, which he offered to me with a knowing grin. One of the earliest of his rare commissions in the late 1990s had been by an American who wanted an H2 four to add to his collection, and Allen goes out to California every year to service it. One day they were out riding in the desert with none other than racer Doug Polen on his 888 Ducati. “The Kawasaki out accelerated the Ducati and went off the clock at 150mph,” said Allen. With this in mind I set off. Yes, it was a bit of a lump compared to the 350 four, but the tractor-like torque was even more intoxicating than on a 750 triple and because there was no need to rev it the machine felt much smoother. Another aspect to deal with was the gearbox, which has a neutral below bottom gear to remember, unlike the more conventional 350’s five-speeder. This all paled into insignificance when it was opened up in anger as the front wheel pawed the air and the scenery shot by in a blur. Riding slowly in traffic required a knack as well, because the engine tended to hunt, but the trick was to pull a higher gear than normal to load the engine. Pip’s 850 was different altogether. With the five pots chiming in at 72º intervals it was turbine smooth, with power akin to the early Mach III, only with much, much more of it. I was gasping for breath and relieved to return the machine in one piece. But as if to emphasise that these machines are practical to use, they are regularly taken on group ride outs.
How did it all start?
Allen is 56, married to Tracey with two grown-up sons, and has been retired for six years. He’s built special bikes for most of his life, starting out by fitting a 150cc mower engine into a moped and then at 15 grafted a Mini car engine into a BSA Bantam chassis. “I was really interested in metalwork at school so I could use the lathe and the welder and stuff, the milling machines and grinders,” he recalls. “By cutting the Bantam frame in half and bolting it onto the engine I built the bike up and got it running. I got caught by the police riding it so my dad told me to break it up!”
His skills with hand and machine tools come from an engineering apprenticeship with the MOD that led to a career in instrument and toolmaking. “You would spend six months just on filing, every day, eight hours a day,” he says. “As a toolmaker you’re taught to do everything straight and square without having fancy tools. With a hacksaw if you can cut a straight line within ten thousandths of an inch you can progress to the next stage of your training. So I was taught to cut things straight. That gave me the core skills to manipulate metal. Then I went to college and got my HNC in mechanical engineering which gives the technical background as well, such as stresses and strains and finite element analysis, what works, what doesn’t work, what materials, things like galvanic corrosion, all the stuff that goes with that. So that’s built into me. I never do or rarely do calculations or final drawings. I just know what will work and what will not work and how far you can take something.” One of the first specials that was recognisably a Millyard was a Malaguti moped with a 180cc V-twin engine made from two C90 Hondas. “I’ve still got the engine in the shed actually,” he says. “Then I got married, got a house and had children and I had a boring red VFR750J in 1989 on an F-reg which was all I could afford. Then in 1996 I got bored with changing tyres, topping up oil and polishing the Honda so I decided to sell it to pay off part of the mortgage and bought a Kawasaki H1 for £300.” Although it was a runner Allen found it needed a crankshaft service but didn’t want to pay for it. “I didn’t have a hydraulic press so I made a jig out of some clamps and some screws and was able to strip the crankshaft down and rebuild it.” Then a 250 Kawasaki S1B turned up. “It was in bits, completely wrecked and rusty,” he says. “So I said: I’m going to convert that one into a five. So I had the standard 500 H1 that I rode around as my everyday bike and then I made this S1B 415cc five-cylinder which was featured in CMM in 1996.” Then Allen decided to modify the 500 Kawasaki, and used the 415 five as his daily hack. “I used it all through the winter, in the rain and snow, took the children to piano lessons, did the shopping, every day because it was the only bike I had that ran, while I converted the 500 into an 850 five.” Allen was in the Isle of Man in 1997 with the 850 five when he first met American Daniel Schoenewald, who was so impressed he ordered a 1000 four. A 1973 750cc H2-A was shipped to the UK and the bike completed and flown back the following year. “Three weeks later he called me and said he was sending tickets so I could go out and commission the bike. So the whole family went out to Los Angeles for three weeks,” says Allen. “He’s still got the bike today. It’s done about 15,000 miles and I still service it each year, mostly cleaning the carbs because the fuel is so bad.”
What’s the engine-building process?
Allen doesn’t need much in the way of machine tools to cut and shut his engines. It’s all in the craft skills he’s acquired. “I could go to someone’s house and build one of the bikes in their shed,” he says. “I need a vice and a bench, hacksaw, some files, and ideally a small lathe but I can cope without one for doing fivecylinder conversions.” Allen continues: “I take the engines apart then get everything vapour blasted at Doug Cox in Reading who brings me back these beautifully clean engine parts like they’ve been made yesterday. So then I can scratch the lines on with my scribing block and cut down with the saw. “I don’t have a band saw because I wouldn’t use it often and it would take up space I haven’t got. The hacksaw just hangs on the wall! The blade has 18tpi for aluminium and I gently cut the cases in half. The more accurately you can cut them the less machining is needed. In the old days I used to finish with a file, but now I’ve got a mill so it takes five minutes to mill off the cases to the right height. I always cut 1mm plus metal then machine that off. If I need extra metal I use a shim weld and it fuses
all together. The tolerances are not great: if you measure between the cylinders on the Kawasaki they vary up to a millimetre anyway. It’s not that accurate and the stud holes have to be slack. “To make the crankshaft bearings align I’ve turned up a big lump of steel I’ve had for years and this rests in the crank bearings. I clamp it up really tight, and bang it together with a hide mallet. The trick is that you mustn’t have any gaps. If you have any gaps in the joints the weld will pull and will distort the engine. If there’s a gap I’ll put a shim in it, say ten thou’, then hammer down aluminium sheet to that thickness and bang it in the gap. It’s called shim welding and is an old technique. In the early days some of the engines were distorted but they still worked. When you did it up tight it all pulled straight. The way I Tig-weld them, they’re pretty much spot on and the crank spins just like that.” Allen says the bikes he builds are for himself: “If somebody wants to buy the bike I’ll sell it. I don’t like to do commissions because then it’s stress. I also like to do thousands of miles on them before I sell them.” There’s often left-over engine parts after Allen has completed a project. That’s how the 500cc Kawasaki twin he built in 2016 came about. Interestingly, he needed to make one half of the engine narrower rather than wider, and realised that when the original three-cylinder engines were designed they were based on the earlier 350cc disc-valve twins but with an extra outrigger bearing. That was cut off and created an engine that was slimmer than Suzuki’s Cobra 500cc twin! Fitted in a KH400 chassis it’s; “much more light and lively than you’d expect,” says Allen. cmm