The making of a star
As engine suppliers to the British industry, Villiers could, and did, sell any engine they made, but did this mean they became complacent?
If, for sake of argument, you made something which sold almost as fast as ‘it’ could be made, would you have any need or desire to alter, change or develop your product? Maybe not, why meddle with something which works, yes some variations may be needed to ensure the product was as compatible with as many markets as possible but major change…?
Such was the situation Villiers found themselves in as suppliers of engines to a considerable number of motorcycle makers in the UK. What they produced they sold, and if one maker didn’t want what was produced, or perhaps wanted something a little different, well, they could jolly well buy the basic unit and alter it themselves.
In actual fact as the Sixties dawned a number of makers were doing just such a thing and Greeves in particular would eventually twig how small a step it was to go from modifying someone else’s engine to making their own. The folklore surrounding Villiers’ attitude to those who wanted to gain more from their engines or hoped Villiers would be more amenable to providing what they wanted in the first place, is along the lines of “…this is what we make, like it or lump it…”
There are enough examples of this in period press reports to suggest it is true, they didn’t want to modify engines but temper this with a company working flat out just keeping up with demand. Perhaps Villiers didn’t do more than the minimum development work but to say they didn’t want to as opposed to not doing so, are two different ways to the same result.
Amid this situation there clearly were people at Villiers who wanted to embrace the new challenges brought on by first the European manufacturers such as Husqvarna, then ultimately the Japanese manufacturers. Such an engineer was Bernard Hooper who was instrumental in introducing the Starmaker engine to the public. When Motorcycle discussed the engine with Hooper they learned it was designed with
competition work in mind, making it likely the first engine the company had made in this way and for a 1960s 250cc two-stroke single produced a useful 25bhp at 6700rpm.
Exciting stuff, but there was more, in an era when not every large capacity sports twin road-burner had a carburettor for each cylinder and those so equipped had a novelty worth shouting about, this Starmaker unit had two carburettors for a single cylinder… gasp… phew! We know, hard to believe isn’t it. But why do such a thing? Just what benefit does fitting two carbs to a single cylinder actually bring?
Well, the main benefit is it makes sure the gas charge enters the engine at a constant high velocity no matter where on the rev range the engine is. Two carburettors do this by working not in unison but in tandem with one opening first and being followed by the second unit. To avoid an unbelievable amount of complication in the control of the throttle slides both carburettors work on one cable at the twistgrip end but at the other end is a special junction box to lift each of the slides at the correct time. The inlet tract was split into two and the inlet charge fed into the crankcase through a piston with separated transfer ports cut into the face.
Twin carburettors weren’t the only new development on this Starmaker unit, the gearbox too had been redesigned
In the world of two-stroke tuning it is desirable to have a high crankcase compression so the charge is pushed through the transfer ports and into the combustion chamber as quickly as possible. In the Starmaker unit the crank webs are full circle to aid primary compression while the webs are forged with the mainshafts, then the pair joined by shrinking in the crank pin. On the crank pin Hooper had specified a caged needle bearing big end in a con-rod of an ‘H’ section though rounded and slimmed to help with the gas flow, the little end has a gudgeon pin with a large cross section and this supports a domed piston. So far so good.
Once in the crankcases the crank is supported on either side by large roller bearings and on the drive side a needle roller bearing provides additional support in a high stress area. The crankcases themselves have strengthening webs cast in, these also aid cooling as does the massive finning on the barrel and head.
Interestingly from a prospective customer’s point of view, Villiers couldn’t be expected to know what every manufacturer had in mind for a frame design so provided the exhaust port situated so an exhaust could exit either side of the engine. Light alloy castings were used to produce the head and barrel but instead of casting the inlet tracts in, Villiers cut them using a milling machine which would be a slightly more expensive way of doing things but would guarantee the port shape followed the designer’s drawings accurately.
Twin carburettors weren’t the only new development on this Starmaker unit, the gearbox too had been redesigned and clearly attention had been paid to reducing friction in its operation. While it was still bolted to the back of the engine in Villiers’ traditional manner, inside the shafts ran on needle rollers rather than bushes and the taper on the cog engagement dogs encouraged them to mate securely.
Even the selector barrel had deeper slots milled in to ensure positive selection of the gears. Getting the power from the engine to the gearbox and on to the rear wheel is the primary drive’s job and this too had received the designer’s attention with some features not common to what the public thought of as ‘Villiers.’ The normal method to work the clutch would be using a pushrod against the centre button, however, the clutch was not of normal design, instead it was an all metal clutch with sintered bronze plates and a diaphragm type spring. The circular spring is fixed at the outer rim and when the centre is pressed the plates are free to move and gears can be changed.
The lifting mechanism too was not of a familiar type to motorcyclists of the time, it was a worm drive mechanism which was pulled into action by a cable inserted in the front of the chain case and the chief advantages of this whole system were said to be a constant clutch spring pressure with plate lift always in adjustment, unlike a three, four or more coil spring unit which can be slightly out of alignment. Oh, yes,
the spring pressure too was constant and reasonably light. Connecting this new clutch to the engine was by a duplex primary chain with a front sprocket which had its own ball bearing to run on.
Naturally all this stuff is no good unless the spark plug has a spark at the business end of it so Villiers used their flywheel magneto with a high-tension coil outwith of the engine to keep cool and a flywheel made from aluminium for lightness.
According to the press of the day, this Starmaker unit was a potential world-beater and yes, it did eventually make its mark and had a decent production life, but Greeves didn’t use it all that much and a couple of years after this launch the Thundersley company had its own engine sorted and fitted to their Challenger model.
The eagle-eyed will note this particular Greeves doesn’t have the twin carburettor set-up fitted to it and I wondered why. The bike had been restored in Sammy Miller’s workshops at his Bashley Manor museum in Hampshire, Sammy and Bob Stanley had rebuilt the bike for its owner Simone Cunningham to ride and the dual-carb set-up was not the lightest of things to operate. “It’s not always easy to keep in adjustment,” says Miller, “at the time I thought it unnecessarily complicated for the scrambles scene and maybe the works team could spend the time to keep it in tune, but the private owner? Maybe not so.”
So, Sammy fitted a single Concentric instead of the dual Monoblocs and it doesn’t look out of place. Speaking with Simone on the day she told me the Greeves had been bought part restored from up in the midlands and she’d brought it to Sammy’s to be finished and get it working. The information with the bike suggested it hadn’t had a lot of use and there were quite a few original bits on it which were saveable. Once in the Miller workshop Bob Stanley – at the time Sammy’s chief man in the workshop but now retired – cast a critical eye over the whole machine.
“To start with,” he said, “all the bearings and bushes were replaced and the bore checked out to see if it needed a new piston. It didn’t, so the engine could go back together quite quickly.”
The gearbox was in good order with a few bearings here and there to sort out, and, unlike some machines which have to be resurrected from the most dilapidated components, the biggest task on this Starmaker was to create a single carb inlet tract and check everything else over to make sure it was in good condition.
“We replaced fasteners where we couldn’t save them,” says Bob, “then there were things such as the original rims which could go back on quite easily, we just used stainless spokes and polished the hubs up.”
Inside the hubs are new bearings and brakeshoes but the spindles were sent for plating with the fasteners. “The sprockets and chain were replaced as were the tyres and cables,” Bob racked his memory for what had been done, “the front mudguard is original but the rear one is new, the handlebars and levers were reuseable, the seat came with the bike, we had to fully rebuild the front forks though, they were not in such good condition,” he added cryptically. Also unserviceable were the rear dampers, originally they would have been Girling units, now Girling sold up the motorcycle side of things to Alf Hagon a lot of years ago, the Girling name couldn’t be used but essentially the Hagon units are Girlings.
Also missing was the correct petrol tank for this model, the one fitted is a Greeves item but not the right one. Says Simone “if I had had a pattern I could easily have fabricated a replacement in our own workshops but this one will suffice for the moment.”
The distinctive exhaust and silencer too were missing but by a stroke of luck a chance comment brought to light a stockist who had one original exhaust and silencer left. Getting it turned out to be the easy bit… getting it to fit was slightly more involved… All Sammy and Bob would say was “…frame to exhaust port was tight…” then they talked about the weather. Once everything was fitted and the bike was working the whole thing was taken apart and various bits sent off to the paint shop for a coat of Moorland Blue, then a simple case of assembly and a final check over to make sure it was as good as it could be.
There was an intent by Simone to race the bike but the pandemic raging in 2020 curtailed such plans. It has also meant the bike has become surplus to requirements and is likely to be moved on in favour of the four-strokes which are her preferred engine configuration.