The Shape of 100mph


Bob McIntyre bagged the first 100mph lap of the Mountain course on the Gilera 500-4 in 1957’s Senior TT.

A replica of the ground-breaking bike will be at this year’s Classic TT


The Shape of 100mph

An article for Classic Bikes by Mike Nicks  Photos by Tim Keeton and the Bauer Archive


The Shape of 100mph



The 2017 Classic TT will pay tribute to Bob McIntyre's historic achievement


We look at the Kays’ replica as it joins the party...


The motorcycling world knew before the 1957 Senior TT that if the roads remained dry, a 100mph lap would probably be set for the first time in the history of racing on the Mountain Circuit. Geoff Duke had come within a fraction of it on his factory four-cylinder Gilera in 1955, when he achieved 99.97mph.  That bike had just a handlebar fairing, but for 1957 it was equipped with one of  the most beautiful shapes ever created - Gilera’s final version of its so-called ‘dustbin’ fairing.

Dustbins, which fully enclosed the front wheel, had first appeared on Grand Prix grids some four seasons earlier.  Their advantages were obvious - better wind penetration and higher top speeds- and it was reckoned that such streamlining increased a bike’s top end by some 10-12moh.  Disadvantages? A dustbin could be dangerous in side winds, placed greater loads on hard-pressed drum brakes, could rob the front brakes of cooling air, and a poorly-designed version might provoke front-wheel lift.


To counter this, cutouts under the nose of Gilera’s 1957 streamlining assisted in brake cooling, while side scoops fed air to the four Dell’Orto carburettors. Armed with the works bike producing 60-75bhp at 10,400rpm, Scottish rider Bob McIntyre recorded 101.03mph on the second lap of the race, and lifted this to 101.12mph on the fourth.  McIntyre, then 28, won the Senior TT, and the Italian Libero Liberati won the 500cc world title.  The Gilera four was the equivalent in its era of today’s 1000cc, 250bhp(ish) Honda RC213V in MotoGP.



Looking at he Kay MV Agusta engine - Great Engines in Bits


gifThe Kay Gilera 4 500



Bob McIntyre's 100mph lap in 1957 is the goal for 2017 on a replica Gilera



A celebration of the Mountain Circuit’s first ton-up lap was therefore a must for the 2017 Classic TT.  And who better to provide an appropriate bike than the West Midlands’ Kay family, who just so happened to have made a replica of the 1957 Gilera 20 years earlier.  The Kays - Mitchell, dad Mark and grandpa David - and their Black Eagle Racing team are synonymous with replicas of race bikes made by Gilera’s contemporary rival, MV Agusta, and have won three Classic TTs with their triples.  Mark Kay told Classic Bikes the story.

“An Italian collector, Alessandro Altinier, who knew what we were doing with our road bike MVs, turned up in a Mercedes-Benz estate car with a 1953 Gilera four in the back.  It looked perfect, as though you could get it out of the car and start it, but there were very few engine internals.  We had one valve, a bucket and a spring and piston, but no camshafts.  There was no gearbox or gears for the camshaft drive or primary transmission, but there were some drawings.  The cylinder head casting was old, and cracked everywhere.

“Alessandro said he wanted to keep the original crankcases, so we had to get the parts out in order to weld up the cracked crankcase.  We made new pattern equipment and castings for the rest.  We knew the centres for the valves and the distance between the crankshaft and gearbox centres, so we reversed-engineered it and got the bike to run.

Bob McIntyre

Bob McIntyre 1957

The Kay's Gilera 500 replica will aim to equal the 100mph lap record 2017 at the Classic TT


Bob McIntyre records the first 100mph lap in 1957

“A year later, Alessandro came back with a 1957 machine and asked us to do the same.  We proposed a deal with him - if he paid for pattern equipment, would he let us do a batch of replicas?  We already had the the cams, cam gears and cam profiles, so it would be quite easy to do.  We  made six bikes in total, including ours.  Sammy Miller was the first one to put an order in for his museum, in the late ‘90s.

“We built our own bike in 2004, and took it to the Classic Manx Grand Prix that year, just to prove the engineering.  But the magneto let us down - we were forever changing the points and the rotor arm, and ended up going around all the car places in the Isle of Man looking for parts”


The team returned to the Classic Manx in 2005, and rider Pat Sefton, a former British hillclimb champion and winner of the 1989 Newcomers Lightweight Manx, finished seventh, with the bike equipped with electronic ignition.  His fastest lap was 99.97 - exactly the same as Geoff Duke had achieved 50 years earlier.  This is the bike that will now be used as the focus for celebrations of the first 100mph TT lap at the 2017 Classic TT.  The 1957 Gilera four looks a familiar piece of motorcycle engineering to modern eyes, yet certain elements of its design seem oddly dated.  It was the first successful across-the-frame four, and you can see its lineage in Valentino Rossi’s Yamaha YZR-10R that reigns in World Superbike racing.  If you’ve ever bought a Honda CB750 or a Suzuki GSX1100 - or any Japanese transverse four - this Gilera is its grandaddy.

The Gilera was the first four cylinder bike to win a world road racing championship, in 1950, and it went on to amass a total of six titles in the 500cc class.  The replica for the Classic TT next August represents history in the biggest sense of the phrase.


The Kay's Gilera 500 replica will be raced in 2017 at the Classic TT


Yet its engine has a bore and stroke relationship of 52 x 58.8mm, reminiscent of pre-war long-stroke bikes There are twin overhead camshafts - just like the YZR-M1 and the ZX-10R - but they only activate two valves in each cylinder.  Designers of the time were too occupied in solving problems of valve-spring and piston reliability at engine speeds of 10,000rpm to take on the complexities of four-valve cylinder heads.  That was left to Honda in the 1960s.


Another old-world feature of the Gilera is its wide valve angle of 100 degrees.  Engineers would soon learn afterwards how to narrow cylinder head valve angles to achieve a more compact combustion chamber shape, but with this set-up the Gilera’s output was far ahead of the 54bhp that the Manx Norton, the epitome of the British racing single, could muster.

The Gilera relies on air cooling: its cylinders are canted forwards by 30 degrees to direct the breeze to the cylinder heads.  A characteristic of Italian design at this time was to use the oil sump as a form of cooling aid , which explains the elegant finned casting beneath the engine.  Drive to camshafts is by a train of gears, running between cylinders two and three. It is said that Geoff Duke, Gilera’s world champion from 1953-55, ‘Nortonised’ the Italian machine , moving the rider’s weight forward . 

It is hard to see evidence of that, however, if you look at 1957 photographs of Libero Liberati , who had his backside perched directly over the top of the almost-vertical rear suspension units as he raced to victory in five of the half-dozen championship rounds.  Perhaps that was just down to his own personal taste.  Whatever, the Gilera is a long, low and gorgeously beautiful motorcycle.

The German owner of the donor Gilera had brought with him a fibreglass replica of the original dustbin fairing, so using this as model, the Kays had one made in hand-beaten aluminium, like they were in the ‘50s.  It weighs 10.5 kg (23lb) - perhaps another disadvantagee of the dustbins.  This was hanging in their garage for 20 years, until the call arrived about next year’s Classic TT.

The Kays are the kind of people for whom life is lacklustre unless there’s a challenge in the air.  So as well as running three MV triples and a four in the 350 and 500cc Classic TTs next year, for three different riders - Michael Dunlop, Dean Harrison and Lee Johnson - they intend to both parade and race the Gilera. The first objective will be to get the bike through practice and onto the grid for the 500cc race on the Saturday (August 26th 2017). 


The Gilera 500 replica will be raced in 2017 at the Classic TT


Gilera 500


Their engine gives 54 bhp at the crankshaft, so it is not a podium contender against the more modern MVs and Paton twins.  The dustbin fairing is not legal for the race - the FIM banned them after 1957 - so the bike will be run with a dolphin version.


Bob McIntyre 1957




“We’d just like to set a 100mph lap on his 60th anniversary, and perhaps get into the top ten,” Mark says, “We’re looking for a rider who has the speed, but he also has to be sympathetic.”

If the bike can withstand 300 miles or more of practice and racing, it will go to the Jury Festival on the Sunday.  Current TT lap record holder Michael Dunlop will then ride it, with dustbin, in the Lap of Honour on Monday.  If the Kays can achieve that, as well as cope with the demands of their MV programmes, it will be a tribute to their talents and also to the enduring excellence of the Gilera’s design.



The Kay Gilera will be raced in 2017 at the Classic TT

Here we look at Kay MV Agusta engines - Great Engines in Bits