Sunday, January 03, 2010

'COPPERKNOB' REBORN

'Copperknob', certainly one of the most distinctive racing motorcycles ever, has been lovingly recreated and can occasionally be seen (and heard!) tearing around the back roads of Sweden. The orginal Ben Bickell machine sits on display at the National Motorcycle Museum in Birmingham, if you care to see it... but if you care to Ride it, you'll have to do what Urban Engstöm has done, and make your own!

The original Copperknob was built by Ben Bickell and his brother Joe at their Highgate, London garage, in 1929, from the bones of a salvaged Chater-Lea A.A. sidecar outfit! The former 'tug' frame soon housed variously J.A.P. single and twin-cylinder engines, and a rare Chater-Lea 350cc 'Face Cam' OHC engine. The lovely all-copper plate finish was purely decorative, although plating does show up cracks in tubing and metal plate.

The final configuration seen here uses a new-for-'31 J.A.P. 'Dog Ear' 500cc OHV 'track' engine, which the factory was keen to introduce to the racing fraternity, so sponsored a race at Brooklands with machines using this engine exclusively (and you thought the one-make race series was invented by BMW or Ferrari?). The April 1931 race was won convincingly by 'Copperknob' at 93.97mph. More success followed; in 1932 the gleaming machine laid down a 112.17mph lap during a Senior Handicap race at Brooklands, and averaged 99.61mph over 100 miles during a 'Hutchinson Hundred' race, in a driving rain. The gleaming copper plating on all steel body parts, combined with the history of track success, fixed Copperknob in enthusiast's memories. The motorcycle survived passage through many owner's sheds until the early 1960s,when it was completely restored, featured in several books, and displayed at Vintage Motorcycle events.

Here, Urban tells his own tale of recreating a machine which stirred his imagination:

"I was idly flicking through a copy of Classic Bike 2000 or 2001 (I think it was), and nothing much caught my attention until I reached page 30, and suddenly there was the bike which utterly transfixed me!
For me it was a piece of art, and I knew that I had to build a similar bike for myself.
As I am a professional artist and sculptor, so I have the tools and materials and time.
The bike was "finished" and ready to start in summer of 2005, and friends had been bending my ear for some time about how alcohol fuel was super-explosive, and how the whole thing would turn into a giant firework on the first kick!

We tried bump-starting but that didn't work...so one evening we designed a sort of roller starter thing - drag racing style- powered by the rear wheels of my old Volvo, and that did the trick!
She ran a bit rough to start with, then the revs started rising higher and higher and stuck at top rpm because the brass throttle had jammed.. So we spent most of the night having some beers and rebuilding the carb and, at around 6 am, I was able to treat my neighbours to a nice concert of JAP single music!

The frame and forks are from a 1929 Husqvarna TV50,
the front hub is from a 1940s Speedway bike. The engine is 1947 JAP sprint 500cc OHV with 1930s Amal track carb, BTH-TT magneto, three-plate one-spring clutch and Sturmey-Archer 3-speed gearbox.

I built the fuel tank, oil tank, foot controls, and the exhaust; a "Brooklands silencer". The engine runs on alcohol as in the old days.
Copper plating by Backmans Slip Sweden.

For me is Ben Bickells Copperknob the essence of a bike."

2 comments:

YJH said...

hey Paul, une pensée à Kumi, la femme de James Johnson_it was a year ago and I remember the cruelty of it

Grandpa Jimbo said...

What a great first photo. Hat needs to be turned round backwards. Then perfect.

i rmn & etc... Jim A.