POR­CU­PINE REPLICA

Classic Bike (UK) - - Con­tents -

With real Por­cu­pines fetch­ing over £40k at auc­tion, AJS fan John Tay­lor opted to cre­ate his own replica

The AJS E95 Por­cu­pine isn’t a sight you see ev­ery day. Only four were built and such ex­ot­ica doesn’t come cheap. In 2000, an E95 sold at auc­tion for £157,700 and in 2011 Bon­hams bro­kered the pri­vate sale of one for around $675,000 (£418,000).

In the face of such prodi­gious prices, AMC en­thu­si­ast John Tay­lor, a 67-year-old who still keeps him­self busy con­struct­ing agri­cul­tural build­ings in the Lin­colnshire Wolds, took a dif­fer­ent ap­proach to ac­quir­ing such a ma­chine. “I’ve got an AJS 7R, a Match­less G45 twin and a cou­ple of G50 sin­gles,” he be­gins. “I thought it would be nice to have a Por­cu­pine as well, to com­plete the set. But I could never af­ford an orig­i­nal, so I de­cided to build a bike that looked like one in­stead.”

He’s just fin­ished it, and I en­coun­tered it at a small club event 10 miles from John’s home. “I de­cided to bring it along to see how it goes,” he ex­plained. It went al­right, al­though the Por­cu­pine looka­like was never go­ing to chal­lenge real sprint bikes over the quar­ter mile.

“It’s over-geared at the mo­ment,” ad­mits John. “I need to put a big­ger sprocket on the back wheel to give it bet­ter ac­cel­er­a­tion – even at my age I want pick the front wheel up when I go over the Moun­tain at Cad­well!”

Once the sprint was fin­ished, there was more time to talk to John at his farm­house work­shop. “Af­ter a long day’s work, build­ing mo­tor­cy­cles is the best way to un­wind,” he ex­plains. “As soon as Em­merdale comes on the telly, I say to my wife: ‘Right, love, I’m off up the work­shop for a while...’”

Al­though he is clearly a big fan of AMC race bikes, he’s not just a col­lec­tor. His son An­drew won the Clas­sic Rac­ing Mo­tor Cy­cle Club’s 350cc and 500cc GP Sin­gles Cham­pi­onship in 2011 and again in 2012, usu­ally rid­ing Manx Nor­tons pre­pared by spon­sor Tony Dun­nell. Mean­while, John pre­pared the AJS and Match­less sin­gles that took An­drew to sev­eral wins in the

Lans­downe Clas­sic Se­ries for orig­i­nal-spec pre-1963 race bikes. “That nice Aussie chap Cameron Don­ald part­nered An­drew on my G50 for the Barry Sheene Me­mo­rial Tro­phy at Good­wood in 2011,” says John. “We had a prob­lem with the bike on Sat­ur­day, but Cam won the race on Sun­day!”

John’s plan to make a Por­cu­pine looka­like started to take shape when he found a Laverda 750SF en­gine. That’s right – a Laverda. “Like the E95 en­gine, the Laverda is a unit-con­struc­tion twin with in­clined cylin­ders and the fi­nal drive on the right,” he ex­plains. “I had a spare G50 frame in re­serve, in case one of the race bikes was da­m­aged, so it didn’t take me long to check if the SF en­gine would fit.” You need to be com­mit­ted to build­ing your dream bike be­fore you reach for the hack­saw and start cut­ting the twin down­tubes from a per­fectly good Match­less frame. But John didn’t think twice. “The down­tubes had to be re­placed with oval-sec­tion tube,” he says, “and, of course, the front of the frame is much wider.” Both tubes which run from the nose of the sad­dle to the swingarm gus­set plates are unique to the Por­cu­pine frame and are also oval, but the tubes run­ning un­der the en­gine are round sec­tion. The forks are stan­dard G50, while the rear dampers are AMC’S fa­mous ‘jam­pots’. As John pointed out, the jam­pots were never very good and none of the fac­tory rid­ers wanted them, but AMC paid their wages so they didn’t have much choice. The rear wheel hub and brake were cast in mag­ne­sium us­ing the orig­i­nal pat­terns. “I sent the pat­terns to UK Rac­ing Cast­ings in Kent (uk-rac­ing­cast­ings.co.uk) and asked them to make me three sets, so that I had a cou­ple of spares just in case. The cast­ings were ma­chined by a chap in the Mid­lands who used work for As­so­ci­ated Mo­tor Cy­cles. He also ma­chined the brake for Rob Ian­nucci’s Team Ob­so­lete bike, so I couldn’t ask for bet­ter.”

John then made a dolly and pressed the al­loy cov­ers that fit on the right side of the hub. “The pat­terns for the cor­rect twin-lead­ing-shoe front brake didn’t sur­vive,” says John. “The brake drum should have six cool­ing fins – but those are very hard to find, so I used one from a G50 to get my Por­cu­pine run­ning.” He strolls over to a cup­board at the back of his work­shop and reaches in­side. “But I man­aged to buy one a few weeks ago. It wasn’t cheap...”

To make sure that his looka­like was built to scale, John had a friend print pho­to­graphs of Rob Ian­nucci’s bike that were half life-size, us­ing the 20in wheel rims as a ref­er­ence. And that was im­por­tant when it was time to make the Por­cu­pine petrol tank. Hold­ing a mas­sive 6½ gal­lons, it’s in­stantly recog­nis­able and a

work of art. So who made it? “I did,” says John, with so much mod­esty that he al­most blushes. Amaz­ingly, it was his first at­tempt at metal bash­ing.

“Be­cause I build agri­cul­tural build­ings, I of­ten have off-cuts of 75 x 225mm tim­bers. So I screwed and glued them to­gether,” he ex­plains. “When I had a block of wood that was big­ger than the tank, I at­tacked it with my chain­saw. Then I got to work with my plan­ing ma­chine and fi­nally filled and filed it with a hand sander so that it was per­fectly smooth.”

John’s next move was to get an alu­minium sheet, lay it over the wooden ‘buck’ and start beat­ing it into shape with a rub­ber ham­mer. “I used four sheets to make the top of the tank,” he says, “and when I was happy with the shape I welded them all to­gether.”

Mean­while, John had dis­patched the SF en­gine to Keith Nairn of Laverda Sco­zia (laver­das­co­zia.co.uk) who sig­nif­i­cantly light­ened the crank to bring it to SFC race spec­i­fi­ca­tion by ma­chin­ing away more than 4kg of metal. Keith also cut off the starter clutch and dy­namo drive – the looka­like would be bump-started like a real Por­cu­pine – and fit­ted Car­rillo rods and his own forged pis­tons, be­fore dy­nam­i­cally bal­anc­ing the crank. “I worked on the head my­self,” adds John, who also fit­ted Miku­nis in place of the orig­i­nal Dell’or­tos. When Bri­tish Rac­ing Mo­tors (BRM), the For­mula One car con­struc­tors based in Bourne, Lin­colnshire, sold much of the fac­tory con­tents, John was able to buy sev­eral sheets of 10mm thick mag­ne­sium al­loy. “I cut those into the shape of the gear­box and en­gine cov­ers,” he says. The ‘Por­cu­pine sump’ is a sheet of alu­minium al­loy that was beaten into shape on a lump of wood. It is mounted in front of the Laverda’s sump, and acts as a catch-tank for the en­gine breather pipe. Check out the cam box cover that you can see be­tween the front down­tubes of the frame; it’s made from an al­loy tube. John used his lathe to ma­chine the cool­ing fins, then cut the tube in half length­ways and welded one piece to an al­loy box. “Look closer and you can see oil pipes lead­ing to it,” says John. “It might look like a Por­cu­pine cam­box, but it’s ac­tu­ally an oil cooler for the Laverda en­gine!”

An­other bit of fak­ery is the out­board clutch. “This one is a mod­i­fied Honda 500 clutch,” ex­plains John. “It doesn’t trans­mit the power, of course. The Laverda clutch is in­side the en­gine.” He made his own ig­ni­tion sender sys­tem us­ing In­ter­span com­po­nents, and hid it be­hind the disc that’s in front of the clutch – on the orig­i­nal bike this was the geared pri­mary drive cover.

“That disc started life as a 180mm back­ing plate for an an­gle grinder. It was a rush job,” con­fesses John. I spent 18 months work­ing on my looka­like and I just wanted to get it fin­ished.”

So is he happy with his Por­cu­pine? “Build­ing this bike given has given me a lot of plea­sure,” says John. “It turned out bet­ter than I ever hoped it would. Now I want to put some miles on it be­fore I take it to Cad­well. There’s a moun­tain there I need con­quer!”

‘REAR WHEEL HUB AND BRAKE WERE CAST IN MAG­NE­SIUM US­ING ORIG­I­NAL PAT­TERNS’

RIGHT: John also pre­pares his bikes for son An­drew to race in the Lans­downe

BELOW: John in his work­shop, a place to wind down and avoid Em­merdale

Lo­cal sprint meet was a test run for the bike. John wants lower gear­ing so he can hoik the front wheel over the Moun­tain at Cad­well ‘Cam box’ be­tween front down­tubes is an oil cooler for the Laverda en­gine! Rear dampers are no­to­ri­ous AMC ‘jam­pots’

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