Tonkin Tor­nado

A road Manx

Old Bike Australasia - - CONTENTS - Story Jim Scaysbrook Pho­tos Rob Lewis and Jim Scaysbrook

From the time he learned to ride on a rigid frame 500cc Match­less, be­fore he was old enough to gain a road li­cence, mo­tor­cy­cles have been Steve’s chief in­ter­est. From a BSA Bantam, a 250 Match­less and a 350 Tri­umph, he pro­gressed to a se­ries of Ve­lo­cettes, cul­mi­nat­ing in a brand new Thrux­ton. But when the rac­ing bug bit in 1971, the Thrux­ton had to go to fund his track tackle – a 750cc Nor­ton At­las en­gine in a 1954 Feath­erbed frame. He was very suc­cess­ful on the Nor­ton, which gave way to a Mk4 See­ley Com­mando on which he scored nu­mer­ous suc­cesses and es­tab­lished him­self as one of Britain’s lead­ing rid­ers. “In those days we used to race up in the north of the coun­try at Sil­loth, Croft, and Cad­well, they were the three as well as Scar­bor­ough, which was prob­a­bly my most suc­cess­ful cir­cuit. I used to go there know­ing I could prob­a­bly win. It was in­cred­i­bly nar­row, they had to put the side­car onto the grass to pass. I went to the Manx GP in 73 on a TZ350. My spon­sor at the time was Den­nis Pratt, who had been a very suc­cess­ful racer on Nor­tons. In 1973 there was no New­com­ers Race at the Manx so I en­tered the 350 GP and fin­ished fifth, and best new­comer. I wanted to do the Manx again in 74 be­cause I would have won it, but Den­nis wanted to do the TT so we did, and as it turned out, it was a year too early as I fin­ished 22nd in the Ju­nior TT.

I did the TT for ten years on all sorts of bikes, 250 and 350 Yama­has, Arm­strong, Cot­ton, Du­catis and Guzzis for Sports Mo­tor­cy­cles, and won the Ju­nior TT in 1981 on an Arm­strong.” So how did a for­mer TT win­ner end up build­ing cus­tomer clas­sics? “I’ve spent the last 23 years restor­ing bikes and I fan­cied a change. I like build­ing bikes. I’ve done two G50 road bikes, an Mk2 and a Mark 3 See­ley, I did a See­ley Gold Star, and now I am onto the fif­teenth Manx Nor­ton, with an­other five to build at present. The bike (the Tonkin Tor­nado) is to 1963 Manx spec­i­fi­ca­tions, with stan­dard bore and stroke (86mm x 86mm), com­pres­sion is low­ered, with stan­dard cams. There’s an elec­tronic de­com­pres­sor which is ac­tu­ally a Har­ley-Davidson unit; a so­le­noid opens the valves so it kick starts eas­ily. There’s a long shaft on the drive side to ac­cept a stan­dard Bri­tish Lu­cas al­ter­na­tor, and I’ve used Amal Mk2 carbs on all the bikes so far, but Amal are not do­ing any more 36mm carbs, so the next bikes will use Mikuni car­bu­ret­tors. It has a Quaife five-speed close-ra­tio gear­box with a kick­starter, NEB clutch and belt pri­mary drive. It has a high first gear but once you get go­ing, I wouldn’t have any trou­ble rid­ing through Mel­bourne. Back in the rac­ing days the Manxes all suf­fered from “mega­phoneitis”, whereas the two G50 road bikes I built, you could have rid­den them around the work­shop. It has a BTH mag­neto – a mod­ern mag­neto with no points, it’s elec­tronic with a re­mote coil, like speed­way bikes. In­stru­ments are Smiths repli­cas which come from Was­sall in UK and they get them from the far east some­where. I have used them for 12 years and they are dead steady, I have never had one fail­ure. In the UK you can get a 97 oc­tane fuel from BP and Shell so I use that, but it will run quite OK on nor­mal un­leaded.” The Tonkin Tor­nado is pow­ered by a 500cc Mol­nar Manx en­gine, with over­all gear­ing re­duced to pro­duce a top speed of 115mph. The first ex­am­ple in Aus­tralia went to Roger Klobe at Hamilton, but there is now a sec­ond bike at Beech­worth and Steve says he has two more solid en­quiries, both also from Vic­to­ria. Roger’s has done 7000 miles and all he’s had on it is a cou­ple of back tyres and chains. He rides his fairly hard too, he uses it. It started first kick this morn­ing. There is an­other one at Beech­worth, and the bike that I am build­ing now is go­ing to Ballarat and I have two other en­quiries from Vic­to­ria. Roger has clocked up 7,000 miles on his, with noth­ing more re­quired than a cou­ple of rear tyres and chains. It’s a first-kick starter too. Roger takes up the story:

“About eight years ago I pur­chased a 1954 al­loy en­gine Feath­erbed Nor­ton In­ter­na­tional, think­ing, ‘How good am I?’ I now own the clos­est thing to a road-go­ing Manx ever produced. Af­ter an­other two years of fet­tling, it is a very re­li­able and fun bike to ride and has since com­pleted sev­eral thou­sand miles at var­i­ous ral­lies around Aus­tralia. But like all 60-yearold mo­tor­cy­cles there is al­ways the nig­gling in the back of your mind, will I make it home? Know­ing my love of such beasts, a friend sent me a one page ar­ti­cle about a chap in the UK who was pro­duc­ing a gen­uine, built for road use, Manx – the Tonkin Tor­nado. I fool­ishly re­sponded to the email ad­dress and it all started. That was about five years ago. I made con­tact with Steve Tonkin to find out the tech­ni­cal spec­i­fi­ca­tions of this piece of mag­i­cal fan­tasy. “It turns out that Steve com­mis­sioned Andy Mol­nar to pro­duce 20 mod­i­fied Manx cranks to ac­com­mo­date reg­u­lar Bri­tish type al­ter­na­tors, this be­ing the main stum­bling block when peo­ple have tried to cre­ate such ma­chines. The en­gine is stan­dard race type Mol­nar Manx ex­cept it has 10:1 com­pres­sion to run 98 oc­tane petrol. A 36 mm MK2 Amal carb and self­gen­er­at­ing elec­tronic BTH mag­neto en­sure usual first kick starts and when hot it has a lazy idle at 1,200 revs. The de­light­ful gear­box is a 5 speed by Mick Hem­mings. There al­ways seems to be the right ra­tio avail­able as cir­cum­stances re­quire. Gear­ing is set at 4,500rpm (max torque) at 70mph so she never sees a hill and you can work out top speed at 7,000rpm. Fuel econ­omy is 65 miles per gal­lon cruis­ing and down to 25 in anger. When dyno tuned, torque is flat from 4,500rpm and power of 38hp at the back wheel was still ris­ing at 6,500rpm. “The frame is made of the best ma­te­ri­als by Mol­nar (made from CDS in­stead of the orig­i­nal Reynolds 531 tub­ing), with bil­let yokes and Manx Road­holder forks. Front brake is a 4ls Fon­tana with su­perb pro­gres­sion and fan­tas­tic feel. Rear hub is a Tri­umph con­i­cal made to look like a Manx, with 18” al­loy rims. The 5 gal­lon al­loy fuel tank is cus­tom made, as is the catch tank, oil tank and seat to com­plete the pack­age. The pri­mary belt drive and NEB clutch are housed in a cus­tom made al­loy Com­mando type pri­mary case and cover which is ac­tu­ally 50mm longer than the orig­i­nal. I have now owned the Tor­nado (#4 built) for three years (#8 and #13 are also com­ing to Aus­tralia) and com­pleted over 7,000 miles, the long­est trip be­ing ap­prox­i­mately 600km in one day. Sur­pris­ingly the ride is quite soft given the su­perb han­dling, when you en­counter the bumps on our shock­ing ru­ral Vic­to­rian roads it doesn’t mat­ter how far you’re cranked over, the Tor­nado al­ways stays on line. I seem to have in­ad­ver­tently ended up as Steve’s world R&D of­fi­cer. There are not many small things that have had to be reme­died along the way. Steve has been most forth­com­ing with any backup or bits re­quired.

“A big bonus out of all this is that Steve and I have be­come good friends. He came over to a Nor­ton Club Rally that I ran two years ago and he re­turned the hospitalit­y last year when I at­tended the Clas­sic TT and Good­wood Re­vival. You def­i­nitely meet all the right peo­ple when a past TT win­ner is mak­ing the in­tro­duc­tions at these sort of events.”

Steve Tonkin at­tended the 2017 Is­land Clas­sic at Phillip Is­land and spent many hours chat­ting to peo­ple about his cre­ations. Roger’s Tor­nado was parked in the garage area all week­end and was the sub­ject of hun­dreds of snap­shots and videos. Steve says the price de­pends on the spec­i­fi­ca­tion. With a Manx 4ls front brake and the higher of the two spec­i­fi­ca­tions for the Manx front fork, they are 43,000 UK pounds. Roger’s bike has a Tri­umph rear wheel but they are now sup­plied with a Mol­nar-made Manx rear and a Fon­tana 210mm front brake and in this spec­i­fi­ca­tion the price is 40,000 UK pounds.

ABOVE LEFT Fon­tana 210mm dou­ble sided twin-lead­ing shoe front brake is the best drum in the busi­ness. ABOVE BTH mag­neto has orig­i­nal ap­pear­ance but mod­ern in­ter­nals. LEFT One happy owner!

Smiths-replica in­stru­ments look the part. Rear hub on Roger’s bike is a BSA/Tri­umph con­i­cal. Amal 36mm Mk2 carb will give way to Mikuni on future pro­duc­tion. No pas­sen­gers here. Steve Tonkin with his cre­ation. Mick Hem­mings sup­plies the Quaife de­sign...

Bri­tish-made NJB rear shocks have been de­vel­oped from the orig­i­nal Gir­ling de­sign.

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