Nor­ton’s Iso­las­tic twin is one of the great­est Bri­tish bikes. Peter Hat­field looks at it closely – and re­builds one for us

Real Classic - - Contents -

The con­clud­ing episode of a hands-on guide to a nine-month restora­tion project, in which an 850 Iso­las­tic twin re­turns to the road

Spurred on by the suc­cess of re­fur­bish­ing the in­stru­ments and their pods, I thought about paint­ing the side pan­els and the fuel tank – the tin­ware – and won­dered: How hard can it be? I had zero ex­pe­ri­ence of paint­ing any­thing apart from the usual, un­in­ter­est­ing jobs around the house to score Brownie points. It was ob­vi­ous that there were three im­por­tant fac­tors to ob­tain­ing a good fin­ish: prepa­ra­tion, prepa­ra­tion, prepa­ra­tion.

The tin­ware with its var­i­ous dints and dents was duly pre­pared with lots of fine sur­face filler and even more rub­bing down. Let’s face it: this work isn’t par­tic­u­larly in­ter­est­ing. There’s plenty of ad­vice out there, which I ig­nored ex­cept for one truly ex­cel­lent gem: use Klingspoor wet and dry pa­per. When you think you’ve reached a point where the sur­face can­not be im­proved, is to­tally smooth and re­sem­bles a baby’s bot­tom, you come to the first of the in­ter­est­ing jobs: the re­veal coat. I sprayed on this coat of primer, and re­alised why it was called a re­veal coat – it re­vealed many lit­tle flaws. Back to the prepa­ra­tion...

With all the prepa­ra­tion and prim­ing com­pleted, you come to the easy part, which is spray­ing on the top coats. For the main colour I’d cho­sen Mercedes Benz Azu­rite Blue metal­lic, and I like to think it was be­cause it re­sem­bled the orig­i­nal Nor­ton Mid­night Blue. The re­al­ity was that the paint was an ob­so­lete colour, and I picked up six 400ml aerosols at the Som­er­set VMCC au­to­jum­ble for the princely sum of £15 in toto. Or, as Henry Cole is wont to say, for the pricely sum… Would some­one kindly put him right? Re­mem­ber­ing gloss paint­ing in the house, I’d never use a cheap primer/un­der­coat – a high qual­ity un­der­coat al­ways gives a bet­ter fin­ish. As aerosol paint is very thin, I shot two or three coats of sil­ver wheel paint on the tin­ware as an un­der­coat to the thin blue top coat.

Now for the re­ally joy­ous part: spray­ing on the blue top coat. I sprayed on many thin coats, and what I dis­cov­ered was that aerosol

paint­ing was a del­i­cate bal­anc­ing act. Too thin, and the paint takes on a satin fin­ish; too thick, and you’ve messed up, with the risk of runs and sags that need sanding. I sanded. Used wet, the Klingspoor wet and dry pa­per ti­dies up any such in­com­pe­tence. Once sprayed, I was re­ally happy with the fin­ish on the tank and side pan­els, leav­ing only two jobs for me to do: ap­ply­ing the wa­ter-slide trans­fers and pin-strip­ing. A paint shop would be en­trusted with the dan­ger­ous 2K clear coat­ing.

There was no way that my ham-fisted abil­i­ties could deal with wet paint pin-strip­ing. I copped out. Us­ing a few scraps of mask­ing tape to guide an un­steady hand, 1/8” vinyl tape in sil­ver was care­fully ap­plied; easy-peasy. The ‘Nor­ton’ and ‘850 Com­mando’wa­ter-slide trans­fers were ap­plied to the tank and side pan­els re­spec­tively. Th­ese trans­fers came with a dire warn­ing: do not pro­tect with an acrylic based clear coat. I had read this be­fore­hand, and took the pre­cau­tion of buy­ing some vinyl trans­fers at the same time as the blue paint. This turned out to be pre­scient.

Af­ter ring­ing round half a dozen paint shops to have the tanks and side pan­els clear coated in 2K, not one would touch the job. Think­ing ‘Sod it’, and throw­ing cau­tion to the wind, I ap­plied a thin coat of acrylic clear to a side panel. No ad­verse re­ac­tion. Same with the other side panel. Em­bold­ened by this suc­cess, I shot a coat of acrylic clear over the fuel tank, and watched the trans­fers shrivel and wrin­kle in a trice. Oh, cock. (If you’re not a Brit, in­sert your own ex­ple­tive.)

I couldn’t fig­ure out why the two trans­fers should re­act dif­fer­ently. The prob­lem wasn’t go­ing to fix it­self, so I scraped off the dam­aged trans­fers, clear­ing up the mess with the trusty Klingspoor wet and dry pa­per. Now you can see why the vinyl trans­fer pur­chase was as­tute, as vinyl is not af­fected by acrylic. Com­plet­ing the job with many more coats of clear coat, I was cock-a-hoop with the re­sult, even in the knowl­edge that I was go­ing to have to be very care­ful with any fuel spillage, as acrylic isn’t that fuel proof.

Com­pared to the shiny tin­ware, the frame looked very tatty. It had ob­vi­ously been re­painted at some point, badly, and there were patches of white, which I mis­tak­enly took to be primer. Scrap­ing away at this, it turned out to be ox­i­dised paint. Scrap­ing a lit­tle more re­vealed the orig­i­nal frame paint – paint in pretty good con­di­tion. Armed with noth­ing more than a craft knife blade, AKA a Stan­ley blade, I scraped away gen­tly at this crud un­til I lost the will to live. Then I scraped some more. Then I com­mit­ted a heinous crime. I sprayed the frame with the en­gine in place. And with Ham­merite. I blame it on the men­tal scars in­flicted by the scrap­ing, but the frame does ac­tu­ally look quite good, and not just from 10 feet away.

With most restora­tions, there are high points and low points, jobs you dis­like (see above) and jobs you like. I like, no love, do­ing electrics. I never cease to be amazed at the banal ques­tions asked about electrics on in­ter­net fo­rums, such as: what does this blue/ red wire do? The an­swer is to look at the wiring di­a­gram, which is no more dif­fi­cult to read than the Lon­don Un­der­ground map.

I al­ways do electrics from scratch. Lu­cas electrics were never very re­li­able back in the day, and the pass­ing of forty-odd years isn’t go­ing to im­prove mat­ters. On top of this, more mod­ern com­po­nents are avail­able. The first items to go into The Box were the Zener diode and rec­ti­fier, which were never go­ing to work in my pre­ferred neg­a­tive earth setup any­way. The Boyer Brans­den elec­tronic ignition was spared the ig­nominy of The Box, since it still worked just fine, as did the 6V coils. Nearly ev­ery­thing else was given the old heave-ho, and the elec­tri­cal sys­tem was com­pletely rewired. With eight fuses. If that’s piqued your in­ter­est, and you haven’t dozed off, there’ll be a sep­a­rate ar­ti­cle next time cov­er­ing the re­wire. Right, Frank?

Just as the electrics were up­graded, so was the front brake. With the stan­dard 5/8” (16mm) mas­ter cylin­der pis­ton, the front brake ac­tion

is akin to Roger Moore’s act­ing: wooden. Some may raise an eye­brow at my so­lu­tion of a Street Triple mas­ter cylin­der, but its 14mm pis­ton gives the right amount of feel with­out be­ing spongy. When it came to the cal­liper, I couldn’t bear to dump the orig­i­nal Lock­heed unit, as it looks so beau­ti­ful. It was given a com­plete over­haul. A Grimeca may work bet­ter, but it looks, as its name sug­gests, grim. A new front disc to re­place the cor­roded orig­i­nal, and we’re done. Or so I thought. There was some os­cil­la­tion of the front brake lever, which turned out to be both run-out and dish­ing of the disc – one of a bad batch. For­tu­nately, RGM stands by its prod­ucts, and I re­ceived a new disc a lit­tle while later.

Just when you think you’re mak­ing progress, some­thing comes along to bite you in the bum. I’d no­ticed an oil leak, but the oil was red – a sure sign of ATF from the pri­mary drive. It seemed to be com­ing from the join be­tween the in­ner pri­mary case and the crank­case, which was odd, be­cause it had taken a while to leak. Re­mov­ing the pri­mary chain re­vealed the cause. The crankshaft oil seal’s seal­ing qual­i­ties were some­what com­pro­mised by the seal be­ing in two pieces rather than the orig­i­nal maker’s in­tended one. The en­gine had wet-sumped, and en­gine oil had leaked past the to­tally knack­ered seal into the pri­mary, caus­ing it to fill up. The ATF rose to the top of this oil mix, and finally leaked past the nonex­is­tent gas­ket be­tween the in­ner pri­mary cover and crank­case. A new oil seal went on the list.

There are some parts that you can res­cue, and some you just can­not. The rear tail light fair­ing and wheels were in the for­mer cat­e­gory, the seat in the lat­ter. The tail light fair­ing had a chunk taken out of it, but it was easy to fab­ri­cate a new piece, graft it on, and paint the whole af­fair. It looked good.

De­spite look­ing as though I’d need new spokes and wheel rims, the old ones pol­ished up sur­pris­ingly well, so I kept them. The seat, al­though ini­tially look­ing like a can­di­date for restora­tion, was scrap. The killer was the badly dam­aged GRP base. Any­way, hav­ing a Mk3 frame, I had my eyes on a new, lock­able seat by An­dover Nor­ton, and the square pat­terned cover looks su­per.

And this is the best part of any restora­tion: com­plet­ing it by fit­ting the new, shiny parts. Let me say at his point that I love pol­ished stain­less steel. When it came to re­plac­ing the ex­haust sys­tem, no one could touch Ar­mour’s for qual­ity, looks and price. With new stain­less hang­ers and roses from RGM, the new Ar­mour’s ex­haust fit­ted like a dream, and looked like one. The seam­less si­lencers pos­i­tively sparkle in the sun. I can­not see why you’d choose chromium plated si­lencers. Or zinc plated fas­ten­ers. They’re prac­ti­cally cor­rod­ing as you’re putting them on. No, for me it’s Dave Mid­dle­ton’s stain­less steel fas­ten­ers ev­ery time.

The restora­tion had taken nine months, and I was re­ally pleased with the re­sult, all the more so when the bike passed its MoT test first time. Armed with MoT cer­tifi­cate, NOVA, US ti­tle and other sundry pa­per­work, I reg­is­tered the bike with DVLA, and re­ceived an age-re­lated num­ber. I could now look for­ward to rid­ing one of Eng­land’s iconic mo­tor cy­cles dur­ing the sum­mer of 2017.

So, what’s it like to ride? It’s a bit heav­ier than a 650cc Bon­neville, but a lot lighter than a 750cc Tri­dent, and han­dles bet­ter than both of those equally nice bikes. But the best part is that the Com­mando’s 850cc en­gine has a shed-load of torque, and there’s no need for more gears than the four in the box. The US Nor­ton im­porter was right on the money with the sales slo­gan: ‘Whole Lotta Torque about Nor­ton.’ Play on words aside, you don’t want to talk about a Nor­ton – you need to ride one. This is one of life’s bare ne­ces­si­ties. There­fore, I have a bet­ter slo­gan: ‘Go Com­mando.’

Take a set of rusty fork yokes, clean them up and re­paint them. Great re­sult, seen to best ad­van­tage when re­fit­ted to the steer­ing head

New front disc, re­built caliper

Nearly fin­ished!

One frame be­fore paint­ing, and the same frame af­ter paint­ing. It’s not en­tirely usual to paint a frame with the power train in­stalled, but if it works…


And then it’s on with the trans­fers, and on with the clear acrylic top coat. And then off with the trans­fers again, be­cause they re­acted with the clear coat…

Photos by Peter Hat­field

When re­paint­ing a fuel tank, prepa­ra­tion is ev­ery­thing. Even if this in­volves a ter­ri­fy­ing amount of rub­bing down At last: into primer On goes the sil­ver paint

Blue at last, Mercedes Benz Azu­rite Blue to be pre­cise. Time for a trial fit to the frame

Pin-strip­ing. Us­ing tape, not a brush

The tank as it was, com­plete with the dent Re­mov­ing the dent!

Peter Hat­field’s full house. Two twins and a triple, 650, 750 and 850. Best of Bri­tish!

A slightly re­vised view from the pi­lot’s seat

There should also be a gas­ket be­tween the crank­case and the pri­mary chain­case. Here’s one now

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