Using one of only two frames of its kind in existence and with an ultrarare swingarm and wheels, Mark Wateridge’s GPz redefines special.
Mark Wateridge could hardly believe his luck. Years of fruitless searching for a P&M chassis had turned up precisely nothing, and as he forlornly shuffled around the Stafford Show back in 2011 he thought he was never going to get the chance to build his dream special. “Then I saw it,” he smiles. “It was a 1984 P&M with a GSX-R750 engine in it, but when I got chatting to the guy selling the bike it became clear that he didn’t really know the finer details of what he had" Papers were promptly signed, money changed hands and over 30 years after he raced against P&Ms at club level, vowing one day to buy one, Mark finally had his own. Project P&M was on.
Well in hindsight, ‘on’ might have been a slightly optimistic word. Wanting to restore the bike to its original racing condition meant ditching the GSX-R motor and replacing it with the GPz750 engine that the frame was designed for – a job Mark thought would be routine. “I had this grand plan that all I’d need to do was take one engine out, modify a few brackets here and there and put the other one in,” he laughs. “I thought I’d do it over the winter and then it’d be ready by spring. No. Anyone who’s ever built a special will tell you it doesn’t work like that.” It certainly doesn’t.
Mark duly entered a protracted four-and-a-half year period of research, discovery and patience, with the engine causing the vast majority of the head-scratching. “It started when I got hold of a GPz750 bottom end from a Uni-Trak model,” explains Mark. “I put it in and the bolts lined up on the rear mounts, but they didn’t quite fit flush to the frame sides. I phoned P&M and explained to Richard Peckett there – the guy who actually built this frame back in 1984 – that I needed some spacers for the rear mounts. “He said, ‘I can’t do that.’ I said, ‘Why not?” He explained that none of his frames had spacers on the rear mounts, which completely threw me.
AND BREATHE...This red device is a two-way breather valve for the fuel tank, allowing excess pressure to vent the tank but also letting in air as the fuel drops.
GOT A LIGHT? Mark wanted the Yamaha FZ750 rear light to fit flush, which took ages. “I had to cut and fibreglass a recess in the seat and make up brackets to fit the Yamaha light.”
It took me quite a while to discover that Kawasaki changed the width of the crankcases between the 1982 and ’85 GPz engines – when the later model went to the monoshock they narrowed the rear mounts on the crankcases. So I had to get an ’82 GPz750 R1 engine – the last twin-shock one which Kawasaki only did for a year. I bought it for £100 on eBay – I probably spent more on petrol driving from West Sussex to Wales and back to pick it up.”
So please tell us that went in OK, Mark? Well, nearly. “Something else I discovered was that because the frame was built for racing, you can’t put the engine in with the cylinder head on – it won’t fit,” he explains. “The head has to be off to get it in. I called Richard at P&M again and he said, ‘Yep – that’s how we designed it.’” In addition to the presence of a helpful individual who’s a goldmine of information (in this case Richard from P&M, who was always on hand to answer any of Mark’s questions), special builds almost always feature a ridiculous bargain that’s been acquired through a combination of luck and timing. In this case it occurred when Mark was ambling aimlessly through the Kempton autojumble a couple of years ago. “I wandered past this tatty stall, and stuffed between all the rubbish was this pair of valves with a bit of masking tape over them that had ‘Kwak 810’ scrawled on it in black pen. I picked them up and thought, ‘This is a Wiseco big-bore kit.’ I asked the guy how much he wanted for them plus the other six valves and the pistons, and he sucked through his teeth and said, ‘£75’. I beat him down to 60.”
With a custom-made exhaust next on the list built by Mark at MHP (“I’ve known him for years from my racing days so I knew he’d do a great job”), Mark set about sorting the bike’s bodywork. It was a bit of a mish-mash– the tank was from P&M, the fairing was from a 1989 GSX-R1100K and the seat unit was a Harris F1 number. All the parts were in decent nick, but they certainly didn’t line up and flow the way you see them now – that was all done by Mark’s fair hands.
"The seat unit needed quite a lot of fettling to look right,” he says, with a knowing smile that indicates hours of garage time was the result. “The rear light was this brick-shaped thing from a Honda CX500 Eurosport that stuck out a mile, so I got one from a 1986 Yamaha FZ750 instead and made it flush. “The fairing was from a GSX-R1100K, but I wanted to modify it quite extensively because it was a full fairing and I was after that ’80s endurance racer look. I had to cut a big chunk out and re-glass a big section of it – the 1100K fairing has two large air ducts on the side, which I wanted to make flush. I also needed to make the angle of the side of the front fairing match the angle of the seat unit, which took a while. It’s a bit OCD, but when I do a bike there’s only one way it’s going to be done – and that’s right. That’s probably why it took me four-and-a-half years...”
All specials are unique but even bearing that in mind, Mark’s is off the scale in terms of rarity. There’s the Saxon Racing ’arm and ally wheels, which Mark confesses he’s never seen come up for sale on eBay or anywhere else, not to mention the frame. “Richard told me that P&M only ever built two cantilever frames for the air-cooled 750, and mine’s one of them,” says Mark. “The other one was their own works racer from 1985, which is now in New Zealand. This is seriously rare stuff, and there’s not another bike like this on the planet – simple as that.”
You’d forgive Mark for needing to pop anti-anxiety pills every time he gets on the bike, but to his massive credit it gets used – he even battled with Big G at the PS trackday at Cadwell. “It’s just the right side of brutal, which is what an air-cooled motor with a bigbore kit and CR carbs should be,” he laughs. “Of course it’s always in the back of my mind that certain parts couldn’t be repaired, but I’ll never just put it in a warm garage and take it out once a year. It was originally designed to be used, and I’ve spent nearly five years making sure I can do exactly that.”
“The exhaust took about a year to get hold of, after I had a couple of false starts with some other companies. But I’d known Mark Hill at MHP since my club racing days and knew he’d do a great job, so I asked him to make it. I wanted to make the bike look sympathetic to its age rather than go for a kicked-up, GP-style exhaust. We liaised, Mark listened to what I wanted, told me what was and wasn’t possible and this was the result. He’s welded the header pipes but you can’t tell – what a great piece of work.”
“The bike’s had an interesting engine history,” laughs Mark. “It had a GSX-R750 motor when I got it, and a GSX-R1100 lump before that. I could see that a previous owner had modified the upper frame rails because the 1100 engine is taller. But the rear engine mounts hadn’t been changed – they were identical between the GSX-R and GPz units. I soon discovered that the same Japanese engineer had designed both engines. The fact that the P&M frame could take an 1100 engine shows just how strong it is.”
The swingarm was on the bike when Mark bought it, and just like the frame, happens to be ultra-rare. “It was made by a company called Saxon Racing in the ’80s; they made frames too, and even built one for Sir Alan Cathcart. It’s a lovely looking thing: the whole swingarm and rear shock linkage compresses the shock at both ends, whereas the original P&M set-up just had a straight, single cantilever monoshock. I’ve no idea if I could get hold of another one of these if I ended up damaging it.”
SPECIFICATION P&M Kawasaki 750
ENGINE 1992 Kawasaki GPz750 R1, air-cooled, dohc, 8v inline-four, Wiseco 810 kit, Keihin CR31mm smoothbore carbs, skimmed and flowed head, bespoke MHP stainless steel 4-2-1 exhaust system, bespoke wiring loom.
CHASSIS 1984 P&M F1 frame, 1989 Suzuki GSX-R1100K forks, brakes, top yoke, switchgear and clocks, Saxon Racing swingarm, rear linkage and aluminium wheels, Tech 2000 rear shock, P&M fuel tank, modified GSX-R1100K fairing, Harris F1 seat unit, 1986 Yamaha FZ750 rear light
THANKS Rob at Mistral Performance (mistralperformance.com), Mark Hill at MHP (mhpexhausts.com), Tony at Cycle Sprays (cyclesprays.com), Ferret at Ferret’s Custom Electrickery for the loom (motorcyclewiring. co.uk), Richard at P&M, wife Jackie
Steven Wilson shows what you can make with a knackered frame, a vintage sewing machine and parts from 14 different bikes
THE SEWING machine says it all. A vintage Singer model bought for £50, it seems a curious object to be talking about in relation to a home-built motorcycle – but then Steven Wilson is a bike builder like few others. He’d bought the sewing machine near the end of the two-year build process on this RD350, having decided that instead of getting someone to reupholster his seat unit he’d just teach himself to sew and do it himself. “I like to learn a new skill whenever I take on a project,” he smiles.
Added to the other self-taught talents that have seen Steven take on his own powdercoating, sand-blasting, zinc-plating, wheel-spoking, wiring loom build and even paintwork, it’s all culminated in a unique machine that started as a lone frame and now incorporates parts from 14 different bikes that span the entire range of the PS era. From a 1973 Kawasaki 750 H2 rear brake cable to a 2000 Suzuki GSX-R1000K1 sidestand, Steven’s aim was simple: “I wanted to include as many different makes and models of bike as I could just for a laugh, to see what finally rolled out of the shed.”
As you can see, what duly emerged from said shed after two very busy years is a special of incredible skill and ingenuity – not that this was some sort of random, aimless build that saw Steve trying different parts until stuff fitted.
“I pictured the finished bike in my head before I started, all the way down to the paintjob I did which was loosely based on the old Gulf Racing colours from the ’60s and ’70s,” he says. “I’ve built lots of specials and it’s easy to get sidetracked – my biggest piece of advice is to have a plan and stick to it. Otherwise the bike will look crap and end up for sale on eBay as an unfinished project.” What certainly did look crap was the manky old RD250 frame Steven started the entire project with – though it didn’t stay that way for long. “It was a twin-shock frame originally, but I braced the headstock, replaced the rear engine mounting to accommodate the LC engine I wanted to go in it and modified the whole thing to make it monoshock,” he shrugs somewhat matter-of-factly. How on earth did you know where to cut, Steven?
“When I was at school I was an apprentice sheet metal worker and I’ve also got access to a workshop – plus I’ve been messing around with bikes for the past 40 years, so you learn a few things. For this build I decided to buy myself a TIG welder and learn how to use it.” Frame duly sorted, it needed a swingarm to go with it – in this case one from an early ’70s Yamaha RD350A that Steven modified from twinshock to monoshock. This, as you might imagine, was not the work of five minutes. “It involved a lot of cutting and welding,” laughs Steven. “I had to bend and form the pipe for the bracing and then weld the shock mounts on, but making sure everything was true was the biggest challenge. It’s got to go down the road straight as well, hasn’t it?”
With the RD350LC engine built completely from scratch using a mixture of 1980-’83 parts Steven sourced from eBay (“It’s all pretty standard as I think LC engines run better the closer to stock they are”), the 1974 RD350A forks were next – complete with springs from an ’82 Yamaha XJ650 which Steven thought would be a bit stronger given the XJ’s weight advantage over the RD. More news skills were soon on the way as Steven watched a few YouTube videos to teach himself how to spoke the rare Borrani rims he also bought on eBay. “When I first put the wheels together they were all over the place, so I really had to work on straightening and balancing them – it probably took half a day to spoke each wheel and nearly a week to true both of them. The sprocket carrier is from an RD350A but the brake plate is from an early Yamaha YDS7 from 1972, because that’s a bike with a right-hand chain drive. The brake plate is actually fitted on my bike upside down – that was just me trying to get another different bike part on there again.”
When it came to the bodywork, the good news was that Steven managed to acquire a tank and seat unit for a 1980 TZ350. The less encouraging news was that more extensive modification was needed to make them fit. “I had to alter the headstock quite a bit,” explains Steven, “because where you pull the tank off there are these little half-moon brackets that the tank rubbers slot into. I actually had to make those myself and weld tank mounts underneath for the rubbers, plus a mount at the back as well.” With additional parts including a 1992 Yamaha FJ1200 clutch mastercylinder, a slave cylinder from a ’92 Kawasaki ZXR750 and a 1988 Yamaha XJ600 brake lever, not to mention Steven’s homemade wiring loom (“I used an RD350 one for reference – I taught myself about electrics too”), it all begs the question: what’s the bike like to ride?
“It’s fun, because I’ve kept everything as short possible,” says Steven. “It’s twitchy but I don’t get scared about damaging it – it’s there to be used. To be honest I enjoy the build as much as the riding. I have friends who make anal nut ’n’ bolt minters, but all you do is buy specific parts and fit them. Where’s the fun in that?” Steven is proof that whether it’s sewing, welding or electrics, learning new stuff can revolutionise the way you build a special.
ENGINE Yamaha RD350LC engine with 1986 Yamaha RD250 crankcases, RD250 YPVS reed cages, 1980 TZ350 exhaust system, front brake and clutch mastercylinder from 1992 Yamaha FJ1200, slave cylinder from 1993 Kawasaki ZXR750, 1973 Kawasaki 750 H2 rear brake cable, homemade wiring loom
CHASSIS Yamaha RD250 frame converted from twin-shock to monoshock, 1974 Yamaha RD350A forks with springs from a 1982 Yamaha XJ650, homemade adjustable preload, Yamaha RD350A swingarm modified from twinshock to monoshock, 18in Borrani wheels with stainless steel spokes, homemade number board, 1980 Yamaha TZ350 fuel tank, seat unit and mudguard, 1999 Yamaha R1 rear shock, 1974 Yamaha RD350A clock, 1989 Kawasaki KR-1S temperature gauge, bespoke rear light, custom paintjob based on Gulf Racing colours, homemade footrests, 1988 Yamaha XJ600 gear lever and rear brake lever, 2000Suzuki GSX-R1000K1 sidestand modified to fit
TIME TO ADJUST
This blue dial is very clever – a homemade preload adjuster. The silver button next to it is a homemade push-button ignition ‘on’ (there’s no key), with an identical looking kill switch on the other side.
SEEING THE LIGHT
“I just bought a piece of ally, shaped it and cut a hole in it, then bought a fog lamp for a car and fitted that before fibgreglassing and painting the whole thing,” says Steven. “Pretty simple really.”
The 1999 Yamaha R1 shock is just one of many parts Steven has made fit. “Originally it was a dry build – I do that with everything on all my bikes to make sure it all works properly.”
Mounted off the frame just below the fuel tank, the 1989 Kawasaki KR-1S temperature gauge shows that not all instruments have to be in the conventional place.
Steven’s decision to put 1982 Yamaha XJ650 springs inside 1974 RD350A forks made things stiffer, but there was no adjustability due to their age. His ingenious solution? “I modified the top nut on the forks and made an adjustable preload on there myself,” he laughs. “It took a bit of working out, but I looked at how standard ones worked and tried to replicate them. The theory was simple but complicated in practice because you’ve got moving parts inside and outside, and you need seals in there as well to stop oil escaping. But I got there in the end.”
Steven bought all the parts for his RD350LC engine off eBay, plus the pair of ’86 RD250 crankcases. “I’d never built an LC engine before but it’s quite straightforward,” says Steven. “They’re fairly basic and there’s a lot of information around about them. I got the crankcases pretty early on in the project so that when I was doing the monoshock conversion, I put the engine mount in at the back in order that the crankcases would drop in.”
Given that the original TZ was a racing bike it didn’t have a rear light – not that this little triviality deterred Steven from fitting one. Getting hold of a generic rear light, he simply fitted it courtesy of some cutting and fibreglassing. “I made the two aluminium thumb-turn nuts underneath them as well,” adds Steven. “It means everything on the bike is quick-release – I can now strip the tank and seat unit off the bike without the need for spanners if necessary.”
REAR WHEEL EXHAUST
“The rims are by Italian company Borrani who’ve made wheels for decades,” explains Steven. “These are genuine old school racing rims that old TZs used to run on, which I bought on eBay. I phoned Borrani once I’d got them and the guy there said they were from either 1968 or ’69. I used hubs from an RD350A knowing that they’d fit the swingarm, and then joined them to the rims by doing my own spoking. The exhausts are another item from a 1980 TZ350 which bolted straight on after I’d made up some rear brackets.”
Steve Bowyer’s Suzuki special is a clever match of old and new,
brought together with a serious dollop of military ingenuity
I just can't leave it alone. I’ve had so many comments from people saying, ‘That’s perfect – stop.’ And I agree with them... but then a few weeks later I’m thinking, ‘Actually, that’s not quite right.’ Or I’ll be at a bike meet and I’ll see something nice or clever and think, ‘Now that I like...’”
Steve Bowyer, an inveterate fiddler, is talking about his Suzuki GS1157 – at least that’s what we’re calling it, for want of a better name. Because Steve’s bike is part GS750, part 1200 Bandit, part GSX1400, part Fireblade – and a very large part of his own handiwork as well.
Steve, 55, is an armourer for the army by trade. “Basically I fix weapons,” he laughs. “And I just like doing stuff with my hands – I always have. If I can make it myself, I will: 20mm alloy plate, chop it up, file it, get someone else to weld it – because that’s one thing I’ve never found the time to learn properly – then put it together in my shed. Everything on the GS has been made by me, whether it’s a bracket, a plate or a holder. I’m not one of those people who just chucks money at something and gets someone else to build it. That’s not you – it’s your wallet.” Steve’s journey to his current GS started with a smaller GS, the 550, in the late ’70s. “It was back when no one modified bikes at street level,” he says. “You couldn’t just walk into a shop or go on the internet. The only stuff you could get was full race-spec kit, so me being me decided to do just that - a pair of Dymag wheels, 29mm smoothbores, oil-cooler kit, braided hoses, paint job... I just lavished everything on it. And then it got nicked. The police recovered the frame and engine cases when they busted a Birmingham bike gang for drugs; my 550 still had the steering lock on, they’d just stripped it.”
The Falklands conflict and general life would soon intervene in Steve’s two-wheeled career, although he managed to fit in a couple of GSX-R750s and a super-modified Hornet 900. But his affair with the current GS began two-and-a-half years ago.
“I always wanted a GS again,” he smiles, “so I thought I’d build a kind of homage to it – except with modern running gear so it’d look retro but handle and go as if you bought it in a dealership today.
“The frame came first – imported from America via eBay. Then I just started to accumulate other bits. I’d saved up a bit of money so I bought most of what I needed at once; I sat on eBay for two weeks finding the tank, seat and bodywork. Then I acquired the 1200 Bandit engine from a crashed bike – I knew people had put them in GS750 frames before, with a bit of fiddling.” Exactly what kind of fiddling? “I had to slightly stretch the frame... I widened it by about 5mm at the back to get the chain run to line up.”
So when you say ‘stretch’... “Literally, yes. I put a hydraulic ram in between the frame tubes and pushed them apart. You can’t do it by a lot; 5mm is about the limit. Then it was all about repositioning the engine mounting plates. The front pair are the same – you just make new plates – but the side ones had to be modified with new inserts. It wasn’t too bad; the big work was getting the GSX1400 swingarm to fit. I didn’t want to take much metal off the frame mounting points so it was a little bit here, a little bit there off either the swingarm or the frame, just to get it in.
“Once I’d got the engine and swingarm lined up, it was a case of fitting everything else,” adds Steve, completely understating the difficulty of the job. “I bought the loom, CDI and electrics from America. There seem to have been a lot of GSs over there. Parts are scarce here – and if you do find them they’re going for big cash.”
The hardest things to find are decent tanks. “This is the fifth one I’ve had,” says Steve, pointing at his bike. “It took that many to get one that was usable. The rest were like Swiss cheese. The worst thing was when I found a perfect tank – the English seller, based in America, normally used his own couriers but this time he used eBay’s new international shipping service. So the tank got to Delaware airport and they said, ‘We’re not shipping this, it’s not been certified clean...’ So eBay crushed the tank and gave us both our money back. Me and the seller were completely gutted.”
Steve squints at his GS special, glinting in the sunlight. “If you look closely even this tank’s not perfect; there’s a bleb on the side where it’s come through. So I’ve actually got another tank, with a quick-filler twin cap, away being sprayed at the moment. Soon as it’s back this one’s going on my next build; I’m making the same bike but with a 600 Bandit motor, for my girlfriend. We’ll have his ’n’ hers matching GSs – and the paint scheme on both bikes will be the same as the one I had done on my 550 back in the day.” But this one will be simpler, says Steve: “It’ll have a Bandit front-end, right-way-up forks and a Bandit monoshock.”
Yeah, right. Judging by Steve’s record for endless tinkering, what’s the betting the other GS will never truly be finished either?
Registering Steve’s GS hasn’t been easy. “Because the frame came from America, I spent £95 on a Suzuki build certificate. But the DVLA said it was already registered on their database. I phoned up Suzuki who said, ‘Oh, there were two
production lines, one for America and one for the rest of the world, and they used the same numbers.’ So the frame I got was the same number as one registered in the UK (any other country I’d have been okay). I had to get a DVLAnumber
stamped on the headstock.”
OVER THE FRONT-END
Sitting atop a complete 2007 Fireblade front-end is a Translogic race dash on Steve’s own mounting plate. “The dash comes with a loom and only a few wires need connecting: power, revs, rear wheel speed sensor, indicators, brake
lights.” The Renthal Street Low ’bars are held by Triumph risers bolted to the top yoke, then powdercoated as one to look integrated. Switchgear is 1200 Bandit – with a ZX-10R radial mastercylinder and CRG levers.
ENGINE & CARBS
The 1200 Bandit motor is smaller than a GS750’s. “When you fit the Bandit lump you can sit it forwards, but it creates a gap at the back,” says Steve. “So I put it at the back for better chain clearance, but had to fit header extenders
to get the exhaust on.” The Bandit motor has a GSX-R750 clutch, but next is a GSX-R750 head: “It bolts straight on – bigger valves, straighter inlets and hotter cams give 30bhp more. Carbs are Mikuni RS38mm smoothbores. I really like
the sound of open stacks
PICK ’N’ MIX
Forks are 2007 Honda Fireblade with a custom 1mm spacer for the top headstock bearing. 40mm fork top extenders supply the correct ride height. Headlight is Chinese GSX1400, with Steve’s own brackets.
CAUTION: WIDE LOAD
The GS750 frame is widened for the GSX1400 swingarm, with a cross-brace tube added above the pivot (below the side panel) for strengthening. Chinese rearsets are for a Kawasaki ZX-10R.
Subframe and swingarm shock mounts were extended outwards and inwards respectively, then welded in to keep the shocks lined between the narrow GS750 frame and wider GSX1400 swingarm.
ENGINE 2001 Suzuki 1200 Bandit engine, Mikuni RS38mm smoothbores, 2004 GSX-R750 clutch, Akrapovic stainless system with header extenders and cut-back carbon fibre can, 1200 Bandit harness and CDI, 19-row Torques.co.uk oil-cooler and
CHASSIS 1977 Suzuki GS750 frame with bracing, 2001 GSX1400 swingarm, 2007 CBR1000RR forks, yokes and front brakes, Öhlins shocks, 2000 Hayabusa rear wheel, Translogic dash, 2010 Kawasaki ZX-10R front brake mastercylinder, ZX-10R
aftermarket rearsets, 2001 1200 Bandit pillion footrests, Renthal flat ’bars, recovered Guiliari seat, 1977 GS750 tank, panels and tail unit, GSX1400 aftermarket headlight, 1977 GS750 tail light, CRG levers, R&G indicators, Motrax
THANKS Pro Kustom paint (search Facebook), The Dyno Centre, Northallerton (01609 760466), RNR powdercoating, Ripon (01677 470808), Torques. co.uk (oil-cooler and hoses), Halls Autos, Richmond for the welding (01748 810810), Ash for the
frame set-up and fitment, Taff for the machining
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