sdgmoto.com.au
1981 Suzuki GSX750
THE Grumpy Old Men are a former road-racing sidecar team from the NSW Central Coast who, when the time came to hang up the leathers, found themselves with a shed full of fabricating tools, a lifetime of metalworking skills and all missing the camaraderie of sharing a common purpose. So they set about fixing all that by forming a collective to restore or modify bikes for themselves and their mates. “We built a Honda Bol D’Or for a mate that we showed at Throttle Roll last year,” Scott Gittoes says of a Matchless G50-styled cafe racer that has since featured in a bunch of magazines and blogs. “We sat down afterwards and thought, we need something for next year. Pete said he still had that basket-case Suzuki so we decided we’d get onto that.” Pete is Peter Steele, who with Dave Ashe had formed the nucleus of Scott’s pit crew back in the day. The Suzuki was a disassembled pile of parts, what was once a 1981 GSX750 owned by Scott’s former sidecar passenger, Brian, who had pulled it to bits with a view to building something not a million miles from what you see here. Brian had already sourced the GSX-R1100 front end and Hayabusa rear but had hit a brick wall, so he sold it as an unfinished project to Pete for not much. Brian had the vision, as Scott puts it, it was now up to them to realise it. The motor was dispatched to Danny Dest for a rebuild while the team concentrated on mating the late-model suspension to the early-girl chassis. “Danny’s a very good engine builder,” Scott says. The bottom end was treated to new bearings while the top end scored new valves and seats, a new camchain and first-oversize pistons and rings. The engine is the same as fitted to the first 750 Katana so Pete and Scott report there were no problems sourcing parts on the ether, including all new seals, gaskets and a kit to refurbish the original carburettors. Ignition is a stock electronic CDI unit, fed by an SSB lithium battery hidden in the seat cowl, while Delkevic four-into-one headers from the UK dump into a Tri-Y muffler for that classic four-cylinder note. To see these guys in action is a hoot. They swear like troopers, laugh a lot, call each other names, drink lots of beer when tools are downed and solve problems as a team. “We’re alway arguing with each other,” Scott says. “Grumpy Old Men had nothing on us. But we get the result.” The front end was relatively straightforward. Scott and his wife Danielle run SDG Moto, a custom motorcycle accessories and clothing brand with a locally-manufactured bespoke line which includes CNC-machined billet top triple clamps. The original GSX-R1100 bottom clamp is retained. Front wheel is from an R1 Yamaha, including the brake rotors, although the calipers have been upgraded to four-piston Brembos mounted on custom brackets and fed by HEL braided lines. Scott also machined spacers to mate the Yamaha wheel to the Suzuki forks. “A lot of the Japanese stuff is very similar,” Scott says. “It’s all pretty easy to do when you’ve got it sitting in front of you.” The dusty end is where it gets more interesting. The seat subframe was cut off just ahead of the top mounts for the twin shocks, with the remaining section forward of that braced and gusseted to take a custom top mount for the single Hayabusa shock unit, which is adjustable for both compression and rebound damping, as well as spring preload. The bottom of the shock is attached to a progressive rising-rate linkage, which pivots off a point below the swingarm spindle (in this case, an existing chassis cross-brace gusseted for strength). Scott then replaced the fixed-length rods which hook up the linkage to the swingarm itself with rose-jointed adjustable rods which he can use to fine-tune both ride height and the progressive rate of the suspension action. Amazingly, matching the Hayabusa’s swingarm pivot to the GSX frame was by comparison a piece of cake; the spindle diameters are identical so it required only a couple of spacers to make it all work. Next job was to make a path for the drive chain, which Scott achieved by fitting an offset drive sprocket with more teeth than standard and by sectioning the left side of the swingarm with 10mm alloy plate. The rear sprocket also increased in size to keep the final drive ratio as close to stock as possible. Rear wheel is from a GSX-R1100, including the rotor gripped by a twin-piston Brembo caliper. The final frame mod was fabricating a new rear seat loop to fit under a bevel-drive SS solo seat unit. This section was braced and gusseted to contain all the electrics under the hump. The fuel tank is stock. Paint is by Jap Sports Finishers in Berkeley Vale in a fetching shade of BSA Bantam olive green with cream. “I picked the colours,” Scott says, with a view to giving it the look of an older bike. “The others pooh-poohed me but I stuck to my guns. People love it, it’s the first thing they mention when they see the bike.” Shack-O Pinstriping, also in Berkeley Vale, hand-painted in 3D the early Suzuki tank logo with gold leaf and then added pinstripes to the tank and seat in burgundy. A chopped Hayabusa front guard is fitted, while the back end gets by without one. Getting exactly the right distressed black leather for the seat was a chore; Pete ended up buying a whole hide just to get the look he wanted! “We’ve got enough left over for another 70 seats!” Scott says. For accessories, the team ransacked the SDG Moto parts bin, which in addition to the Tri-Y muffler includes Joker Machine risers for the stock Suzuki handlebars, an SDG-branded Speedhut GPS speedo, Pingel fuel tap and filter, and a small Joker Machine rear-view mirror. Rear-sets are also Joker Machine with mounting brackets and linkages fabricated in-house. The control levers, blinkers and taillight were sourced elsewhere, while the headlight is from Dime City Cycles. The Suzuki brake master cylinder is retained. Tyres are a matched pair of Bridgestone Battlax Hypersports. If the bike looks brand new, it’s because it mostly is. “Nearly every nut and bolt has been replaced with stainless-steel Allen heads, all the washers too,” Scott says. The Suzuki was finished on schedule and made its debut at Throttle Roll 2016 where it attracted a lot of attention. “I’m over the moon with the finished result,” Pete says. “The boys have done a stirling job, it way exceeds my expectations.” With no time for idle hands, the Grumpy Old Men are already into their next project — a hot rod Triumph America — after which they’ll tackle a rigid SOHC Honda 750 chopper for Scott. They’re already arguing over the colour. THE FIRST GSX SUZUKI was all about two-strokes until the release of the DOHC eight-valve GS750 four in 1976 and later the GS1000. These were replaced in 1980 with the 16-valve TSCC (Twin Swirl Combustion Chamber) GSX750 and GSX1100, the engines of which also powered Katanas from the following year. Just as the Honda CB750F lived in the shadow of the almost identical 900 Bol d’Or, so did the GSX750 in the shadow of the monster 1100, only more so. They were physically the same size, the 1100 maybe an ounce heavier but significantly more powerful at just under 100hp. By comparison, the 750 made just under 80hp (up 9hp on the GS) but was still a handful at 229kg dry or more than 250kg wet. Contemporary road testers likened it to an underpowered 1100, some describing it as bland and Two Wheels christening it The Pig (mostly on account of its pork), which was probably bit harsh. On the plus side, the new GSX engines proved to be very strong, the 1100 in particular a long-time choice of drag racers on account of its bulletproof bottom end. A bigger fuel tank, up five litres to 24 litres (as on the feature bike), was introduced in 1981 and adjustable rear shocks in 1982. Under-piston oil cooling was added in 1983 but by 1984 the model was looking old and not getting any lighter. Suzuki responded with the giant-killing 100hp 179kg GSX-R750 slabby in 1985, heralding the modern sportsbike era and consigning the original air-cooled GSX to history. Retro Specs ENGINE Air-cooled inline four-stroke four; chain-driven DOHC, four valves per cylinder; 67 x 53mm for 747cc; 4 x 32mm Mikuni carburettors; 9.6:1 comp; electronic CDI; Delkevic headers, Tri-Y muffler; wet clutch to five-speed gearbox and chain final drive; 79hp @ 9200rpm (stock) CHASSIS Twin-loop tubular-steel main chassis; custom seat loop and rear shock mounts; GSX handlebar on Joker Machine risers; Joker Machine rear-sets UP FRONT GSX-R1100 USD forks and bottom clamp; SDG billet top clamp; Yamaha R1 17in wheel and rotors; Brembo four-spot calipers with HEL braided lines; 120/70-17 Bridgestone Battlax Hypersport tyre DOWN BACK Modified Suzuki Hayabusa swingarm, shock and rising-rate linkage; Suzuki GSX-R1100 wheel and rotor; twin-piston Brembo caliper; 180/55-17 Bridgestone Battlax Hypersport tyre BODYWORK GSX tank; SS Ducati solo seat trimmed in leather; chopped Hayabusa front mudguard; Dime City Cycles headlight; SDG/Speedhut GPS speedo; paint by Jap Sports Finishers; graphics by Shack-O Pinstriping SPECIAL THANKS Peter Leven for help with the electrics WEBSITE www.sdgmoto.com.au SUMMARY Old meets new in a timeless blend of 50s, 80s and modern styles Article reproduced with the permission of Geoff Seddon, Editor, Retro Bike Magazine Photos by Jeremy Hudson Photography [ngg src=galleries ids=6 display=basic_thumbnail]