Devil with the detail

Oxfordshire-based Viv Cowley is one of those talented bike builders who can create any kind of custom motorcycle – from wild to mild.  He can fabricate a bike from the ground up. He’s not even adverse to using an engine designed for something entirely different, like an airplane, for propulsion. But he’s equally happy taking a stock classic and reworking every last detail to create something that teases the beholder into a game of spot the differences.

And the latter is just what Viv has done with this K2-model Honda CB75. You can see what it is, and it’s not far from stock but the more you look at it, the more detail mods you spot.

Viv’s penchant for building custom bikes was always there. His day job? Well, how about checking out his résumé? He served an apprenticeship as a toolmaker. Went to work for Tom Walkinshaw Racing as a machinist and fabricator. There he spent time Stateside as well as the UK on the Jaguar racing programme TWR ran and ended up as lead mechanic for two years on the XJ220 Jaguar Le Mans effort. He switched to TWR’s F1 programme when they bought the Arrows team, then went freelance working with Redman Bright in F3000 and the Panoz sports car team. 

He switched to two wheels, with Kenny Roberts’ MotoGP team for a year, and in his spare time, began building custom bikes – his first effort being a single-sided swing-arm Ducati – before Ducati built their first production single-sided swing-arm production machine. After KR’s team, he went freelance for four years working on the A1 GP series and one year as a technician on a Bond movie set before establishing his own custom bike building business. 

This Honda is just one in a long line of Viv’s meticulously engineered customs. The starting point was a £1500 K2 stocker in need of TLC. Viv said: “The first thing I did was to get a heads up of the engine condition, not that it was that important, because the motor was well and truly getting the treatment. Once I did that it was time for the big strip down!

“The wheels were stripped. The rear hub was machined to make it look like a fully machined hub, including cross drilling the hole between the spokes to give the ‘race’ look. The front hub was also machined, just kissing all faces.  Then they were sent away to Tony at Hagon. The hubs and rims were painted black then laced with stainless spokes and shod with Continental tyres for an ‘oldy world’ look. On reflection, I should have gone bigger on the rear rim!”

Next was the frame, which needed cleaning up. Viv explained: “The plan was to make the frame more ‘up to date’, so I cut the entire rear loop off, then brought the top shock mounts forward by 30mm to lay the shocks down. I made a new rear loop, incorporating bracketry for rear mudguard mount. The frame side loops which the side panels live on were made considerably smaller to get away from the stock oil tank/side panels. New top rails were joined by a cross tube to stiffen it all back up. The new side loops meant cleaning up the way the frame lower rails came around and back up to the top rail. 

Viv made a new side-stand bracket for the alloy Ducati stand he wanted to use. He also added oil cooler mounts on front of frame just under the steering head to take a CBX750 oil cooler, modified to accept Wiggins fittings. The stock front engine mount was very bulky and ugly so it was replaced with two welded-in M8 inserts to take a machined front motor mount. Pillion footrest mounts were added in rear lower loops. The footrest mounts were shortened to bring them in narrower as they didn’t need to accommodate the exhaust brackets. The rear brake lever position is now on an eccentric cam. The seat release catch is from a Ducati.

Viv fabricated a ton of parts for this bike including: the front and rear stainless mudguards; stainless stays on front mudguard; he modified the headlight shell to accept the Motogadget dash and made the tubular headlight bracket. He made the aluminium oil tank, adding the screw-on cap under the seat, sight level and then rubber mounted the tank. Capacity is slightly more than stock. 

The alloy left hand side panel is also his work, as is the alloy seat base with a slight raise on rear part at request of owner, (to accommodate his lad). The fuel tank has had the sides fluted, a Monza cap fitted and the fuel tap repositioned. Oil lines have Wiggins fittings at both cooler and tank ends. Alloy covers on the outside two carbs to make it look like a stock airbox, but are hiding the K&N filters. There’s also an alloy rear taillight/ indicator/ numberplate mount.

The front-end features all-black Nitron ‘right way up’ forks in a Yamaha R6 bottom yoke, which has been deflashed, and a RedMax CNC top yoke with risers, courtesy of Steve Hillary at RedMax Speedshop in Devon. New front brake caliper brackets were needed to change from the original axial mount calipers to radial mount Brembo’s. “Because of the draught angle of the spokes,” said Viv, “the inside of the calipers are very close to the spokes so I had to produce a new stainless wheel spindle and various spacers to get the wheel to fit in the tight space.”

At the rear end Viv fabricated an aluminium swing arm to same dimensions as stock but with neater rear mounting plate for shocks and spindle/chain adjustment. He also incorporated paddock stand bobbin mounts. Shocks are all black Nitrons. “Something that caught me out was that on the single-cam Honda 750s, the left rear shock has an offset top and lower mount to clear the chain. So, I’ve had to do the same fitting the Nitrons,” said Viv.

The engine has benefitted from a Wiseco 836 kit but there’s much more. “It’s now got a very lightened and balanced crank which has been knife-edged and polished,” said Viv. “The conrods have been balanced end to end and to each other, and shot peened. I gas-flowed the head, then fitted bigger than stock, Kibblewhite valves with smaller stems and vavle guides to suite. I also bored the exhaust stubs to take bigger diameter headers.” 

Viv opted for a Yoshimura Daytona camshaft and fitted a heavy-duty camchain and primary chain. The new clutch, with uprated springs, is hydraulically actuated. Oil fittings have been changed to Wiggins fittings.

The CB750 still runs on CV carbs. “I chose not to go down the usual CR route as the bike is for everyday use and was advised by my pal Rob Wittey, at PDQ, that the CRs can bog down.” Viv fabricated the exhaust system and opted for a Delkevic end-can which he shortened. “The four into one system is a bit like that on a 400/4, with pipes alongside each other to maximise ground clearance,” he said.

“As with most of my builds it was off to Cheltenham, to see Richard Prowse, for the wiring loom,” he added. “Moto Gadget and Kellermann supplied the hardware and we go through the build to establish the best location for components. It’s got Dyna Coils, Dyna ignition, uprated regulator/rectifier. Everything is very high-end spec. “I was also wanting symmetry on the bars when it came to brake and clutch actuation so radial master cylinders it was with Brembo opaque reservoirs. Motone buttons, There’s a Motogadget bar-end mirror on the right-hand side of the bars.” Finally, the paint. Viv said the original orange livery was truly stunning but the fuel tank had been very rusty and proved very difficult to seal. So another tank was found and painted plain black. The matching side panel graphics have the same font type, but now read ‘836 Four’, scaled down to get the proportions right. The seat is leather with red stitching at the owner’s request, and completes what is one impressive looking, and thoroughly modernised custom classic. 

Photos courtesy Viv Cowley