FEATURE – 1979 Yamaha SR500 custom
Words: Mike Ryan Photos: David Barker, Mike Ryan
FOR SALE
There’s a saying that projects are never completed, just abandoned. If you’ve had a project bike yourself, you’ll probably agree. Many of us who start projects, especially custom builds and race bikes, are always looking beyond the horizon and it seems we rarely get there.
Thoughts of ‘If I change this, I can also update that’ or ‘If I can lighten this, I can get an extra tenth a lap’ abound in the creative and ambitious mind, driving projects to go on and on . . . .and on.
Having said all that, the notion of “abandoned” projects can be a little misleading, especially in the case of the bike presented here, which is most certainly finished, but the owner is one of those driven individuals who’s always looking for a little bit more!
Worldwide Favourite
Yamaha’s SR500 was already a classic before it became the go-to bike for literally hundreds of custom builders around the world. From backyard tinkerers to professional companies, it seems everyone embraced the SR500 formula (and that of its smaller SR400 sibling) of a simple, reliable single-cylinder engine, cradle frame and twin shock rear suspension as a base for customisation.
Sure, there were some modern touches added over the SR’s long production run, but later versions appeared little different from the original from 1978 and that timeless UJM look has been a constant throughout.
David Barker is one of the many to have an affection for the SR500, which extends to Yamahas generally, as a TR3 and TD1C formerly occupied the garage. Those two models give away the fact that David’s a keen competitive rider. That extends to clubman-level competition in cars, too, with the likes of a Lotus Elan, Jaguar MkII and Mazda MX-5 amongst his four-wheel toys.
Hailing from Tasmania, David’s blessed with an abundance of good roads in his home state, so his passion for fast cars and bikes could be enjoyed often – at legal speeds, of course!
From Simple to Stunning
When David purchased this 1979-model SR500, it was going to get nothing more than a simple restoration – just to running spec. But remember what we said about projects?
“Initially I purchased the bike to restore. However, other ideas took over,” David laughed.
The history of the bike was unknown, but it was neglected and in need of some care when David spotted it online back in 2015.
“My last bike was a big BMW boxer twin, so I wanted to get back to something lighter and simpler - something I could tinker with, too,” David explained. “My initial idea was just to get it going and enjoy it.”
That soon changed.
What was going to be a resto project soon turned into a custom project. A café racer theme was decided upon, but it would be heavily influenced by David’s background with classic Yamaha racing twins: “I wanted it to look ‘period’ and that determined much of how its appearance evolved.”
That classic café racer style explains the conscious approach to the look of certain mechanical elements, most notably the brakes. It wasn’t all about looks, though.
Performance was another factor driving the project. David decided this machine wasn’t going to be just a show pony – it had to go as fast as it looked.
The frame was de-tabbed and lightened wherever possible, but that competition focus meant some strengthening was required in key areas, too.
Factory parts, like the top fork yoke and swingarm, were replaced with lighter aftermarket alloy items. The fuel tank, front and rear mudguards, headlight brackets and other parts were replaced with lighter alloy equivalents where practical, too. With this approach, David estimated the finished build weighs just 140kg dry - that compares to around 160kg for a ’79 SR500 in stock condition.
Finding the “right” parts to suit this project’s performance and aesthetic goals meant going global, so that Manx-style alloy tank and matching seat unit were sourced from the UK, a Motogadget tacho came from Germany, with other parts found in the US, Italy and even Thailand.
Along with the signature café racer clip-ons, rearset pegs and aftermarket headlight, all that polished alloy tinware is a visual feast, but that big, competition -style front drum brake can’t be ignored either. It’s a reproduction 4-leading shoe unit, in the style of what would have graced a TZ350 racer back in the 1970s, so it fits the ‘period’ look David was aiming for. The rear drum brake came from a Kawasaki triple and is similarly beefed-up compared to what the SR500 wore originally.
Performance Plus - eventually
David’s desire to make his SR500 fast – but not crazy fast – meant the 499cc engine capacity was unchanged, but a number of mods were made. A 10.5:1 high-compression piston and lumpier Tighe cam were fitted, the head was ported and gas flowed, heavy-duty valve springs added and a custom exhaust fitted.
Being pretty handy on the tools and able to fabricate and machine certain parts himself, David also adapted a late model Triumph Bonneville reed valve unit to take the crankcase breather to establish crankcase vacuum. An overflow tank and breather unit to complement this were among many other parts that were scratch built for the project.
The result is that the SR500’s engine now puts out an estimated 40hp – up from 31hp in stock form.
The five-speed gearbox is unchanged, but heavy-duty clutch springs were fitted, while the front suspension has been upgraded with stiffer springs and Ikon shocks have been added in place of the factory units at the rear.
“The first year or so after the bike was completed, I ran it at a couple of track days and historic races to sort it out, where it duly disgraced itself by continually misfiring,” David recalled.
Tearing apart the ignition and electrical system produced no identifiable fault, but a track day at Symmons Plains yielded a solution.
“An old bloke, who knew a lot more about tuning than I did, said to take the standard ignition and alternator off the bike and replace it with a total loss system. In his experience, the standard Yamaha ignition system would not handle the higher performance from a modified motor.”
With no other options and nothing to lose, David sourced and purchased a ‘Pazon’ competition system from New Zealand. The difference was immediate: “It totally transformed the bike.”
Obviously, this system has its disadvantages for regular road use, but David only rides this bike during the day, so the only draw on electrical power comes from the ignition, indicators and brake light. Experience with the Pazon system means a full charge of the compact lithium battery that resides under the seat means the bike gets through the day, be it on the road or track, without any worries.
Following that revelation, other modifications included the fitting of a 41mm Keihin FCR flat slide carby and lightening the flywheel.
Revival Runner
While most of his time on this bike has been enjoyed in his native Tasmania, David has taken this SR500 across Bass Strait to several Victorian events, including SR500 club meets and the Geelong Revival Motoring Festival, where’s he’s competed in the sprints for the past four years and where JUST BIKES first encountered the bike.
On the Geelong event’s unique “curved” quarter-mile course, David regularly runs mid-13-second sprint times, with a best of 13.4 – not bad for a bike from the ‘70s!
Of those Revival sprints, David fondly recalls a wet 2017 session where he outpaced much bigger and much faster bikes in the greasy track conditions.
“The bike ran fastest overall, while much faster bikes struggled with traction - 40 horsepower being relatively easy to handle compared to some trying to put 200hp down to a wet surface.
“I had a grin all over my face for a couple of hours - low power/low weight but good power-to-weight ratio sometimes pays off!”
Road and Race
For all the hard work he’s put into the bike (especially sorting out that misfiring issue) and the time he’s spent enjoying it over the past five years – as well as polishing it! - David’s been contemplating putting his SR500 on the market since late last year.
In its current spec, it’s best suited to track days, sprints and historic racing events, but would be usable as a club bike and weekend fun machine, too. David’s improvements and upgrades have made this a more-than-useful road runner and one that undoubtedly stands out.
It caught JUST BIKES’ jaded eye at last year’s Geelong Revival and we’re sure we’re not alone in admiring the style of this gleaming silver machine. Ten trophies won for ten bike shows entered is proof of that. As much as he enjoys its performance, David says he loves the look of this creation, too. Can you blame him?
So, David may have “finished” this project, but we’re sure the next owner will want to tinker, maybe to drop those sprint times a little further. . .
FOR SALE
David’s ’79 SR500 café care may just be the ideal machine for someone looking for a ready-made custom classic they can enjoy on the road and have fun with on the track.
Recent refurbishment work means the bike is ready for the new owner to enjoy as is. It’s also a proven trophy winner.
The asking price is $12,500 ono and David can assist with shipping from Tasmania for the new owner. Call 0499 718 960 for details.
View the advert online at justbikes.com.au with the ad code JBM5163709.
