Classic Bike Guide - Real rides, real riders

It’s a retro Bruce, but not as we know it...

A crisp exhaust note echoes through the subtropical greenery as a delicate little cafe racer attacks a switchback road on an Australian coastal escarpment.

Reverse-cone meggas are the finishing touch to a contemporary custom that harks back to the days of backyard hot rod innovation.

The latest product from Coffs Harbour-based custom house Raider Motorsport, in northern New South Wales, this Japanese special breaks the mould in this genre of retro motorcycles. Rather than being based on Yamaha’s SR series, it delves into Honda’s XB range, in this case a 1988 GB400.

The logic of this is obvious once you start talking to Raider Motorsport principal
Maurice Rissman.

“Our customers come from a totally different angle,” he says. ”They are not traditional motorcyclists but a new group attracted by the style of these customs and the fact that they aren’t the latest, fastest motorcycles around.

“The XB engine has several advantages over the SR. The main one is that it’s electric start, whereas the SR is kick-start, so the Honda is much easier to live with.

“In standard form a typical GB Honda puts out around 40bhp and weighs around 180kg.

Just by cleaning up the ports we can get an easy five more horses. Add this to our chassis work, which saves about 20kg, and you get a motorcycle that will easily cruise at the freeway speed limit and is quite brisk and rewarding to ride on winding roads.”

The Honda is considered by most experts to be more reliable than Yamaha’s SR, which had issues with oil cooling and electrics. Likewise, the Honda is regarded to have superior handling and a more powerful engine in standard form. The single-overhead-cam, dry-sump XB engine has been developed via Honda’s enduro models. Its signature look is the external oil feed pipes and its twin-port head.

While there is an entire subculture devoted to the SR, Honda’s equivalent model hasn’t had this treatment yet.

Soichiro Honda himself had a hand in the creation of the GB range. Although sales didn’t set the world alight, they are still considered a genuine attempt to pay homage to the best of British single-cylinder technology.

Some 25 years on, GB250, 400 and 500 models are coming on to the market via auctions in Japan. As one of Australia’s largest importers of late-model used motorcycles, Raider Motorsports has accumulated a stock of affordable donor bikes.

The firm began modifying SR Yams, creating aManx lookalike, sold for $17,000 (£9000), a fair price for the nearly 200 hours work.

That led to a small run of SR-based specials, before moving to Honda’s XB as donor bikes.

In Australia, good original SRs and GBs can fetch $8000 (£5000). Raider Motorsports sells its versions for about double this after spending up to 150 hours remanufacturing them.

Strip away the slightly slabby styling of the original and you can see a good basic package crying out for minimal bodywork and more delicate controls and instruments.

“The difference between us and other similar retro-bike builders is that we don’t rely totally on aftermarket suppliers but we build and modify everything ourselves,” says Maurice.

“For this project we spent quite a few hours at a motorcycle wreckers finding a seat and steel tank that would suit the long, narrow shape we wanted.”

That was the start of a lengthy process that saw the bottom of the petrol tank modified to clear the engine’s cam cover and the rear subframe cut to accommodate the seat. A strong bracket was welded between the rear shock mounts to improve handling during fast cornering.

The minimalist look created its own set of design challenges and many hours were spent on details that would pay dividends at the end of the build.

For example, the sealed battery was mounted sideways on a special platform under the seat. Nearby, the electrics, including the fuse box, were neatly positioned.

Looking at the finished product from the front, nothing is wider than the forks. No better is this shown than in the megaphone exhaust system. The custom-built pipes tuck in tightly to the frame and the megaphone mufflers are parallel to the lower frame rails. This ensures clean styling and good ground clearance but isn’t a five-minute job.

A more conventional process was applied to the engine and rolling chassis.

Wheels and suspension were rebuilt to standard specification and the engine was treated to a leak-down test.

While this showed everything was within factory specs, the head was removed and the valve seats cut and lapped in for peace of mind. The inlet and exhaust ports were cleaned up with the inlet being opened up slightly.

“We’ve decided to keep the engine fairly stock in this instance,” says Maurice. “We’re looking for a practical classic riding experience. Having said that, the minor modifications have given an engine that pulls strongly and has more power in the higher rev range.

“Options for the future involve looking at cam profiles and compression ratios.”
The make-or-break of any custom project are the finishing touches.

A clean look for the front forks involved special brackets for the headlight and speedo.

The charcoal paint scheme extends throughout, including the carburettor. The cheeky ‘flying R’ logo on the tank stands for Raider Retro and it sums up the whole point of the exercise, which is a slightly irreverent take on a modern classic.

Words and photographs by Hamish Cooper