Royal Enfield Dirty Purdy by MotoMAX
For their 2026 Busted Knuckles Build Off entry, MotoMAX Perth took the Royal Enfield Shotgun 650 and pushed it closer to the edge of what the platform always hinted at.
Named Dirty Purdy, this build does not try to reinvent the Shotgun. Instead, it takes what was already there and turns it up. The Shotgun 650 arrives with a strong custom-inspired identity from the factory, so MotoMAX chose to lean into that and push it further — lower, longer, louder and more aggressive.
The thinking behind the build goes right back to the original Shotgun concept. That early machine was bold, unconventional and almost extreme in its styling. As with any production motorcycle, some of those more radical design elements had to be toned down along the way to meet compliance and usability requirements. MotoMAX saw an opportunity in that. Their goal was to remove those constraints completely and build a version of the Shotgun that fully embraced that original vision — and in some ways, took it even further.
That intent is obvious the moment you look at the bike.
The defining feature of Dirty Purdy is its exhaust system, and from the outset, that was non-negotiable. MotoMAX knew the bike had to wear a true twin “shotgun” exhaust setup, and that idea became the visual anchor for the whole build. The finished pipes exit high and wide on each side at a 45-degree angle, giving the motorcycle an unmistakable stance and a hard-edged silhouette that immediately sets the tone.
It was during fabrication, working with a local welder, that the name Dirty Purdy came to life. “Purdy” is a nod to the well-known high-end shotgun manufacturer, while “Dirty” speaks to the raw, cut-down, sawn-off feel of the system itself. With no mufflers in place, the result is as unapologetic as it sounds. Loud, direct and impossible to ignore, it is a huge part of the bike’s personality and one of the reasons the name stuck.
The stance was another major focus of the build. MotoMAX wanted the bike to sit lower and longer, bringing it closer to the look and attitude of the original concept machine. To get there, the rear was dropped by approximately 40mm with revised shocks, while the front fork internals were modified with heavier oil to support the bike’s new posture. Comfort was never the priority here. This build is about attitude and presence first, and every decision around the chassis reflects that.
To reinforce that low-slung silhouette, MotoMAX brought the rear guard and seat down as close to the tyre as possible. Achieving that meant adapting a rear guard hanger from the Royal Enfield Goan 350, then pairing it with a custom rear guard and a genuine Royal Enfield accessory seat. It is a neat and purposeful solution that helps clean up the rear of the bike while keeping everything tight and visually cohesive.
One of the more interesting decisions in the build is what MotoMAX chose not to change. On many customs, handlebars are among the first parts to go, but in this case they were left exactly as they were. After trying multiple options, the team found that nothing improved on the stock Shotgun handlebars. They simply worked best for the bike’s overall design, stance and proportion, and keeping them became part of the discipline behind the build.
That same discipline runs through the broader approach to the project. MotoMAX were careful not to fall into the trap of throwing endless budget at the bike just because it was a custom build. The focus instead was on achieving maximum impact with minimal excess. That philosophy shaped not only the parts chosen, but also the finish.
Rather than applying an elaborate paint job, the team stripped the bike back to raw steel, letting the material speak for itself. The only graphic treatment is MotoMAX’s signature piston bolt logo, a detail that has become a hallmark of their builds. It gives Dirty Purdy a rugged, honest finish that feels completely in step with the rest of the motorcycle — mechanical, stripped-back and full of intent.
And then there is the sound.
MotoMAX describes it as every bit as outrageous as the bike looks, and that feels about right. With those high-mounted twin pipes and no mufflers, Dirty Purdy is raw, loud and impossible to ignore. It is the kind of motorcycle that leaves an impression long after it has disappeared from view. The kind of bike that goes through a tunnel and has people turning to each other afterwards saying, “Did you hear that thing?”
That is a big part of what makes this build land so well.
For all its attitude, Dirty Purdy still feels true to Royal Enfield’s wider ethos. It is not about overcomplication. It is not about custom for the sake of custom. It is about taking a platform with strong character and using a clear vision to draw more out of it. It is a build grounded in simplicity, individuality and mechanical honesty, which makes it a natural fit for Busted Knuckles Build Off.
The Shotgun 650 is already a motorcycle that invites riders and builders to make it their own. With Dirty Purdy, MotoMAX has done exactly that — building a version that is rawer, lower, louder and more extreme, while still staying connected to the spirit of the machine it started from.
It is bold. It is stripped back. And it leaves a mark.