Trackmaster by Atom Bomb

Trackmaster motorcycle
Clay Rathburn is one of those annoying ‘renaissance’ types who seem to be good at whatever they turn their hands to. First was a string of traditional Triumph hardtails—including the irresistible Velvet Underground. Then we had the RVA Overland vintage dirt bike, and a Harley Sportster 1200 that was straight out of the 70s. So it must be time for something completely different.

The latest Atom Bomb bike is a classic Triumph Trackmaster, finished in the usual immaculate Atom Bomb style. “The client bought me a rolling Trackmaster frame with a bent up swingarm and clapped-out Betor forks,” says Rathburn. “And, as we discovered later, a hell of a motor in it …”

Trackmaster motorcycle
The ’67 motor is sporting a big-bore Sonny Routt 750 kit, big Kenny Harmon cams, steel H-beam rods, a lightened and balanced crank, and a five-speed conversion. “It was a full-tilt race motor. But the valve guides were loose in the head, the seats were cracked, and half the cylinder studs were pulled out of the cases,” says Rathburn. “So I fixed all the issues and put it together just as it had been. I was reluctant to change anything: it felt like I was working on a piece of history.”

Trackmaster motorcycle
Rathburn did change other things, though. He fabricated an aluminum swingarm, installed custom shocks from Works Performance, and fitted a modified Barnes hub. (“Huge thanks to Richard at Mule Motorcycles, who held my hand and pointed me in the right direction on forks and a few other odds and ends.”)

The front end of this Trackmaster is a mix of Yamaha, Buell, Triumph and Ducati parts. Rims are Excel and the tires are Goodyear DTII dirt trackers.

Trackmaster motorcycle
The bodywork is all aluminum and scratch-built by Rathburn. The tank is a replica of the original fiberglass Trackmaster tanks, and the tail is just what Rathburn thought would look good. “My client wanted the seat pad to extend back a little bit, so I shaped the seat pan to fit, and had it covered in black leather by a local shop.”

The stainless exhaust was built in-house and hooked up to a Supertrapp muffler. The custom bars are also stainless, and like the foot controls and pegs, were built in-house.

Trackmaster motorcycle
This was not an easy build, even for someone with Rathburn’s skills and experience. “I stopped working on it a few times, because it was so frustrating. But at the end of the day I love it, and don’t care how much hassle it was.”

Rathburn didn’t get to ride the Trackmaster much, because the client needed it back. “But it sure felt like it was going to be fun after a little bit of dialing in. It’s got way more brakes than any vintage Triumph I’ve ever ridden … and plenty of power!”

Images by Anthony Hall. Visit the Atom Bomb Custom site for more of Clay Rathburn’s work, or check out our archive of previous Atom Bomb builds here.