Richard Pollock has been building motorcycles since before Bike EXIF existed. With such a tenure comes a measure of consistency; the man behind the Mule Motorcycles moniker never disappoints.

Although Mule is best known for his impeccable Harley flat trackers, he does just as well with other marques too. His latest project is a 2005 KTM 525 EXC with an erratic backstory and one heck of an attitude.

“It started out as a ‘well used’ trail bike that was street plated,” Mule explains. “I bought it two years ago, with the intention of turning it into my personal motocrosser. Then I got a call from a customer that I had previously built a Harley XR1000 for; he wanted a street supermoto build.”

“I built the bike with tons of new parts—it took at least a year and a half. Once I delivered the bike, he decided he wasn’t all that happy with the supermoto seat height for everyday blastin’ around—so he shipped it back for street tracker redo.”

In stock trim, the KTM 525 EXC is a fire-breathing monster with a laughably low curb weight and enough torque to pull your arms from their sockets. But when Mule first got his hands on this particular one, it was, in his words, “a worn-out rag.” An obsessively comprehensive rebuild was on the cards.

The motor was stripped and put back together with a 566 cc cylinder and piston from Built Motors, oversized head and base gaskets, and a KTM 866 crankshaft (as used in the KTM 790 Duke and 1390 Super Duke R EVO). It was also treated to a five-angle valve job and some minor porting.

Mule also upgraded the carb to a 41 mm Keihin FCR, with a new intake boot to match the larger carb, and a two-piece K&N filter. Next, he fabricated a new two-into-one stainless steel exhaust header, terminating in a refurbished muffler from a newer KTM enduro.

Other new items include the valves, valve adjustment screws, guides, guide seals, cam chain, cam chain adjuster, clutch plates, rocker arms, clutch plates, and more. Every last gasket, seal, o-ring, and bearing was replaced. The 525 also sports new oversized radiators and hoses, and fresh titanium-colored Cerakote on the stator and clutch covers.

Mule binned all of the KTM 525 EXC’s bodywork, before ordering a full set of replacement plastics and a new fuel tank to dress the bike with. The seat is from the KTM Powerparts catalog. The whole kit looks stock-ish, with bold Mule graphics to remind you that it’s not.

Hiding under the new bodywork is a scratch-built wiring loom, complete with a high-output stator, an adjustable voltage regulator, a new coil, and a new plug cap. The battery’s a lightweight Lithium-ion number, helping to shave more weight off the already light EXC.

Up in the cockpit, you’ll find new KTM handlebars, fitted with Renthal grips, a new throttle, a Brembo brake master cylinder, and pared-down switches. A digital dash from Trail Tech sits front and center, just above a Bates-style headlight with LED internals. Tiny LED turn signals and an OEM-style LED taillight complete the set.

Subtler upgrades include braided stainless steel brake lines from Crown Performance, an updated clutch cable, and a thermostatic fan kit. With no plastics to hide the bits that normally lurk near the headlight, Mule took a left-field approach to mounting the ignition barrel and horn.

The KTM’s main frame went unmolested, but the subframe was ditched in favor of an aluminum unit. Everything was stripped and powder-coated, and then put back together with new bearings. A chromoly side stand from Mule’s catalog keeps the bike upright when parked.

The original forks and rear shock are still in play, but they’ve been overhauled and lowered. The billet yokes are from a later model KTM, but the aluminum bracket that holds the headlight, front fender, and brake hose guide is a handmade part. Little bespoke parts and shiny KTM factory bits are peppered all over this 525.

Finally, Mule rebuilt the KTM 525 EXC’s wheels to match his client’s request for a street-ready flat tracker. The hubs and 19” rims are from Warp 9, with Buchanan spokes sitting between them. From the Dunlop DT tires to the rebuilt brake calipers, brake pads, front rotor, chain, sprockets, and chain adjuster bolts, there’s not an inch of this KTM that isn’t factory-fresh.

Mule’s KTM 525 EXC street tracker is a prime example of form following function—and another feather in the cap of one of the scene’s best custom motorcycle builders.

Mule Motorcycles | Instagram | Images by Bart Cepek