Harley-Davidson XG750R Dirt Tracker Grows New Muscle

Harley-Davidson’s 104-year history of factory support of the uniquely American sport of dirt-track racing will continue in 2018 with a developed version of the Street 750-based experimental XG750R, which first raced during 2016.

The mighty air-cooled XR750, winner of uncounted races and championships since its introduction in 1972, is now officially retired. The three-rider factory team will consist of Sammy Halbert, Brandon Robinson, and Jarod Vanderkooi.

I spoke by phone with Scott Beck, Harley-Davidson’s director of global marketing. “We’ve put together a long-term motorsports package that includes American Flat Track, NHRA drag racing, and hooligan dirt track,” he said.

“When we got into this and really committed, we were seeing dirt track through the lens of a production-based vehicle. But then we were faced with a commitment decision: Would we rather win or be production based?

“In the unending science project that is racing, with the production-based engine we were more limited. We had a lot of power, but what we learned in that year was we needed [chassis] hook-up.”

Beck noted that developing a racebike in public isn’t easy. I thought of the US space program’s early and very public failures. After some hiccups, NASA made moon landings look almost routine.

For Harley-Davidson, racing is an investment in tradition and in the future; tradition because you can’t switch 104 years in dirt track on and off, and the future because people need to know that important things don’t change.

“There’s a connection there that we need to maintain with our riders and fans,” Beck said.

Therefore, new more reliable and higher-performing DOHC heads have been prepared. Gone are the eight highlighted faux cooling fins on each cylinder. Purpose-built racing heads take their place.

Beck said, “Our new DOHC is driven by our durability requirement.” He made clear that the engine uses production cases and other specs.

DOHC gives an engine’s valve train the low-mass “agility” to reliably follow the abrupt high-lift cam profiles that dirt-track engines need to combine acceleration and top speed.

I asked Beck if Harley will sell these machines to the public. “That’s the intent,” he replied, “once we get a package that makes sense for the riders and dealers.”

This is the dawn of a new age of intensive factory-versus-factory dirt-track racing.

Smartphones Turn Innocent Bystanders Into Spies

During 2017, Harley-Davidson replaced the original coolant radiator, tucked up under the steering head, with dual side radiators, each attached to a frame downtube. This provided a shorter wheelbase by allowing the front wheel at full bump to be moved closer to the engine.

It also moved the radiators out of the “wind shadow” and dirt blast of the front wheel, potentially improving cooling. The oil cooler is central but mounted rearward to allow maximum freedom to pull the front wheel back.

Look how close the wheels are to each other. When you need better hookup, you roll the rear wheel closer to the engine, making it easier for acceleration to transfer weight to the rear, where it can become strong early drive off the corner. Has this been done? I can’t tell for sure, but the wheelbase looks shorter than before.

Every human activity has a rumor stream. In this case, I hear four chassis have been built and tested this year. No surprise, the rider in the photo is Brandon Robinson, now Harley-Davidson’s most veteran factory racer.