Silent Assassin: Empulse R E-Scrambler

In 2012, Brammo introduced the Empulse R, an electric motorcycle with fully adjustable suspension, carbon-fiber bodywork, and a water-cooled engine boasting 54 bhp and 61 lb-ft of torque. Rare for an e-bike, the Empulse came with a six-speed gearbox instead of a direct-drive setup and also a tachometer — conventional interfaces that helped riders feel more at home on this all-but-silent machine, though performance was the goal. Said Wired magazine:

“This thing doesn’t just serve as practical, fun transportation; it uses the benefits of electric propulsion to achieve real performance benefits over internal-combustion-engine sportbikes…”

Brammo had enlisted well-known AMA racer Eric Bostrom as a development rider, which showed in the bike’s impressive handling, and reviewers claimed the bike rivaled other naked middleweights like the Ninja 650, Suzuki SV650, and Triumph Street Triple.

In 2015, Polaris acquired Brammo’s electric motorcycle business, rebadging the bike as the Victory Empulse TT. Unfortunately, the bike was only available for a short time, as Polaris closed down the Victory brand in 2017.

Enter the Max and Erica Droog of the USA’s Droog Moto, who build some of the meanest post-apocalyptic brawlers and city sleds on the planet — machines would warm the stony heart of Mad Max himself. Recently, a client brought them an Empulse R to build. It was a new challenge for the couple, working with and around the massive array of battery packs and wiring harnesses, but they managed to create the brutal electric scrambler you see here. Below, we get the full story on this “Silent Assassin.”

Electric Scrambler: In the Builder’s Words

We were recently presented with an opportunity to build a client’s electric bike. When we received a bit more info regarding what the power output was and some of the features, we knew it would make for a killer scrambler style bike. Built to tackle service roads and get off the everyday pavement, we had a big hurdle ahead of us to overcome. Budget and build design were some of the many obstacles that were a variable but it still was built into a great off-road capable machine.

Power is provided by a 10.2 kWh lithium-ion battery pack using nickel cobalt manganese (NMC) chemistry, with an on-board J1772, level II charging system recharging the battery in just 3.5 hours and every ten minutes of charge time providing five miles (8 km) of range. Complete level I charging takes eight hours. The Scrambler features a drivetrain consisting of a 40 kW water-cooled permanent magnet AC motor generating 63 Nm of torque coupled to an IET 6-speed gearbox with multi-plate, hydraulic activated wet clutch. The shiftable transmission is great for the riding experience. It is a bit strange shifting a bike and not really hearing an engine, just the AC motor spinning. It has tons of torque!

Electric bikes obviously don’t have carbs, fuel pumps, injectors, etc… to deal with, just TONS of wiring and components that do all sorts of work to keep this machine moving. That was the first and one of the more major feats to take on. The other aspect of this was the main core of the build. This one in particular is constructed with large batteries that are bolted into a housing and part of the main frame geometry. On top of that is all the other electronic components that need to be in a set place to function properly.

We started by building a faux tank. This is more of a cover to keep the electronics concealed and protected. There is a large vented air inlet on the top front to help keep some of the components cool. It has access on top to the charging port and the ignition key located on the left hand side.

The bike was equipped with a 7” LED headlight fitted into a steel tracker plate paired up with a sleek hand formed front fender. Also fitted to the bike is our 1 1/8” DM fat bar and enduro style grips.

The main frame of the build is quite chunky so keeping up with appearances we built a one piece subframe to hold the new seat along with charging system components. All lighting is LED keeping voltage use low and helping with battery life. Not commonly seen on our builds is a shorty rear fender to keep the tail light clean from debris. Also fitted is a skid plate we fabricated to keep lower vitals protect.

The suspension on the build is great with on-the-go adjustments, perfect for hitting some trail riding and everyday commuting. Built with Marzocchi front forks and a Sachs rear shock. We also beefed up the swing arm with a new rear shock mount aiding in ground clearance and a new HD spring. The Marchesini rims keep the build weight down a bit and then wrapped in aggressive all terrain tires.