Electric motocross bikes are rapidly changing the off-road riding landscape. While manufacturers like Stark VARG and Flux Primo are grabbing headlines with their new models, the early departure of Alta Motors still leaves many wondering when established brands like Honda, Yamaha, and KTM will fully commit to the electric revolution in full-size dirt bikes.
In the midst of this anticipation for groundbreaking electric models, it’s easy to forget the decades of refinement poured into existing motocross chassis by leading engineers and racers. These proven platforms are perfect candidates for electric conversions. Fortunately, companies are emerging to fill this gap, creating electric conversion kits that seamlessly integrate with some of the most respected motocross bikes ever produced.
One such standout is the Yamaha XE4 Electric Dirt Bike, developed by Xtreme Electric MX (XEMX). Having followed several successful electric conversions, the XE4 Yamaha from XEMX has particularly caught our attention. Our interest intensified after witnessing JoJo Toole’s impressive performance on this bike at the 2022 ECR eMoto Race during the Red Bull TKO event.
Jojo Toole competes on a Yamaha XE4 e-motocross bike at the 2022 Red Bull TKO eMoto race.
Decoding the XEMX Yamaha XE4 Electric Dirt Bike Specs
XEMX offers two conversion kits: the XE2 (air-cooled) and the XE4 (liquid-cooled). The XE4 is designed as a bolt-on kit compatible with Yamaha 250 and 450 YZF and YZFX models. Specifically, it fits 250 chassis from 2014-2019 and 450 chassis from 2014-2018.
The liquid-cooled XE4 system leverages the stock YZF radiators, incorporating a small 12V pump to circulate Engine Ice coolant. Liquid cooling is crucial for maintaining optimal motor temperature, enhancing the XE4’s efficiency and performance during demanding rides. A standout feature of the XE4 is its proprietary fast-change battery swap system, touted as the quickest on the market, enabling battery changes in under 10 seconds.
Our test bike was built around a 2016 Yamaha YZ250F chassis. XEMX typically uses a 12T front and 52T rear sprocket combination, sometimes opting for a 12T-54T setup. Components like sprockets, plastics, suspension, and grips remain stock Yamaha parts, with front sprockets borrowed from a stock YZF450.
Currently, XEMX is rigorously testing various controllers to pinpoint the best overall performance. Controllers under evaluation include the Curtis 1236SE, Votol EM-260S, EBMX X-9000, Fardriver, Kelly, and the Curtis clone, A5. Each controller is subjected to racing conditions to determine the optimal choice for the XE4. Our test bike was equipped with the Curtis 1236SE controller, rated at 450 amps at 72 volts.
XEMX batteries are rated at 72V nominal with a 600 Amp max output, providing a total capacity of 4.3kWh. Being custom-built, these batteries offer flexibility, allowing XEMX to adjust cell type and quantity to meet specific customer requirements. The proprietary fast-change battery swap technology utilizes a modified aerospace connector, delivering 600 amps per terminal. The battery compartment cleverly reuses the Yamaha YZF gas cap lid, resulting in a clean and efficient design that facilitates battery swaps in less than 10 seconds.
The XE4 offers three fully programmable ride modes, along with reverse and auto regen braking. Lever regen braking is also an option. An innovative and unique feature is the optional motor sound system with a speaker, adding an auditory dimension to the electric riding experience.
The XEMX Yamaha XE4 is currently a custom order e-motocross bike, with kits planned for sale after beta testing concludes. Cost breakdowns for the kits are detailed below.
Riding the Electric Revolution: The Yamaha XE4 Experience
While we’ve previously tested the Stark VARG and Alta Redshift, our team frequently rides the KTM Freeride EXC and smaller modified electric dirt bikes like the SurRon Lightbee X. The XEMX Yamaha XE4 delivers a remarkable riding experience. The Yamaha YZF chassis has long been celebrated for its reliability, largely attributed to its unique reverse motor design that delivers class-leading horsepower in the pro MX scene.
Although the stock motor is replaced by the electric powertrain in this conversion, the original design allows XEMX to effectively utilize the space for their motor and battery system. The Yamaha chassis is renowned for its stability and confidence-inspiring handling across challenging terrain. The sought-after KYB SSS suspension comes standard on Yamaha YZF bikes, further enhancing the ride quality.
Riding the XEMX Yamaha XE4 validates the reputation of the Yamaha YZF chassis for stability and superior suspension. The bike feels exceptionally planted, a notable improvement compared to lighter electric dirt bikes under 150 pounds that often struggle in rough, sandy whoop sections common in Florida. It genuinely feels like riding a Yamaha YZF250F, but with a potent electric powertrain – a significant advantage.
If there’s any minor critique of the YZF chassis, it’s a slight trade-off of front-end steering agility for enhanced stability. It’s often favored by riders who “steer with the rear” and prioritize stability over the razor-sharp turning of bikes like KTM, Suzuki, or Honda. However, these are minor nuances, and adjustments can be made to fine-tune the turning characteristics and front-end feel of the YZF chassis.
During our Yamaha XE4 electric dirt bike video testing, we encountered a minor issue. The bike occasionally faulted when hitting sand whoops aggressively at full throttle. Mark from XEMX clarified that a slight misalignment between the sensor and magnet in the motor was causing intermittent shut-offs. This is a known issue in new motors, and XEMX has since resolved it by 99%, attributing the remaining instances to older style connectors. This issue will be fully resolved before the kits are available for sale.
During field testing, Mark from XEMX adjusted the power output, reducing it by up to 20%. This means we tested the bike at only 80% of its potential power. The controller used in our test was rated for 450 Amps, while the batteries are capable of delivering 600 Amps. This indicates substantial untapped power potential within this platform.
XEMX Yamaha XE4 Electric Dirt Bike Pricing Details
XEMX is preparing to launch kit sales, initially focusing on custom billet motors (made to order) and component parts. With their complete A kit and a prepped rolling frame, assembly can be completed in a single day. A Yamaha 250 YZF or FX (2014-2019) or 450 YZF (2014-2018) rolling frame is required for the conversion.
These motors feature full ceramic bearings and a carbon-sleeved rotor, finished in black (Cerakoting or powder coating is available at an extra cost).
BILLET 6061 ALUMINUM MOTOR ALONE: $3,500.
XE4 ALL BILLET AXIAL FLUX MOTOR WITH CARBON FIBER SLEEVED ROTOR, LIQUID COOLED, CERAMIC BEARING, 2.08 TO 1 GEAR REDUCTION. MAX RATING OF 58 HP. @ 600 AMPS NOMINAL 38 HP.
COMPLETE MOTOR A KIT: $6,995.
XE4 BILLET MOTOR AND KIT, INCLUDING:
#1 COMPLETELY BUILT BATTERY TRAY, BATTERY SIDE BRACKETS, BUSS BARS, AND PHASE WIRES.
#2 BRACKETS (FRONT, MID, AND TWO REAR SEAT BRACKETS), CARBON FIBER AIR BOX COVER, SEVEN PIVOT POINT HINGE, HALL THROTTLE, WATER PUMP, MAIN CONTACTOR, DC TO DC CONVERTER, 12T FRONT SPROCKET, CARBON FIBER AND MID SEAT PAD.
#3 CURTIS 1236SE-6571 PRE-PROGRAMMED CONTROLLER AND COMPLETE WIRING HARNESS, POWER PANEL, MODE, AND ON/OFF SWITCHES.
QUICK SWAP BATTERIES SOLD SEPARATELY FROM THE KIT: $3,295.
INR 25R SAMSUNG (400) 18650 CELL BATTERY 500 AMP PEAK AT 84V 4KW, 10 MODULES (40 18650 CELLS EACH). MOLICEL P42 and P45 options are also now available.
OPTIONAL CHARGER: $250.
MODEL S2500 BATTERY CHARGER INPUT: 120V AC VOLT, OUTPUT: 84V=10AMP WITH LED DISPLAY AND FINISH CHARGE INDICATOR. (Higher amp/faster charging options will be available).
OPTIONAL PROGRAMMER: $695.
HAND HELD PROGRAMMER FOR THE CURTIS SE1236-6571 CONTROLLER.
OPTIONAL SEAT: $250.
CUSTOM SEAT CONCEPTS SEAT COVER FOR QUICK SWAP BATTERY SYSTEM.
In conclusion, the Yamaha XE4 Electric Dirt Bike conversion kit offers an exciting and innovative approach to electrifying a proven motocross chassis. For riders eager to experience a full-size e-motocross bike, the XE4 presents a compelling option. With its robust electric powertrain and rapid battery swap technology, the XE4 stands out as a meticulously engineered piece of equipment.
While still in beta testing, XEMX is committed to making these conversion kits commercially available. For more information, reach out to Mark Peroni at www.xemx1.com or via email at [email protected].
