Electric Off-Road Motorcycle Conversion Kit

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The YZ400A is a prototype electric dirt bike design derived from an existing generation of Yamaha 4-stroke motorcycles. The goal of the project is to create a low cost electrification conversion that can be an alternative to rebuilding a failed engine. The benefits of electric motorcycles are typically offset by their high cost. When cost is able to be reduced, benefits are increased significantly.

Four-stroke off-road motorcycle technology gained huge momentum at the turn of the millennium, but while the suspension and chassis components of these machines remain fully functional the power plants have seen better days. This creates a vast population of machines that can be purchased for very little due to the high cost of refreshing a tired engine.

The YZ400A conversion kit features 4 basic systems; motor, controller or inverter, lithium battery, chassis.

In any electric vehicle project, the lithium battery and managing that battery is key to a successful project. Utilizing cells from a salvaged Chevrolet Volt is by far the most cost effective way to create a battery pack. This conversion uses a 2.4kwh “block” at a cost of roughly $100/kwh. The battery is simply balance charged either on or off of the motorcycle. Batteries can be replaced in as little as 10 seconds making for quick pit stops after 20-50min of riding time!

The motor used is Motenergy ME1003, it is a permanent magnet brushed DC motor that can create the substantial torque and horsepower required to make the machine fun to ride. Efficiency is nearly on par with a brushless counterpart, and brush replacement is an extremely low occurrence item. The high torque and low RPM of this motor allows it to be “direct drive” with a single reduction via chain to the rear tire. This eliminates the need for a clutch and shifter making the machine the ultimate in beginner friendliness.

Throttle control is handled by a Kelly 800A DC motor controller capable of nearly 60hp if more voltage were added to the battery. The standard throttle is replaced with a special potentiometer based throttle assembly and grip.

The initial prototype was completed in early 2017 and has been undergoing testing this year. While there are some welded pieces to the original frame, with a bit more design work this can be a completely bolt-on setup.

Bike Specification:
Original Model/Manufacturer: Yamaha YZ400f, 1999
Top speed (with current gearing): 44mph
Horsepower: 35hp
Weight (ready to ride) 261lbs
Duration: 30-60min (depending largely on duty cycle)
Total Cost of Prototype: $1700 (Initial cost of motorcycle, $400. ~$800 reclaimed in sold engine parts)
MSRP of completed vehicle: $5000 + $500/spare battery
Achievements: 3rd place in +30 class, Extreme Enduro Waterloo, Iowa

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  • ABOUT THE ENTRANT

  • Name:
    Dain Sires
  • Type of entry:
    individual
  • Profession:
    Engineer/Designer
  • Number of times previously entering contest:
    never
  • Dain's favorite design and analysis tools:
    I prefer Autodesk Inventor and Solidworks, although I also use Creo and created my latest designs in Autodesk Fusion 360. Analysis I use ANSYS.
  • Dain's hobbies and activities:
    boating, motorcycles, hot tubbing, Busch Light
  • Dain belongs to these online communities:
    SAE.org, DIYelectriccar, Minibuggy.net
  • Dain is inspired by:
    Creating electric vehicles that are stunning in both aesthetics and performance is what I am passionate about. Also, so that I may "send it" without waking the neighbors!
  • Software used for this entry:
    Autodesk Fusion 360
  • Patent status:
    none