Electric Dirt Bike Build Ep.3 | Installing Motor, Custom Sprockets & Building 2 Stage Transmission

We are officially in the thick of the e-dirt bike build! In Episode 3, the bike starts looking like a real machine. I’m tackling the motor installation, custom part fabrication, and a deep dive into the 2-stage jackshaft transmission logic.

In this episode:

Fabrication & Prep: Creating motor mounting plate and battery supports from 1/8" pickled steel.

The Powerplant: Installing the 10kW motor from Golden Motor and explaining the bolt-on mounting strategy for future upgrades.

Precision CNC Work: Using the Makera Carvera Air and Genmitsu ProVer XL to machine custom axle blocks, battery brackets, keyways and sprockets.

The Transmission: Building a custom 2-stage chain driven jackshaft system. I break down why I chose the 6.6:1 gear ratio and a 520 O-ring chain over a belt for this trail machine.

Weight Check: We’re currently sitting at ~150lbs. Can we keep the final build under 200lbs?

Featured in this video:
Motor: Golden Motor HPM-10KW 72V

Website: https://goldenmotor.bike/JAMESBIGGAR (use code JAMESBIGGAR to get 5% off)

Battery Cells: Molicel 21700 P42A

Huge thanks to The Electric Bike Laboratory for the Molicel 21700 P42A cells and copper bus bars. If you’re building your own pack, check them out at the link below.

Electric Bike Laboratory - Molicel P42A & More!
https://www.electricbikelab.ca/

What’s Next?
Stay tuned for the next video in just a few days, where I do a deep dive into how I design and DIY my own sprockets. After that, we start the 72V 50Ah battery build for this bike!

Missed the earlier episodes? Watch the full playlist here:

https://www.youtube.com/playlist?list=PLdO3Wk-XPC_BQ7GYUZqXf11yAac_USfDP

Specs:

Motor: Golden Motor HPM 10kW continuous / 20kWp dual stator PMSM
Controller: EZ-B72800 sinewave, 72V, 800A phase / 400A battery current
Transmission: 2-stage, 6.6:1 gear ratio, ~330Nm torque at the wheel
Battery: 72V lithium pack (planned ~4kWh, 100km range)
Suspension: 790mm adjustable forks + 330mm rear shock w/ progressive linkage
Wheels: 19” front & 18" rear, ~12” ground clearance
Target curb weight: ~190 lbs
Top speed: ~75 km/h

Time stamps:
00:00 - Intro
00:30 - Making motor mounts
03:04 - Pickling steel
03:52 - Installing the motor
04:40 - Making foot peg brackets
06:13 - Making kickstand bracket
08:08 - Installing foot pegs & kickstand
09:36 - Machining axle blocks
13:22 - Installing chassis gussets
14:16 - Machining battery brackets
15:58 - Motor curves & gear ratio explained
17:18 - Machining jackshaft & sprockets
18:52 - Installing 2 stage transmission
24:39 - Weigh-in
25:28 - Battery component preview
25:51 - Cell pre-balance wall preview

#ElectricDirtBike #EVBuild #Fabrication #MotorcycleBuild #GoldenMotor #CustomChassis #LaserWelding #DIYMotorcycle #ElectricMotorcycle #MetalFabrication #3DPrinting #TubeBending #Welding #CNC

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