You have the mo.unit blue in your hand, and your motorcycle is (more or less) ready to receive it—but where do you start? That’s exactly what we’re going to figure out now.
This is Part 4 of our comprehensive mo.unit blue installation series. In Part 1, we covered the complete motogadget shopping list and project overview. In Part 2, we prepared the wiring harness and created the wiring diagram. In Part 3, we learned the basic techniques for connecting motorcycle wires. Now it’s time to get down to business: the motorcycle control unit is going into the bike.
This post is based on the fourth installment of our motogadget installation series on YouTube:
What We'll Cover in Part 4
- Bench test of the mo.unit blue, so you can fully understand how it works before installing it on your bike
- Review the wiring diagram after we've removed everything unnecessary
- Install the mo.unit blue and connect the positive battery terminal and ground
- Install the mo.lock NFC as an ignition lock
- Connect the 12V switched ignition and starter relay
- Starting a Motorcycle
The Benchmark Test: How the mo.unit blue Really Works
Before we even touch the motorcycle, we need to understand what we're building here. The entire system in four parts:
- The battery— supplies power to the mo.unit blue
- The mo.lock NFC – tells the unit when to turn on and off
- Input signals – we use ground-controlled switches to send input signals to the mo.unit (blink left, blink right, start, etc.)
- Output Power – As soon as the mo.unit knows what to do (thanks to your input signal), it sends power through the output side to the intended destination.
The most important thing about the mo.switchinputs: No 12V voltage flows through them. They simply close a circuit to ground—much like a continuity tester works. The mo.unit handles the power. The switch just says “go.” That’s what makes this system so much more reliable than old-fashioned switches, through which full voltage flows.
Pro Tip: Practice this on your workbench first. Once you see how it works with a few cables in hand, the whole system suddenly makes sense—and then installing it on the bike is much easier. To test the outputs, connect a 12V incandescent bulb between the output and ground.
The Wiring Diagram: What's Left
Now that we've streamlined the wiring harness in the second part of this series, here's what remains:
Keep:
- Alternator, Regulator/Rectifier, Stator
- Ignition System and Ignition Coil(s)
- Starter Motor and Relay
- Oil pressure switch, idle switch
Removed and replaced with mo.unit blue:
- Original wiring harness (controls, relays, switches, dashboard—the latter may optionally be reused)
- Headlight relay
- Turn signal relay
- Original ignition switch (can optionally be reused)
- Fuse Box
As previously discussed: The mo.unit does not replace the charging or ignition system.
A feature unique to BMW
To ensure that the alternator charges properly on BMW 2V models (R45, R60, R65, R70, R80, R90, R100), the resistance of the original charging indicator light is essential. If this indicator light is missing, a corresponding resistor is required. This resistor must be connected from the IGNITION output to the regulator using the blue wire.
Golden Rule: Do your research on your specific motorcycle. There’s almost always some quirk that isn’t covered in any video.
Installing the mo.unit blue
For this phase of assembly, the mo.unit blue is screwed onto a steel plate that is tack-welded to the frame. It’s not pretty, but it’ll do for now. The final assembly will feature a neatly welded, powder-coated plate—but at this point, the goal is simply to get everything up and running. It’s important to ensure that the mo.unit isn’t sitting flat, as this can cause stress that may lead to a malfunction.
A few things that are important, no matter how you install them:
- The mounting plate should be conductive and securely welded (or screwed) to the frame so that it acts as a ground
- When powder coating, leave the threads exposed (for ground connection)
- For steel, use grease if necessary
- Check the clearance between the tank and the seat before deciding on a position
- The ground screws on the mo.unit pass through the plate—so a solid metal mount means a solid ground connection
Connect the power supply
Cable specifications from the mo.unit manual:
- Plus (BAT): minimum cross-sectional area of 6 mm² (the Ultimate Builder Kit includes an 8-gauge / ~8 mm² fused cable—slightly above specification, which is great)
- Gauge: 1.5 mm² cross-sectional area (approximately 14 gauge)
Important: Do not install the fuse until everything is connected and you are ready to test the system. A live, fused cable that comes into contact with bare metal will cause a short circuit—resulting in intense sparks, a risk of burns, and possible damage to the mo.unit or other components.
First, connect the positive terminal to the BAT connector (threaded, blind hole—use the small screw that comes with the unit, and apply medium-strength threadlocker during final assembly). The ground connection is made via the mounting plate screws—but leave the nut loose for now, because there are additional ground wires to be connected.
Install mo.lock NFC
There are three cables:
- Black → Ground
- Red → Positive (Permanent Positive)
- Brown → LOCK input on the mo.unit blue (this is your switched 12V)
That's it. When you hold the NFC tag over the lock, the mo.unit turns on. Hold it over the lock again, and it turns off. The motorcycle now has a keyless ignition with no moving parts.
A Hot Cable
Okay, we said that all inputs are ground-controlled—which is mostly true, with one exception: the brown wire from the mo.lock NFC to the lock input. This ensures that the mo.unit also works with original ignition locks that supply a switched 12V voltage. Just connect the brown wire—after that, it’s back to ground-controlled inputs.
Wiring the Ignition and Starter
Two remaining connections to fully integrate the mo.unit blue:
Positive Ignition
The IGNITION output is activated when the mo.unit is turned on and provides positive ignition voltage to the ignition system and the ignition coils. The motorcycle is now ready to be started electrically.
Starter Relay
The mo.unit has two START outputs. On this BMW, both are connected to a single terminal on the starter relay via a dual-plug/single-jack flat-plug adapter. One cable per output; both go to the same relay terminal. This is just so the mo.unit can supply enough power without breaking a sweat.
The maximum current of 30A is important here. Therefore, the original starter relay—or, in the case of BMWs, at least the solenoid—must remain installed. This is one of the most critical aspects of the wiring. If mistakes are made here, it can quickly lead to a wire fire.
Pro Tip: There's a slight built-in delay before the starter motor engages. Don't panic if it doesn't start right away. This delay is intentional—it prevents accidental starts.
First Launch
With just a few connections to the mo.unit blue—Plus, ground, mo.lock, ignition, and two start outputs—the system is "complete."
Insert the fuse. Place the NFC tag on the lock. Green light.
Make sure both START cables are securely connected to the relay or solenoid switch.
It's working.
Before you do that, you should know how to turn it off:
- Hold the NFC tag up to it again—this turns the device off
- Remove the 40 A fuse – this cuts off the power supply
- Have a fire extinguisher ready and open the garage door
Check the charging system
Once the engine is running at about 3,000–4,000 rpm, use the multimeter to measure the battery voltage. You should see 13+ volts. If it stays at 12.6 V or lower, check the connections at the regulator/rectifier. Your motorcycle’s service manual specifies the exact RPM range at which charging begins. What we’re testing here is whether the connection from the charging system to the battery is intact. If the battery isn’t charging at higher RPMs, we’ve overlooked something.
What happens next
Part 5 continues with the handlebars. Both versions of the mo.switch—the pre-wired LED models and the standard versions that you wire yourself—are installed and connected to the mo.unit inputs.
In the meantime: Tidy up the wiring. Once the mo.unit is in the right position, finish welding the mount. Route the existing cables neatly—everything down here should be organized before we continue working on the handlebars.
- Jacob Baldry, for motogadget
