ProBld GY6 Full Auto Tune EFI System

Tired of your GY6 engine struggling to start or run smoothly? This is where EFI changes everything. Instead of constantly messing with jets, needles, and air screws, this **ProBld GY6 Full Auto-Tune EFI System** does the thinking for you.

This is the latest version of our EFI kit — over **6 years in the making**. It’s designed to work on any scooter or bike running a **GY6 QMJ157 150cc or 171cc engine**, regardless of which harness you’re using, as long as you have the right stator setup.

Why EFI instead of a carb?
A carb is totally analog. You physically swap jets and move needles to chase the correct air/fuel ratio. Once you finally nail it, the weather, altitude, or humidity changes… and you’re back to guessing. Carbs are 1800s tech — literally (invented in 1888).

EFI is digital. Our system uses:
• An **atmospheric pressure sensor** (for altitude & weather changes)
• A **throttle position sensor** (TPS)
• A **narrowband O2 sensor** (exhaust feedback)
to constantly adjust fueling in real-time so your engine stays happy no matter where or when you ride.

How it integrates with your GY6:
• Works with any GY6 QMJ157 150cc or 171cc engine
• Compatible with pretty much any wiring harness (Ruckus swap harnesses, Chinese harnesses, etc.)
• Requires an **11, 12, or 18 pole stator** 8-pole stators will NOT work with this EFI system.

Need a stator upgrade?
• 8-pole → 11-pole kit: CLICK HERE
• Upgrade to 18-pole system: CLICK HERE

Simple wiring:
The EFI harness itself is very straightforward:
• +12V keyed power
• Pickup signal (blue wire from your stator / pickup coil)
• Ground/remaining harness connections handled via the included EFI wiring harness

This EFI system doesn’t just control fuel — it also takes over the **ignition system**. Your old CDI box and coil are no longer used. The CDI logic is built into the EFI ECU, and a dedicated EFI ignition coil is included.

Fuel system & return line options:
EFI requires a **return fuel line** back to the tank. You have two ways to set this up:

1. **EFI Gas Cap (recommended)** — Replace your old cap with our EFI cap that has a built-in return port.
2. **Drill-in Tank Nipple (included “freebie”)** — Drill your tank and install the supplied return nipple with a Viton o-ring. (Drilling the tank is at your own risk.)

The kit also includes a **high-pressure fuel pump (42 psi)** so you won’t reuse the old vacuum or low-pressure pump.

Special note for Honda Ruckus ECU users:
If you’re running the **stock Ruckus ECU** or our **Rolling Wrench GY6 wiring harness**, you’ll also need a **fuel pump simulator** to keep the ECU happy:
CLICK HERE This tricks the factory ECU into thinking a fuel pump is still connected.

Current displacement support:
• Fully supported: **150cc & 171cc GY6 QMJ157**
• In development: 180cc, 190cc, 205cc, 232cc tunes (not ready yet)

Kit Includes:

• Full CNC ProBld EFI intake manifold (anodized gold) with Viton o-ring & hardware
• Installed fuel injector
• Installed throttle body with integrated ECU
• Installed UNI pod air filter
• High-pressure fuel line
• Low-pressure return fuel line
• EFI wiring harness (3-wire install)
• Return fuel nipple with Viton o-ring (not included if you purchase an EFI gas cap)
• EFI fuel pump (42 psi) + mounting clamp
• EFI magneto (you select the correct stator size in the dropdown)
• Narrowband O2 sensor
• Weld-in O2 bung for your exhaust

Once installed, the system self-adjusts for cold starts, altitude changes, and temperature swings — so you can spend less time tuning and more time ripping.

• Fits GY6 QMJ157 engines only — 150cc & 171cc supported at this time.
• Requires an **11, 12, or 18 pole stator** — 8-pole stators will not work.
• You must have or create a **fuel return line** back to the tank (EFI gas cap or drilled tank nipple).
• EFI system replaces your **carb, CDI, and ignition coil** — do not reuse the old components.
• You’ll be swapping to the included **EFI magneto** — make sure you select the correct stator size in the product dropdown so we send the right part.
• If using a stock Ruckus ECU or a Rolling Wrench GY6 harness, you’ll need the **fuel pump simulator** to avoid ECU errors.
• Larger displacement tunes (180/190/205/232) are still in development — not ready out of the box yet.

Installation is very straightforward for anyone comfortable with basic wiring and engine work. If you’re unsure what stator you have or whether your setup is compatible, reach out — we can help you confirm before you order.