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Rolling Wrench

GY6 Stage 2 Engine Package - 172cc - Fuel Injection

GY6 Stage 2 Engine Package - 172cc - Fuel Injection

$1,143.00 USD
$1,143.00 USD
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Shipping calculated at checkout.

Prefer a PWK carb version instead? 👉 Click here!

Want to upgrade to stage 3? 👉  Click here!

Stage 2 EFI takes our proven 172cc big-bore setup and replaces the carb completely with a full auto-tune fuel injection system. No jetting, no elevation guesswork, no cold-start stumble — the ECU constantly adjusts fueling so you just key on and ride.

  • 🔥 Full 172cc big-bore + EFI combo
  • 🤖 Auto-tune fueling (no jets to swap)
  • 💨 Stronger pull + cleaner throttle everywhere

The Details ⚙️

This kit builds on the same cool-running 172cc Stage 1 foundation — the largest displacement you can run without case boring — and adds a self-correcting EFI system on top.

EFI System Includes:

  • Throttle body with integrated ECU + injector
  • O₂ sensor + weld-in bung
  • Atmospheric pressure + throttle position sensors
  • High-pressure fuel pump (~42 psi)
  • EFI wiring harness (simple 3-wire connection)
  • UNI pod air filter (pre-installed)

Charging / Magneto Options:

  • 11-pole magneto — perfect for most riders
  • 18-pole magneto — higher output for builds with big electrical load

Top-End Package Choices:

Full ProBld (Forged) — strongest + coolest running:

  • 4032 forged piston
  • Rings pre-measured and installed
  • ProBld big-valve head (28 mm / 23 mm)
  • ProBld performance camshaft
  • 5-axis CNC clocking flange
  • NGK spark plug + all needed hardware

Full Rolling Wrench (Cast) — value-minded daily setup, rings installed:

  • Cast piston
  • Rings pre-measured and installed
  • ProBld big-valve head (28 mm / 23 mm)
  • ProBld camshaft tuned for torque
  • Clocking flange + NGK spark plug included

Full NCY (Cast) — value-minded daily setup:

  • Cast piston
  • Rings installed by you
  • NCY big-valve head (28 mm / 23 mm)
  • NCY camshaft tuned for torque
  • Clocking flange + NGK spark plug included

Already running Stage 1? This is the plug-and-play upgrade that unlocks the full potential of your build.

What's Included 📦

  • Complete 172cc top-end package (ProBld or NCY — your choice)
  • EFI throttle body with ECU + injector
  • O₂ sensor + bung
  • High-pressure fuel pump setup
  • EFI wiring harness
  • UNI pod filter
  • Magneto/charging option (per your selection)
  • All required hardware and fittings

Fitment 🔍

  • QMJ157 GY6 engines only (no QMB / QMI)
  • Honda Ruckus GY6 swap builds
  • Maddog / stretched GY6 scooters
  • Most 150–232cc GY6 scoots + buggies using QMJ157

Engine code is stamped near the center stand pivot — confirm QMJ157 before ordering.

Important Things to Note 🚨

  • Verify QMJ157 engine code before purchasing. (How to check)
  • EFI requires a fuel return — drill-in nipple included or use EFI Crown Gas Cap.
  • High-accessory builds should choose the 18-pole magneto for more power output.

Need help choosing ProBld vs NCY or configuring the EFI? We’re here to help 👍

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