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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.

Want to run a PWK carb version instead? (CLICK HERE)

Stage 2 (EFI) builds on our proven 172cc Stage 1 foundation and replaces the carburetor entirely with a full auto-tune fuel injection system. No jetting, no warm-up stumbling, and no elevation adjustments. The ECU automatically corrects fueling for temperature, load, and altitude — you just key on and ride. Expect clean throttle response, smooth idle, and steady power everywhere in the RPM range.

The Details

This is the same reliable, cool-running 172cc setup — the largest big-bore you can run without case mods — now paired with self-adjusting EFI for hands-free fueling control.

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) with feed & return lines
  • EFI Wiring Harness (simple 3-wire connection)
  • UNI pod air filter (pre-installed)

EFI Magneto / Charging System Options:

  • 11-Pole Magneto — Works on most stock charging systems
  • 18-Pole Magneto — Higher output for builders running lights, pumps, or accessories

Both magnetos function the same with EFI — choose based on how much electrical load your build will run.

Choose Your Top-End Package:

Full ProBld (Forged) — best for performance + longevity:

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

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

  • Cast piston (strong, but not abuse-rated like forged)
  • Rings installed by you
  • NCY big-valve head (28 mm / 23 mm)
  • NCY cam for strong low-end torque
  • Clocking flange + NGK spark plug included

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

Important Things to Note

You must verify you have a QMJ157 engine.
(CLICK HERE) to learn how to confirm.

EFI requires a fuel return — drill-in nipple included, or use EFI Crown Gas Cap: (CLICK HERE)

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