172cc Cast Piston Cylinder - Rolling Wrench

Want a solid GY6 power upgrade without spending top-dollar? This 172cc Cast Piston Cylinder is a reliable, budget-friendly drop-in option for the QMJ157 engine. It delivers real seat-of-the-pants gains in acceleration and torque — all while staying daily-ride friendly and easy to install.

The Details

This 61mm (172cc) cast piston big-bore kit is the largest true drop-in upgrade for QMJ157 engines — no boring, no machining, no case work required. If you’re looking for a noticeable bump in power without stretching the budget, this is the go-to setup.

Cast pistons are a good match for everyday scooters, offering smooth operation and an OEM-style ride feel. The piston rings come pre-installed and correctly gapped, making the install clean and beginner-friendly. Bolt it in, fire it up, and enjoy stronger mid-range pull and quicker take-offs.

• Budget-friendly big-bore option
• Pre-installed rings for easy assembly
• Improves acceleration and torque
• Compatible with stock or upgraded heads/cams
• Ideal for daily riding and casual builds

Important Things to Note

• Must be a QMJ157 engine — this will not fit other GY6 variants.
• Best suited for normal daily riding and light-to-moderate upgrades.
• If you have a buggy/go-kart: stud spacing varies between manufacturers.

Not sure which engine you have? Click here to decode your engine.

What's Included

• 61mm Cast Piston Cylinder
• Cast Piston
• Pre-Installed & Pre-Gapped Piston Rings
• Wrist Pin & Circlips
• Base Gasket & Head Gasket

Everything required for installation — no case boring needed.