GPX 125cc Race Engine, High Comp Piston, Race Cam, Support Lighting

Frequently Asked Questions

• What is the GPX 125cc Race Engine?
  The GPX 125cc is a high-performance crate engine designed for competitive pit bike and dirt bike racing. Unlike standard utility engines, it features a high-compression piston and a dedicated race camshaft to deliver superior power and instantaneous throttle response.
• How does this differ from a standard 125cc engine?
  While a standard engine focuses on basic utility, the GPX Race edition is engineered for the track. It utilizes a race-spec camshaft and a higher compression ratio to increase peak horsepower and extend the rev range. Additionally, it comes equipped with a lighting coil, allowing you to run electronic accessories.
• What are the key technical specifications?
  Engine Type: 4-Stroke, Single Cylinder (2-Valve Head); Displacement: 125cc; Cooling: Oil Cooled; Bore & Stroke: 54mm x 54.5mm; Compression Ratio: 11:1; Transmission: 4-Speed Manual (N-1-2-3-4 pattern); Ignition: Kick Start / CDI; Drive Train: Compatible with #420 chain.
• What kind of power gains should I expect?
  Thanks to the high-compression internals, riders will experience explosive power delivery, faster climbing RPMs, and significantly more torque compared to stock 125cc powerplants.
• Does this engine support lights?
  Yes. The engine includes integrated lighting coil support, making it a plug-and-play option for bikes with headlights or other 12V accessories.
• Will this engine fit my bike?
  This engine is designed for universal fitment across most pit bike and dirt bike frames that accept horizontal 125cc engines. We recommend verifying your frame's mounting points and drivetrain clearance before purchase.
• What is included in the kit?
  The base engine kit typically includes a kick start lever, gear shifter, and intake manifold. Note: Performance upgrades such as the racing coil pack, CDI unit, wiring harness, and oil cooler are sold separately.
• Is installation difficult?
  An engine swap requires intermediate mechanical knowledge. If you are not confident in your ability to timing or seat the engine correctly, we strongly recommend professional installation by a qualified mechanic.
• Does this engine require special fuel or oil?
  To protect the high-compression piston and prevent knocking or detonation, we recommend using premium high-octane fuel. Always use high-quality synthetic motorcycle oil designed for air/oil-cooled engines.
• Are spare parts readily available?
  Yes. As an authorized dealer, DHZ carries a full inventory of replacement parts, including gaskets, piston kits, and ignition components, ensuring your engine stays race-ready.
• Is there a warranty?
  Warranty coverage is provided in accordance with DHZ’s terms and Australian Consumer Law. Please review our specific warranty documentation for race-use components for full details.