Description
Stomp YX140 Complete Pit Bike Engine Kit – Z40 Race Cam Fitted (SR140C)
Upgrade your pit bike with the legendary Stomp SR140C YX140 engine – trusted across the UK pit bike scene for its outstanding power, reliability, and value for money. Supplied as a complete, ready-to-install kit, this engine is ideal for both replacements and performance upgrades.
Key Features
- Delivers approx. 16HP at the flywheel
- High-performance Z40 race camshaft with upgraded valve springs
- Big valve head for improved airflow and power
- Durable steel crank with modified flat-top piston
- Smooth 4-speed manual gearbox (N-1-2-3-4)
- Molkt 26mm race carburettor (pre-jetted)
- CNC oil cooler with braided lines for improved cooling
- Stomp Logo side covers
- Includes CDI, ignition coil, kick start & gear shifter
- Supplied with 26mm inlet manifold & air filter
Compatibility
- Fits all Stomp pit bike models
- Suitable for most pit bikes and monkey bikes with Honda-style horizontal engines
Please Note:
This engine does not include charging capability for 6V or 12V electrical systems.
Before You Start
- Correct carburettor setup and jetting are essential to prevent internal damage. Only use recommended specifications.
- Shipping oil must be drained and replaced before first use. High-quality 10W/40 oil is recommended.
Installation & Setup
- Professional installation is strongly advised.
- Ensure the crankcase breather is correctly installed and unobstructed to allow proper ventilation.
Running-In Instructions
- Run the engine at half throttle for the first 2 hours.
- After this period, change the oil and check valve clearances, adjusting if required.
Warranty
- Includes 30-day warranty covering manufacturing defects only.
- Excludes damage caused by incorrect installation, misuse, or racing use.
- Warranty begins from date of purchase.





