EC Wildcat 240RS Racing Engine with Maxima Break-in Oil

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EC Wildcat 240RS Racing Engine

Part Number: WC240RS

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Online Price: $684.99

Phone Order Price:$799.99

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Wildcat 240RS Race-Spec Small Block Engine – High Performance 240cc Minibike & Kart Engine

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Wildcat 240RS Race-Spec Engine

The Wildcat 240RS is a standout small-block engine offering the largest displacement in its class, combined with top-tier factory upgrades. This means you get a high-performance powerhouse without the need for immediate modifications or teardown. Designed to excel across a broad range of applications—from spec kart racing and highly modified racing builds to mild or wild minibikes—the 240RS delivers unparalleled versatility and value. Best of all, we’ve made this performance accessible by keeping the price incredibly competitive. Simply put, you won’t find another engine delivering this level of performance at this price point.

Important Notices:

Dyno-Tuned Before Shipping: Each engine is dyno-tuned using a karting fuel tank with a 1/4" vent and fuel pump. Using stock or certain aftermarket mini bike fuel tanks with venting through the fuel cap or check valves can pressurize the carburetor, causing a rich running condition. This is a venting issue, not a tuning problem. You may need to modify your tank by adding a 1/4" vent fitting open to atmosphere for proper function.
Float Bowl Handling: Engines are run before shipping. Shipment may cause the carburetor float to stick. If rich running persists after resolving tank venting, remove the float bowl, check float movement, and ensure the needle valve operates smoothly.
Engine Mounting Angle: The engine runs best mounted flat or up to an 8° angle. Mounting at a greater angle—due to motor mounts or chassis rake—can cause hesitation or stumble at low speeds.
Exhaust Recommendations: Avoid stock mufflers, screw-on styles, “weenie pipes,” or any exhaust with an ID smaller than .900". Restrictive exhausts cause the engine to run rich and lose performance. Use headers with a minimum .900" ID.

Dyno and Performance Resources

Dyno Comparison Video: Watch here
Dyno Comparison Blog: Read more

Engine Specifications & Highlights:

Displacement: 240.11cc with a 72mm bore and a 59mm stroke crankshaft—the largest small block displacement available, equivalent to Honda’s smallest big block. Think of it as the “427ci LS” of minibike and kart engines.
Cylinder Head: The Wildcat WC946 head features 31mm intake and 25mm exhaust stainless steel valves with billet retainers, offering significantly more flow and durability than typical small block valves. Learn more about the WC946 head here.
Carburetor: The upgraded WC22 26mm slide carburetor is expertly blueprinted and tuned in-house for optimal performance, delivering a clean air-fuel ratio of 12-13:1 on high-octane pump gas (best under 1800 ft elevation). This carb is a proven upgrade over competitors, backed by dyno results.
Camshaft: The included Banzai 265 camshaft is a benchmark for mini bike and kart engine upgrades, designed to clear the 59mm crankshaft without modifications, delivering enhanced power right out of the box.
Flywheel & Ignition: The lightweight cast aluminum flywheel safely handles up to 8500 RPM. Rev limiting is controlled by a 6100 RPM coil (similar to the Ghost 212). For RPMs above 7000, upgrading to a billet rod and high-RPM coil is recommended.
Spark Plug: We’re the first to include a fine-wire iridium spark plug, which improves power by 0.2–0.3 HP by providing a more focused and consistent spark under high cylinder pressure and richer fuel mixtures.
Side Cover: Identical to the Ghost 212, with a convenient top-side oil fill and the option to add a Pressure Control Valve (PCV) for crankcase venting without block or valve cover modifications.
Top Plate & Fuel Pump: Designed for near turnkey installation, the included top plate and fuel pump work seamlessly with the WC22 carburetor, especially when the stock fuel tank is not elevated enough to gravity-feed properly. Elevated tanks may require bypassing the pump.
Soft Grip Pull Rope: A small but quality upgrade—durable, comfortable soft-grip handle instead of cheap plastic.
Break-in Oil: Includes Maxima Racing Break-in Oil. Break-in requires running the engine under load, not free revving, between 3500–5500 RPM for 15–20 minutes (practice sessions work great). After break-in, switch to Maxima Racing RS 0W-20 or 5W-30 for best performance.

Technical Specs:

Specification	Detail
Displacement	72mm Bore x 59mm Stroke = 240.11cc
Cylinder Head	WC946, 18cc chamber, 31/25mm valves, billet retainers
Compression Ratio	~11:1 (Recommended 91+ octane, non-ethanol fuel)
Carburetor	WC22 26mm Slide Carburetor with short matched intake
Camshaft	Banzai 265 Lift on 224 core (no clearance needed)
Ignition Coil	6100 RPM Limited Coil (No internal governor)
Other Features	Reinforced Block, Aluminum Flywheel, Cast Rod, Top Oil Fill, Fuel Pump

Recommended Upgrade Path:

Billet Rod & Non-Rev Limited Coil: Handles RPMs above 6100 and improves ignition timing for increased power. Uses the 8270 billet rod.
Billet Flywheel: The SK201 lightweight billet flywheel features 34° ignition timing and a stronger magnet for enhanced spark and RPM capability.
Head Porting: The WC946’s large valves offer huge potential—porting can significantly boost performance without additional parts.
PWK24 Flat Slide Carburetor: For added performance beyond the WC22 without internal engine mods. Recommended to move to a 28mm flat slide carburetor when increasing camshaft/rocker arm specs.
Advanced Upgrades: At this stage, modify the head for dual valve springs, install bigger cams and ratio rockers, and switch to chromoly pushrods cut to length.

Warranty Disclaimer

Small block engine with ¾" output shaft, similar to GX200, Predator 212, etc. No warranties expressed or implied. Purchase at your own risk.

Frequently Asked Questions (FAQ) — Wildcat 240RS Race-Spec Engine

Q1: What makes the Wildcat 240RS engine unique compared to other small-block engines?

A: The Wildcat 240RS offers the largest displacement in a small block (240cc) with a rare 59mm stroke crankshaft, combined with premium upgrades like the WC946 cylinder head with larger 31mm intake valves, Banzai 265 camshaft, and a fine-wire iridium spark plug. This combination delivers outstanding power and reliability straight from the box, without needing immediate modifications.

Q2: What applications is the Wildcat 240RS best suited for?

A: This engine is perfect for spec kart racing, highly modified racing builds, and minibikes—whether you want a mild or wild setup. Its versatile design makes it a great fit across a wide range of gas-powered small vehicles.

Q3: How is the Wildcat 240RS tuned before shipping?

A: Each engine is dyno-tuned using a karting fuel tank with a 1/4" vent and fuel pump to ensure optimal air-fuel ratio and performance. It’s important to use a compatible fuel tank to avoid carburetor pressurization and tuning issues.

Q4: What should I know about fuel tank compatibility?

A: Stock or certain aftermarket mini bike fuel tanks may vent improperly, pressurizing the carburetor and causing a rich running condition. If you experience tuning issues, consider adding a 1/4" vent fitting that vents directly to the atmosphere.

Q5: What is the recommended spark plug gap for this engine?

A: For optimal performance with the Wildcat 240RS, we recommend setting the spark plug gap between 0.028" and 0.032".

Q6: What exhaust setup should I use?

A: Avoid restrictive mufflers like stock, screw-on, or “weenie pipes.” Use headers with an inner diameter of at least .900" to prevent running rich and ensure peak engine performance.

Q7: Can this engine handle high RPMs?

A: The standard ignition coil limits RPMs to 6100, but by upgrading to a billet rod and a non-rev limited coil, the engine can safely rev beyond 7000 RPM.

Q8: How should I break in my new Wildcat 240RS engine?

A: Use Maxima Racing Break-in Oil included with the engine. Run the engine under load (not free revving) between 3500-5500 RPM for 15-20 minutes, such as during practice sessions. After break-in, switch to Maxima Racing RS 0W-20 or 5W-30 for best ongoing performance.

Q9: What upgrades are recommended for improved performance?

A: Suggested upgrades include the billet rod and high-RPM coil, lightweight billet flywheel, porting the WC946 head, upgrading to a PWK24 flat slide carburetor, and advanced modifications like dual valve springs and chromoly push rods when pushing for maximum power.

Q10: Is there a warranty on the Wildcat 240RS engine?

A: No warranties are expressed or implied. This is a high-performance racing engine sold as-is, so please purchase with that understanding.

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