How to Choose the Best Carburetor for Go Kart Racing Performance

Choosing the Right Carburetor for Your Go Kart

Installing the right carburetor is crucial to getting peak performance out of your go kart. The carburetor mixes air and fuel and delivers it to the engine. While all carburetors perform this basic function, there are key differences between models that impact horsepower, acceleration, fuel efficiency, and drivability.

Carburetor Types

Two common types of carburetors used on go karts are float bowl carburetors and diaphragm carburetors. Here's an overview of each:

• Float Bowl Carburetors - These feature a float that regulates fuel in the bowl. Fuel enters from the fuel line and raises the float to close the needle valve when the bowl reaches the proper level. The advantage is constant fuel flow. The downside is they may flood if the kart tips or rolls over.

• Diaphragm Carburetors - Instead of a float, these use a flexible diaphragm to control fuel flow. The diaphragm actuates the needle valve to meter fuel. They are less likely to flood and work better for off-road conditions. However, fuel delivery can vary during acceleration and turning.

Key Carburetor Specifications

Here are some key specs to consider when selecting a carburetor:

• Throttle Bore - The inside diameter of the carburetor throat. A larger bore provides greater airflow for more horsepower potential.

• Venturi Size - The narrowest portion of the carburetor interior. The venturi creates air velocity to siphon fuel. Proper sizing prevents restriction.

• Fuel Jetting - The size of the fuel jet openings that regulate flow. Proper jetting prevents running too rich or lean.

• Air Bleeds - Extra air ports that fine tune the air-fuel mixture. Different size bleeds can improve drivability.

Tuning and Adjusting Your Carburetor

Installing the carburetor is only the first step. Tuning and adjusting it for your particular engine and conditions is key to maximizing performance. Here are some tips:

• Adjust the fuel mixture screw in small increments to lean or richen the mixture based on engine response.

• Change fuel jets to fine tune for your altitude and local conditions.

• Modify the throttle stop screw to limit max throttle opening for restricted classes.

• Swapping air bleeds is an easy way to alter air-fuel ratios.

• Upgrade the throttle cable and return springs so the throttle responds crisply.

Choosing a Performance Carburetor

If you're looking to upgrade your existing carburetor, there are several high-performance racing models to consider. Here are some top options:

Mikuni VM Round Slide Carburetors

Mikuni VM carbs are a top choice for kart racing engines like the Honda GX200. The round slide design allows precise fuel control and quick response. Key features include:

• Smooth throttle response

• Available in a range of bore sizes

• Tunable via replaceable fuel jets and air bleeds

• Works well at high rpm

Keihin PWK Air Striker Carburetors

The Keihin PWK is another advanced racing carb optimized for two-cycle kart engines. It uses a flat slide design and lever-actuated power jet for superior acceleration. Benefits include:

• Broad powerband

• Minimal throttle hesitation

• Adjustable air and fuel screws

• Multiple venturi sizes available

Tillotson HS Carburetors

The Tillotson HS is a reasonably priced carb that works well for clone engines. Key features:

• Diaphragm pump fuel delivery

• Self-relieving choke eliminates sticking

• Available in different bore diameters

• Replaceable fuel inlet filter

Installing Your New Carburetor

Once you've selected the ideal carburetor for your application, proper installation is critical. Here are some tips for hassle-free carb mounting:

• Use a new base gasket to ensure an airtight seal

• Align the throttle cable housing stop correctly

• Connect fuel lines securely to prevent leaks

• Attach choke and throttle linkages properly

• Double check tightness of all mounting nuts and bolts

It's also a good idea to connect an oil pressure gauge to monitor engine lubrication when first starting the engine with the new carburetor.

Installing the optimal carburetor for your application and properly tuning it is one of the best ways to maximize your go kart's performance. With the right carb, you'll get the perfect air-fuel mix to unleash the full potential of your engine.

FAQs

What is the main purpose of a carburetor on a go kart?

The carburetor mixes air and fuel in the proper proportions and delivers this air/fuel mixture to the engine. Proper carburetion allows for optimal combustion resulting in maximum power and acceleration.

How can I tell if my carburetor is too rich or too lean?

A rich condition is indicated by black smoke from the exhaust, fouled spark plugs, and poor fuel economy. A lean condition causes backfiring, overheating, and lack of power. Adjusting the fuel mixture screws leans or richens the carb.

What adjustments can I make to tune my carburetor?

Turning the fuel mixture screws, changing jet sizes, and swapping air bleeds are common ways to tune carburetion. Limiting throttle opening and ensuring crisp throttle response also helps optimization.

Should I choose a float bowl or diaphragm carburetor?

Float bowl carbs provide constant fuel flow but may flood. Diaphragms are less prone to flooding but have varying fuel delivery. Float bowls work well for track karts, diaphragms for off-road.

What precautions should I take when installing a new carburetor?

Use a new base gasket, properly align the throttle linkage, securely connect fuel lines, attach choke/throttle cables correctly, and double check all mounting hardware is tight.