Lectron Downdraft Carburetor Kits for Drag Racing and Karting

Custom Performance. Power How You Want It.
Our Downdraft Carburetor Kits are engineered for riders and builders who demand a custom-fit solution for unique engine configurations. Whether you’re running drag bikes, speedway machines, or kart engines, each kit is built-to-order using components from our proven product lines.

Available in sizes 34, 36, 38, 40, 44, 48, 52–50, 52, 54, 56, 58mm these carburetors scale with your performance needs. Models 48mm and larger are CNC-machined from billet aluminum for maximum durability. With each size, there includes an option of our 45° or 90° Downdraft carburetors.

Every kit is configured around your engine’s dimensions, displacement, and performance goals. After a quick measurement and setup process, we assemble and ship a complete kit tailored specifically to your build.

🏁 Ideal For: Kart racers, drag racers, and speedway riders who need a high-quality, race-ready carburetor that delivers consistent performance.

*For Drag Racing and Karting Use Only

Metering Rod

The Standard Metering Rod is a key component of our dual-circuit fueling system, engineered for smooth throttle response and clean power delivery. Positioned directly in the manifold pressure zone, it responds instantly to changes in throttle input, drawing fuel based on airflow velocity and engine load.

The rod’s contoured surface and precision grind control the fuel pickup signal with exceptional accuracy. As airflow increases, the rod delivers atomized fuel in a fine vapor—optimizing combustion, improving throttle snap, and eliminating flat spots.

Unlike traditional carburetors with overlapping circuits, the Standard Metering Rod delivers a linear fueling curvewithout hesitation or surge. This design enhances rideability, fuel economy, and power across the entire RPM range.

Power Jet System

Adds external adjustability of fuel for wide-open throttle positions. Fine tune your top end for increased power without sacrificing midrange - Ideal for racing and high-speed performance.

No-Jetting

Our carburetors use a dynamic fuel delivery system that self-compensates for changing conditions like altitude, temperature, and humidity. Unlike traditional carbs that require constant jetting adjustments, ours deliver consistent fueling with no extra effort.

Just bolt it on and go — whether you’re riding at sea level or climbing elevation.

Proven Performance

Our carburetors are built on well-established fuel delivery principles that have been tested across countless on and off-road applications. Whether you're racing, trail riding, or running a custom build, you can count on predictable throttle response, smooth power delivery, awesome peak power, and long-term reliability.

This is performance you can feel — without needing to overthink it.

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FAQ

Will the carb run perfect out of the box?

Each Lectron carb is built and pre-set using the specs you provide. While we aim for true plug-and-play, engine condition and maintenance—like worn reeds, tired top ends, or leaking seals—can affect performance. Minor tuning is recommended after install to dial things in, but once it's set, it stays set. No jets. No guesswork.

Do I need to drain the fuel from my float bowl?

Yes, if you plan to leave the bike sitting for more than a few weeks it is recommended to drain the fuel from your bowl. This will increase the life of the components within it.

What is the factory starting length for my metering rod?

Each rod will have a different starting length and will vary based on the batch and what we think is a good tune based off of your specs. They are always measured from the tip of the rod to the brass ring on the slide in inches (to the thousandth). Do not collapse the spring when measuring. The starting length can be found based on the carb serial number if ordered from a supplier, or if ordered directly from Lectron, it will be on your invoice and stored electronically in our system.

Will the carb come pre-tuned?

We have over 50 years of experience with tuning carburetors. We setup each carb to a fundamentally determined setting based on information you provide to us. Your carb will be very close or spot on when received. With that said, varying factors like the bikes condition, wear, maintenance, oil ratio, and age of fuel can have an effect with tuning. We suggest a simple, slight tuning at install to achieve max performance and preferability. Once you set it, forget it. Enjoy no-hassle.

Lectron Downdraft Carburetor Kits for Drag Racing and Karting | Custom 1-4 Cylinder Performance Upgrade (30mm - 59mm)