.product_section .product_form, .product_gallery { opacity: 1; } .multi_select, form .select { display: block !important; } .image-element__wrap { display: none; }

Lectron HD-X Carburetor Kit for Harley Davidson & Similar | Powerful, Responsive, & No Jetting Simplicity (56ci - 124ci)

Harley Davidson Carburetor - Performance Upgrade - Lectron Fuel Systems Billetron® Pro-Series HD-X

.price-ui--loading { display: block !important; opacity: 1 !important; }

89999

For Riders Who Want

Designed specifically for performance street bike applications, the BILLETRON HD-X delivers strong off-idle response, smooth cruising, and wide-open throttle performance in a simple, easy-to-tune package.

Featuring a three-circuit fuel system — including the Xcelerator Metering Rod, power jet, and an adjustable Idle Fuel Control Screw — the HD-X offers precise control without the need for complex tuning. It comes as a complete kit with throttle cable, 2bolt, 3bolt, and more. Offering riders a clean, responsive upgrade with modern tuning capability and classic mechanical reliability.

Includes

Kit Includes

(1) HD-X/HD-X+ Carburetor Setup for your bike
(1) Throttle Cable (length of your choice)
(1) 2-Bolt Manifold
(1) 3-Bolt Manifold with Shims
(2) Lectron stickers
(1) Tuning Guide

Torque. Control. Simplicity.
The BILLETRON HD-X Series is purpose-built for Harley Davidson and similar large-displacement engines, delivering strong low-end torque, clean throttle response, and minimal tuning. The HD-X supports up to 96ci engines, while the HD-X+ is optimized for high-output builds up to 124ci with a custom larger bore for increased airflow.

With three precision fuel circuits — the externally adjustable Idle Fuel Control, Xcelerator™ Metering Rod, and Power Pet — this carburetor gives you total control over fuel delivery while remaining incredibly easy to set up and ride.

🏁 Who It’s For:

Street riders and builders who want bolt-on power, smooth control, and zero jetting hassle — whether you’re cruising a stock 96ci or pushing a 124ci big-bore build.

IFC: Idle Fuel Control

Unlike sealed-off idle circuits or carbs that require disassembly to make changes, our externally adjustable Idle Fuel Control gives you direct access to fine-tune low-RPM fuel delivery on the fly. Need to bump idle up after a cam swap or richen things for cold starts? A simple turn of the screw does it.

This isn’t a “set-it-and-pray” system — it’s precision control where it matters most.

Don’t settle for a carb that idles how it wants. Dial it in. Get control.

Xcelerator Metering Rod

Provides a burst of fuel enrichment when ‘whacking’ the throttle for instant throttle response in all RPM’s. This innovation is a leap in metering rod technology by sustaining the hassle-free, no jetting benefits, while leveling up performance and throttle response. No compromise, just power made easy.

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.

Redirect Slide Ramp

Designed exclusively for our PRO-SERIES & BILLETRON carburetors, this unique slide design does more than control throttle - it redirects airflow to sharpen the fuel signal, delivering quicker, cleaner throttle response and more consistent power delivery across the rev range.

Chrome Plated Brass 'H' Slide

Throttle feel starts at the slide — and this one’s built to deliver. The chrome-plated brass ‘H’ slide adds durable mass for a more stable, weighted response, while the chrome finish drastically reduces friction to prevent sticking or galling under heat.

The result? A buttery-smooth throttle pull that stays consistent, even in the harshest conditions.

Don’t settle for flimsy or grabby. Feel the difference. Ride smoother.

Carb Sizes: Which One is Right?

HD-X (54ci-96ci)

99mm Overall Length
48mm Spigot OD
62mm Bell OD

The HD-X carburetor is designed for high-performance engines from 54ci to 96ci, including Harley-Davidsons and similar street bikes. With a 99mm overall length, 48mm spigot OD, and a 62mm bell OD, the HD-X delivers excellent throttle response, smoother fueling, and more top-end power—while retaining compatibility with most aftermarket manifolds and air filter setups. Intake 2-bolt and air filter 3 bolt is included in the kit.

Common OEM carbs replaced:

Keihin CV40

Mikuni HSR42 / HSR45

S&S Super E / Super G

Harley OEM 40mm Constant Velocity

Other 40–45mm aftermarket Harley carbs

Example fitments:

Harley-Davidson Sportster (883 / 1200, with intake mods)

Harley-Davidson Dyna (Evo & early Twin Cam)

Harley-Davidson Softail (Evolution & early Twin Cam)

Harley-Davidson FXR / FXD (carbureted models)

Big Dog, Ironhorse, and other custom V-twin builds using 54ci–96ci engines

Custom single-carb shovelhead and Evo choppers

HD-X+ (96ci-124ci)

99mm Overall Length
48mm Spigot OD
62mm Bell OD

The HD-X+ is built for large-displacement V-twin engines from 96ci to 124ci, including big-inch Harley-Davidsons and custom choppers. With an oversized flow path and enhanced internal volume, it delivers the fuel these engines demand—without sacrificing rideability. The HD-X+ shares the same external dimensions as the HD-X: 99mm overall length, 48mm spigot OD, and 62mm bell OD, making it a bolt-on upgrade for many performance builds.

Common OEM carbs replaced:

S&S Super G

Mikuni HSR45 / HSR48

Keihin 42–45mm performance CV carbs

Custom bored-out Harley OEM or aftermarket carbs

Example fitments:

Harley-Davidson Twin Cam 96ci / 103ci / 110ci (carb-converted)

Harley-Davidson S&S 124 / 126 builds

Custom Evo choppers with big-inch stroker motors

Big Dog, Indian (carb-era), and aftermarket V-twin frames using 100ci+ crate engines

Aggressive drag or street builds running methanol or high-flow heads

… …

FAQ

+ Will the HD-X work with my OEM throttle assembly?

Yes, the HD-X is compatible with most OEM throttle assemblies. However, we do not recommend removing the cruise control stop from your throttle to achieve full pull. Doing so can cause excessive tension, leading to premature wear on the throttle cable and reduced overall lifespan. For best performance and durability, using the included throttle and cable that come with the HD-X kit is required.

+ What's the difference between Lectron carbs and stock/OEM carbs?

Lectron carbs are built for riders who want simplicity without compromising performance.

Unlike stock carbs that rely on jets and constant tuning, Lectron uses a metering rod system that automatically adjusts fuel delivery based the conditions around you (elevation, temperature, humidity, etc..) . No jets to swap. No guessing. Just ride.

Here’s what sets us apart:

No Jetting Required – Adapts to changes in altitude, temperature, and mods automatically.
Smooth, Predictable Power – Strong bottom-end and midrange torque with linear throttle response.
Fewer Parts, Less Tuning – Simpler design means less time wrenching and more time riding.
Built for Performance – Whether you're racing or trail riding, you get better performance without the hassle.

It’s the performance you want, with the simplicity you’ve been missing.

+ What type of fuel is recommended for 4-Strokes?

We recommend using premium fuel with a minimum octane rating of 91 for all 4-stroke applications. Lower-quality or low-octane fuel can cause tuning issues, poor performance, and starting problems—not just with our carburetors, but with any carb system. For the best results, stick with fresh, high-quality fuel to ensure consistent combustion and optimal throttle response.

+ What if I need help with install or tuning?

No problem - we've got you covered. Our dedicated support team has extensive experience tuning and installing Lectron carburetors across a wide range of bikes and riding styles. Whether you're working through your initial setup or fine-tuning for specific conditions, we're here to help. Reach out anytime - we'll make sure your carb is dialed in and your bike runs like it should.

+ 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.

Discover more products

… …