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PRO-SERIES Carburetor for 2-Stroke | Max Performance & Precision (38mm-40mm)

PRO-SERIES Carburetor for 2-Stroke | Max Performance & Precision (38mm-40mm)
TPS (Throttle Position Sensor)
PRO-SERIES Carburetor for 2-Stroke | Max Performance & Precision (38mm-40mm)
PRO-SERIES Carburetor for 2-Stroke | Max Performance & Precision (38mm-40mm)
TPS (Throttle Position Sensor)
PRO-SERIES Carburetor for 2-Stroke | Max Performance & Precision (38mm-40mm)
74900

For Riders Who Want

The PRO-SERIES delivers unmatched throttle response, torque, and top-end power through a precision-machined billet bore design and advanced internal fuel circuitry. Every component is purpose-built for performance, including a fully integrated dual-jet system, and proprietary Xcelerator metering rod. It’s our most responsive, most refined, and most race-ready carburetor. Power made easy.

Description Features + Compatability Chart Specs FAQ
Includes

Kit Includes

  • (1) PRO-SERIES 2-STROKE Carburetor Setup For Vehicle
  • (2) Lectron stickers
  • (1) PRO-SERIES Tuning Guide

*ATV Kits will include a throttle cable. Required for function with ATV's.

Unleash Maximum Performance for Your 2-Stroke Engine

The Lectron PRO-SERIES carburetor is the ultimate high-performance carburetor for 125cc-500cc 2-stroke engines. Engineered for instant throttle response, increased horsepower, and unmatched rideability with effortless external adjustments that take out the hassle. This carburetor is built for racers, trail riders, weekend warriors, and serious performance enthusiasts. 

With precision airflow dynamics, the XCELERATOR Metering Rod, and cutting-edge Torque Jet system, The PRO-SERIES line up optimizes fuel delivery to give you explosive acceleration and seamless power across all RPM's.

🏁 Who It's For:

Riders who want race-grade power, quick throttle response, and full adjustability in a premium package. Ideal for 125cc–500cc 2-stroke applications.

 

Xcelerator Metering Rod

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.

Torque Jet Technology + Power Jet System

Torque Jet Technology + Power Jet System

The PRO-SERIES combines our newly designed Torque Jet Technology in addition to the Power Jet System. Designed to deliver power exactly where you need it — the bottom-end grunt and wide-open throttle performance is unrivaled. The torque jet design activates at low throttle openings to improve off-idle response and drive out of corners, while the power jet kicks in at higher RPMs to maintain strong top-end fueling without bog or drop-off.

Together, these two circuits and the Xcelerator Metering Rod create an incredibly responsive throttle at all RPM and put real power to the ground without hesitation. Whether you're trail riding, racing MX, or pushing through deep sand, the PRO-SERIES is designed for performance, and delivers.

Internal Fuel Circuits

Internal Fuel Circuits

Fully optimized internal fuel circuit routing, meaning the power jet and torque jet systems are fed through machined passages inside the carburetor body — not external hoses. These fuel passages have been designed to expedite fuel delivery by reducing the required vacuum necessary to pull fuel through each circuit and also shortens the fuel travel path which allows for near immediate fuel delivery. The result, a noticeably quicker throttle response and immediate power transfer to the ground.

By eliminating external fuel hoses, the PRO-SERIES not only looks cleaner but is also easier to install and less prone to hose-related damage in harsh riding conditions.

Tailored Bore Design

Tailored Bore Design

Unlike one-size-fits-most OEM carbs, our bore is precision-tailored to match your engine's air volume for sharper throttle response and better power delivery.

It's like a well fitted suit vs one from your dad's closet - mass applied sizing doesn't cut it.

Avoid the pitfalls of generic carbs. Get fitted.

Redirect Slide Ramp

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.

Carb Sizes: Which One is Right?

Short Body / New Style

Short Body / New Style

  • 78mm Overall Length
  • 46mm OD Spigot (Engine Side)
  • 62mm OD Bell (Airbox Side)

The BILLETRON and PRO-SERIES Short-Body carbs are designed to replace modern OEM carburetors in the 36mm–40mm range. With a more compact overall length, they’re a direct fit for newer bikes and ATVs where space is tighter—especially behind the shock. These carbs deliver massive gains in throttle response, torque, and top-end without sacrificing fitment.

Common OEM carbs replaced:

  • Keihin PWK 36
  • Keihin PWK 38
  • Mikuni TMX 36
  • Mikuni TMX 38
  • Other 36–40mm short-body OEM carbs

Example fitments:

  • 2021 YZ 250
  • 2017 KTM 300 XC
Long Body / Old Style

Long Body / Old Style

  • 90mm Overall Length
  • 46mm OD Spigot (Engine Side)
  • 62mm OD Bell (Airbox Side)

The BILLETRON and PRO-SERIES Long Body carbs feature a 90mm overall length and are designed for older bikes that originally came with longer carburetors. With a 46mm spigot outer diameter, they fit most aftermarket reed cages and select OEM intake manifolds. These carbs are ideal for riders upgrading from older 34mm–38mm carbs and looking for modern performance in a compatible form factor.

Common OEM carbs replaced:

  • Keihin PWK 38 Air Striker (Standard Body)
  • Mikuni TMX 38 (Early Models)
  • Keihin PJ 36/38
  • Mikuni VM 36/38
  • Other OEM carbs from the 90s and early 2000s with similar dimensions

Common fitments:

  • Older 2-stroke bikes from the 1990s to early 2000s
  • Vintage builds and restorations using aftermarket reed cages

Modular Fitment:The adapter extension is removable, allowing the carb to convert fromLong Body (90mm)toShort Body (78mm)if needed. This makes it ideal for riders who want fitment flexibility without buying another carb.

Note:
Many OEM intake manifolds on bikes 20+ years old require a 43mm spigot outer diameter. For those applications, the Long Body - V version is recommended for proper fit without modifying the intake boot.

If you're upgrading from a vintage 36–40mm carb and need a longer overall length for proper throttle cable alignment and manifold fitment, the Long Body is your go-to.

Long Body - V

  • 90mm Overall Length
  • 43mm OD Spigot (Engine Side)
  • 62mm OD Bell (Airbox Side)

The BILLETRON and PRO-SERIES Long Body - V are built specifically for older 2-stroke bikes that require a 43mm spigot outer diameter to fit OEM intake manifolds. With a 90mm overall length and permanent adapter, this version is a direct replacement for many vintage setups—no boot stretching or manifold modification required.

Common OEM carbs replaced:

  • Keihin PWK 36/38 (Early models)
  • Keihin PJ 36/38
  • Mikuni TMX 36/38
  • Mikuni VM 36/38
  • Other OEM carbs from the 80s, 90s, and early 2000s with 43mm spigot fitment

Common fitments:

  • 1990s–early 2000s 2-stroke bikes using OEM intake manifolds
  • Vintage builds and restorations where OEM fitment is critical

Key Fitment Notes:

  • Features a fixed 43mm OD spigot for seamless installation with OEM intake boots
  • Adapter is non-removable, ensuring proper length and consistent fit
  • Maintains the same 90mm overall length as the standard Long Body version for throttle cable alignment and vintage geometry

If your bike was originally equipped with a 36–38mm carb and uses a 43mm OEM intake boot, the Long Body - V is the most accurate and hassle-free upgrade available. Built for legacy fitment—no compromises.

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FAQ

+ Will the PRO-SERIES work with my OEM cable?

The PRO-SERIES 2-Stroke can be used with your OEM cable. If you have a slip-in cable, you may require a slip-in cable adapter or a threaded throttle cable.

+ 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.

+ How is the PRO-SERIES different then the H-Series or BILLETRON?

The PRO SERIES is our top-tier 2-stroke carburetor - built from the ground up for maximum performance, throttle response, and durability. Compared to the H-Series, which offers great simplicity and value, the PRO uses precision billet construction, advanced fuel metering, and displacement-matched bore design for sharper response and more refined power delivery. Versus the Billetron, which shares billet construction of the PRO and simplified fuel metering of the H-Series, the PRO introduces precision fuel delivery and adjustability for all throttle positions and RPM ranges. This results in next level throttle response, acceleration, and overall power. These PRO features also allow flexibility and is highly adaptable to changing fuels, upgrades, and performance modifications all within seconds.

+ 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.

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Customer Reviews

Based on 24 reviews
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Will G
Thanks for your help Lectron !!!

My thoughts on Lectron. My bike is a 2022 Beta 300RR. Stock motor. I originally had some concerns about the Billetron Pro with the new throttle position sensor because it would be controlling my oil injection. I called and talked to one of their tech guys and he explained how it works and how the Beta responds if it wherever to come unplugged. He took the time to explain it to me before I ordered it. He was very helpful, and I appreciate that. So, I ordered one up.Shipping was quick and I put it right on the bike. Fitment was great.Bike fired right up. The carb ran great right out of the box. A tiny bit rich on the bottom end but was easy to adjust it on the trail.The carb made a fantastic difference in the bikes performance. Very good addition to the bike. Great service , Great product.

c
crujones7
Bottom End

I ride a 2020 Yamaha YZ125X that had the Mikuni TMX. I also had the Lectron H-Series, but was missing the grunt down low thats comparable to a PWK Airstriker 36mm or 38mm. Once the addition of the Torque Jet was introduced, the playing field was leveled. The XCELERATOR Metering Rod added is the game changer adding an extra dose/charge, whatever you want to call it, of fuel to not bog, stutter, load the motor. The best description is a 36mm below mid rpm & 38mm above it with room to spare up top at 12,700rpm. The added metering rod feels like a high comp head(I run a high volume dome with low compression). I have sold my PWK A/S mic dropped.

R
Rob B
Best carb ever!

Absolutely the best. This makes an old bike run better than a new fuel injected bike.

B
Brian M
Billetron Pro-series KDX 200-220 testimonial

Just wanted to let you know that I got the Lectron installed on my KDX200 and it runs amazing! No more stuttering at lower RPMs!!! Thanks again for all your helpBrian

T
Tyler L.
Runs Great!!

Ive been hyped with my Pro, stepped up my bikes performance to a level I didnt know it had. So much more low-end torque and the power band still hits! I installed it then did some riding in Austin, Texas. I recently moved to Denver, Colorado and it runs great even with the elevation change. Didnt have to make any adjustments despite the elevation change.

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