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Lectron Fuel Systems
  • PRODUCTS
    • Carburetor Kits
    • Intake/Reeds/Boots
    • Throttles/Cables/Grips
    • Maintenance & Diagnostic
    • Fuel & Oil Systems
    • Merch & Riding Gear
    • Tools & Carb Parts
    • Request a Custom Quote
  • SUPPORT
    • Tuning Guides/FAQ
    • Schedule a Tech Call
    • Register Your Carb
  • Dealers
    • Find a Dealer
    • Become a Dealer
  • About
    • About
    • Why Lectron
    • FAQ
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BILLETRON HD-X & HD-X+ Carburetors | Give Your Harley or Street Bike an Upgrade

Big torque, crisp throttle, and zero hassle—HD-X carbs are the upgrade your bike was built for.

The BILLETRON HD-X & HD-X+ are built for riders who want more out of their Harley or custom street bike—more torque, more control, more reliability. Whether you're running a stock 96ci motor or a fully built 124ci beast, these carbs deliver smooth power off the line, effortless cruising, and hard-pulling top end without bog or hesitation. They're ideal for riders who want throttle response that feels connected, fuel circuits that adjust on the fly, and a setup that just works—no matter the fuel, elevation, or riding conditions. From daily riders to performance builders and drag racers, the HD-X series is made for those who demand more from every twist of the throttle.

HIGHLIGHTS SUMMARY

⚡ XCELERATOR Rod — Instant response without hesitation, even at low RPMs
🎚️ Idle Fuel Control Circuit – Externally adjustable idle screw controls Idle speed RPM without disassembly
🔃 Chrome-Brass Plated Slide — Reduces friction for buttery-smooth throttle pull
🌄 Auto Elevation Compensation – Performs with swings in altitude, no tuning needed
🔧 Set It & Forget It – No brass jets, no constant tuning — just ride

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FULL HIGHLIGHTS

Xcelerator Metering Rod

Instant Response. No Bog. All Throttle.

Designed to mimic an accelerator pump—without the complexity—the Xcelerator Metering Rod delivers fuel precisely when you need it. Whether you’re rolling it on or whacking it wide open, this circuit reacts instantly for throttle response you didn’t think a carb could deliver.

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Idle Fuel Control Circuit

Dial in Idle. In Seconds.

This externally adjustable circuit lets you fine-tune your idle RPM without pulling the carb or turning off the bike. Whether you're chasing the perfect start or calming down a flameout-prone setup, precise idle control is just a turn away.

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Chrome-Brass Plated Slide

Silky Feel. Built to Last.

A chrome-plated brass slide delivers smooth, low-friction throttle modulation with unmatched durability. It’s designed to resist sticking and wear—so your throttle feels fresh every ride.

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Set It & Forget It

Lectron metering rods are precision machined to tolerances of .0003" - roughly the thickness of one human hair. Our technology automatically compensates for changes in elevation, temperature, and humidity—no jets to swap, no guesswork. Whether you're riding sea level sand or high-elevation singletrack, you’ll get clean, consistent performance every time you start your bike.

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Billet Aluminum Construction

Stronger. Lighter. Built to Perform.

Machined from solid billet aluminum, this body delivers superior strength, tighter tolerances, and a premium finish. It’s lighter, tougher than plastic, and designed to withstand heat, vibration, and abuse—ride after ride.

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Let customers speak for us

from 153 reviews

Works great! The installation of the carb and cable adapter worked perfect. High quality part.

Alex
07/02/2025
Slip-In Throttle Cable Adapter | BILLETRON & PRO-SERIES Carbs
Slip-In Throttle Cable Adapter | BILLETRON & PRO-SERIES Carbs

My 2008 WRF 250 runs amazing after installing this carb! Easy install as well

Chris
07/01/2025
PRO SERIES Carburetor Kit for 4-Stroke | Precision Fuel Delivery, Peak Performance, Ultimate Simplicity (38mm-40mm)
PRO SERIES Carburetor Kit for 4-Stroke | Precision Fuel Delivery, Peak Performance, Ultimate Simplicity (38mm-40mm)

Excellent

C.H.
06/07/2025
BILLETRON Carburetor for 2-Stroke | Quick, Responsive, & Simple (25mm-29mm, 38mm-40mm)
BILLETRON Carburetor for 2-Stroke | Quick, Responsive, & Simple (25mm-29mm, 38mm-40mm)

Love the 29 mm on my stock bore 4 mil stroker crank banshee

Travis
05/29/2025
BILLETRON Carburetor Kit for ATV & Quad | Quick, Responsive, & Simple (29mm, 38mm, 40mm)
BILLETRON Carburetor Kit for ATV & Quad | Quick, Responsive, & Simple (29mm, 38mm, 40mm)
The bike runs absolutely incredible and honestly forget sometimes that it's not fuel injected cau...

First impressions even before tuning the carb I noticed instantly that the bike started up way faster than ever before. And with the stock carburetor Id have to pull the choke and or prime kick it a few times. With the Lectron carb I go and turn my key on and the bike starts within a second or two of touching the e-start. And throttle response was crazy good before tuning as well. No more randomly stalling or cutting out when it was semi cold and doing an almost WOT acceleration. Then after tuning it with the a few email interchanges between Tommy and I Tommy was able to tell me exactly what it needed in order to run cherry. I've never ran or ride a bike with a Lectron carb but after getting a few bugs out the way and can firmly say I 110% percent stand behind these guys and will always use their products and support their products. The bike runs absolutely incredible and honestly forget sometimes that it's not fuel injected cause it runs insanely good. Best thing I've done to my Ktm and plan to do it to my yz125 as well. And I can't thank Tommy enough for all the help and the 15 plus emails that were sent, Tommy's an awesome dude and really appreciate him.

Asa L.
11/07/2024
PRO SERIES Carburetor Kit for 4-Stroke | Precision Fuel Delivery, Peak Performance, Ultimate Simplicity (38mm-40mm)
PRO SERIES Carburetor Kit for 4-Stroke | Precision Fuel Delivery, Peak Performance, Ultimate Simplicity (38mm-40mm)
Outstanding Performance

I bought the 38 Mil Lectron carburetor for my 1986 250R with only a pipe on it. This carburetor really released the true potential on my 250 with its great performance and throttle response. The throttle cable is a tad bit long but thats absolutely fine as it leaves play in the thumb throttle. Super smooth throttle response and cable. This carburetor and how it performs will turn your machine into a whole different kind of animal. I love the tuning on this thing too. Also not having to change jets for different elevations is nice. Never going back to any other carb I definitely recommend!

Ryder
10/02/2024
H-Series Carburetor for 2-Stroke | Linear Power, Rideability, & No-Hassle Simplicity (38mm)
H-Series Carburetor for 2-Stroke | Linear Power, Rideability, & No-Hassle Simplicity (38mm)
1 day to install and tune, i'm good to go

i have an older 2001 DRZ 400 with a large aftermarket fuel tank and a yoshimura exhaust, with the air box opened up for fun, elevation doesn't affect 4-strokes as much but when i i can go from 100' to 4000' in a day of riding its something to considerinstallation was very easy considering that its smaller than a flat side pumper carb, and the bike ran right away, it was a little rich at the start but like any new carburetor it needed to be tuned to my bike and thats where the big difference for me was.the process of tuning my old carburetor took about 2-3 hours to make a change depending on how much of a struggle the intake boot would be, i would have to take off the seat and fuel tank, part of my luggage rack, and exhaust brackets ao i could move the sub-frame te get enough room to get the old carb out of the bike and get the the jets in the float bowl (to spare you the details i couldn't simply rotate my old carb to get access, it HAD to come off), and that was for every adjustment, the old carb was too close to the starter to even get to the air mix screw, it was not fun.now onto the Lectron, i needed the remote choke for my bike due to the larger fuel tank, if your wondering if you need one for your bike just go over it and see if you can easily reach the top of your carb, if you can then you probably dont need it, lectron doesnt list a remote choke for my carb but the sales team contacted me quickly and we worked it out, (it works great BTW), i didn't end up using any of the brackets they sent and isted just tuck it behind the frame.tuning, the important subject here, it couldn't be easier with the lectron, i dont even need to get off the bike to make the small adjustments, i just pull off to the side of the road, give a knob a little twist and im back back on the road again literally 5 seconds, and when i had to do a "major" adjustment i just pulled the tank off (i only need to because of my aftermarket one im sure with a stock tank i woulnt even need to do that) loosen the carb boots so i can rotate the carb and thanks to the easy tune kit i bought with the carb i dont need any more tools to pop off the slide cap, adjust the metering rod and put it back together, its a 30 minute job for a "major" adjustment, and thats only because of my aftermarket fuel tank, if it were a stock one im sure it would be 5 mins tops.in the end if your racing your dirt bike and want every last possible ounce of performance and have hours or days to kill, a shop to work on it in not to mention all the different jets you might need to tune it, then a pumper carb might be for you, but if your like me and just want to go have fun on your bike get a lectron it took 1 day to install and tune and im good to go.

William S.
09/26/2024
PRO SERIES Carburetor Kit for 4-Stroke | Precision Fuel Delivery, Peak Performance, Ultimate Simplicity (38mm-40mm)
PRO SERIES Carburetor Kit for 4-Stroke | Precision Fuel Delivery, Peak Performance, Ultimate Simplicity (38mm-40mm)
I would have to say that it is one of the best performance bolt on's that I have purchased in a l...

Recently purchased the Lectron Billetron PRO-Series carburetor and I would have to say that it is one of the best performance bolt ons that I have purchased in a long time. From the tuning right out of the box to the way it makes my motor about pull my arms out of there sockets when Im getting on the gas, hands down the best carb on the market I would purchase all over again before any other brand of carb.

Robert C.
08/16/2024
PRO SERIES Carburetor Kit for ATV's & Quads | Peak Performance & Ultimate Simplicity (38mm-40mm)
PRO SERIES Carburetor Kit for ATV's & Quads | Peak Performance & Ultimate Simplicity (38mm-40mm)
I never want a non-lectron carb again

Ive heard the hype around the lectron carb for about 7-8 years and as someone who works on power sports as a side job, Ive messed with a few bikes that had these carbs from 2 stokes to 4 strokes bikes and four wheelers. I never did get one till about a year ago and coming from a guy who had rebuilt and tuned hundreds of stock and aftermarket carbs, I never want a non lectron carb again. Adjustments are super easy, even the slide adjustment can be made in less than 5 minutes. Your bike will run smoother and crispier with throttle response like no other. I was a little skeptical about the metering rod technology at first, but Ive yet had to adjust anything at different elevations. Great product thats worth every bit of the money.

Vincent S.
07/24/2024
PRO SERIES Carburetor Kit for 4-Stroke | Precision Fuel Delivery, Peak Performance, Ultimate Simplicity (38mm-40mm)
PRO SERIES Carburetor Kit for 4-Stroke | Precision Fuel Delivery, Peak Performance, Ultimate Simplicity (38mm-40mm)
Xcelerator metering rod upgrade

Have the Lectron 38H on my 2017 KTM 300 xc-w. I was happy with it, but was playing w/ the idea of an upgrade in the future. I came upon information that the xcelerator metering rod from the Pro carb. was availablefor the Lectron 38H & the reviews were all positive. I have to say it's a fantastic 'bang for the buck' modification. I feel more torque & power across the board. I noticed it most when the bike was climbingsome really big hills I used to struggle with. I wish I could have seen the look on my own face when I realized the bikejust seemed to have a LOT more power! I highly recommend trying this xcelerator metering rod. I see no downside.

Steve B
07/05/2024
Metering Rods | PRO-SERIES, BILLETRON, and Legacy Carbs
Metering Rods | PRO-SERIES, BILLETRON, and Legacy Carbs
Blown away!

I was a bit leery, seemed expensive but my Freerides Lectron had lost some of its bottom end hit and I couldnt tune it back.My carb came back looking so new I initially thought theyd swapped mine out for a new carb! I put it on expecting to need to some retuning but it ran perfectly and I didnt even need to touch my idle. Super impressed!

Rick
07/05/2024
2-Stroke Carburetor Rebuild Service | Lectron Products Only
2-Stroke Carburetor Rebuild Service | Lectron Products Only
Well worth it!!

After rebuilding my son's built Kx85, I noticed that the carb was dragging. Even after rebuilding it, still dragged a little. I learned about Lectron and how the carbs don't have jetting. Ordered one and wow!! It brought this bike to life! The throttle is snappier, idle is excellent and the powerband increase is awesome! My loves it and says it's a difference of night and day. Definitely recommend it. Thank you Lectron!!

Elias
06/27/2024
BILLETRON Carburetor for 2-Stroke | Quick, Responsive, & Simple (25mm-29mm, 38mm-40mm)
BILLETRON Carburetor for 2-Stroke | Quick, Responsive, & Simple (25mm-29mm, 38mm-40mm)
2007 DRZ400SM

I had a few issues getting the carb in. Not anything with Lectron. I am just a bit OCD and removing the back frame enough to pull the boot to the engine and air box wasn't giving me enough space to pull them back on all the way. So I removed the whole back frame and drilled 4 holes I'm the Air box and it looks amazing. Was having a few issues with getting the bike started after it was installed so I called Lectron and Hunter was very helpful and told me the setting for the idle screw they had on their bike and waited for me to take an engine bracket off and remove the gas tank to adjust the metering rod. And I let the bike cool down and start it a couple times and it works way better than the stock mikuni carb it had in it.

Jacob
04/25/2024
PRO SERIES Carburetor Kit for 4-Stroke | Precision Fuel Delivery, Peak Performance, Ultimate Simplicity (38mm-40mm)
PRO SERIES Carburetor Kit for 4-Stroke | Precision Fuel Delivery, Peak Performance, Ultimate Simplicity (38mm-40mm)
????????????????

I never would have thought that this metering rod would make this much difference!!!My ole my..If youre on the ropes about getting one, dont hesitate..You will not be sorry!!Im running the latest billetron pro 38 on a 2002 Honda cr250r. X2 torque and this thing pulls so freaking hard thru all gears!!

Boogersugar#75
04/14/2024
Metering Rods | PRO-SERIES, BILLETRON, and Legacy Carbs
Metering Rods | PRO-SERIES, BILLETRON, and Legacy Carbs
Lectron on 93 cr125

Fairly easy installation. Definitely improved throttle response and efficiency. Adds a decent bit of low end torque, which is useful for a 125. Would buy again and would highly recommend.

Ds
01/30/2024
H-Series Carburetor for 2-Stroke | Linear Power, Rideability, & No-Hassle Simplicity (38mm)
H-Series Carburetor for 2-Stroke | Linear Power, Rideability, & No-Hassle Simplicity (38mm)

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