Techtonic Hobbies

Experience the thrill of professional motocross

The Losi Promoto-MX 1/4 Scale Motorcycle delivers authentic motocross excitement right to your backyard. This isn't just another RC toy – it's a precision-engineered machine that captures the raw power and agility of real dirt bikes.

What makes this special:

Ready-to-Run Convenience – Everything included: motorcycle, battery, and charger

Eye-Catching Pro Circuit Scheme – Professional racing graphics that turn heads

1/4 Scale Realism – Impressive size and detail that mirrors real motocross bikes

Losi Quality – Trusted brand known for durability and performance

Perfect for:

RC enthusiasts seeking authentic motorcycle action

Collectors who appreciate detailed scale models

Anyone wanting to experience motocross thrills safely

Imagine the satisfaction of mastering jumps, corners, and straightaways with this beautifully crafted machine. The Pro Circuit graphics gleam in the sunlight as you navigate challenging terrain, feeling every bump and turn through precise controls.

Ready to ride straight from the box – just charge the battery and hit the track!

What's in the box?

(1) Losi Promoto-MX Pro Circuit RTR Motorcycle

(1) Spektrum Smart DX3PM Transmitter

(4) AA Transmitter Batteries

(1) Spektrum 5000mAh 2S 7.4V Smart G2 50C LiPo Battery with IC5 Connector

(1) Spektrum Smart S120 USB-C Charger, 1x20W

(1) Bike Stand

(1) Starting Stand

(1) 1/4 Promoto-MX Motorcycle RTR Product Manual

(1) Quick Start Guide

Chain Lube

Tuning Parts

Fork and Shock Tools

MEET THE MONSTER KING!
The legend has evolved, and it’s bigger, tougher, and meaner than ever! The HPI Racing Monster King is here to take the crown, born from the DNA of two fan-favorite platforms: the Wheely King and the Crawler King. By combining the best of the Wheely-King and Crawler King into a single monster truck platform, we’ve created something special for Wheely-King fans!

Built around a refined version of the original Wheely King chassis, the Monster King boasts a new center gearbox with external slipper clutch, enhanced steering geometry, and new hex hardware for easier maintenance. Every change made  with the performance, and fun in mind — from the Lock-Nut suspension mounts that banish E-clips forever, to the rugged new Tredz tires wrapped around wide 2.2” MT wheels.

Topping it all off is the fully licensed Ford Bronco 4400 bodyshell, an RC replica inspired by the real-life Big Kahuna truck, run by Shane England, with the help of RTR Vehicles and Vaughn Gittin Jr. Motorsports. Featuring a detailed interior, internal roll cage, and working LED light bars, this stunning body brings authentic Big Kahuna style and realism to the Monster King.

The Monster King Big Kahuna brings the spirit of the original Wheely King into a new era. Stronger, smoother, and packed with upgrades that fans will appreciate. With its tough solid-axle design, authentic details, and that unmistakable HPI fun factor, it’s ready to tear up any terrain in true monster truck style.

Tredz TRZ 135x86mm tires
No monster truck is complete without a serious set of shoes, and the Monster King Big Kahuna delivers in style. Brand-new 2.2” 56mm wide monster truck wheels give the truck a bold, aggressive stance, perfectly matched to the new Tredz TRZ 135x86mm tires. Designed specifically for the Monster King, these high-grip TRZ tires feature a deep, open tread pattern that provides outstanding traction on dirt, grass, gravel, and asphalt alike. Whether you’re pulling wheelies, climbing rocks, or carving up the backyard, these tyres are built to perform.

Moulded in HPI’s high-quality rubber compound, the new Tredz TRZ tyres strike the perfect balance between soft, grippy feel and long-lasting durability. Combined with the wide wheels for improved stability, they deliver confident handling and predictable control across any terrain — all while giving the Monster King its unmistakable, beefed-up monster truck look.

Fully Licensed Bodyshell & Authentic Graphics
The Big Kahuna name has serious pedigree — and your new HPI Racing Monster King Big Kahuna model brings that legacy straight into your hands. Driven and owned by Shane England out of Powderly, Texas, Big Kahuna made its debut in 2013 and has become a fan-favourite for its daring stunts, bold graphics and surf-culture flair. 

We’ve captured that spirit in a meticulously licensed bodyshell: the Ford Bronco 4400–inspired design that Big Kahuna unveiled for its modern era. Every curve, graphic and detail reflects the real truck’s aesthetic, from the surf-board silhouette to the rugged roll-cage and standout “BIG KAHUNA” brand.

Crafted from high-strength polycarbonate, the bodyshell is screen printed and hand-finished with cutout windows sitting atop a hard-plastic internal roll cage for scale authenticity and durability. You’ll also see working LED lights in the grille and roof-bar, controlled via the transmitter for show-quality lighting on scene.

It’s a full-fidelity tribute to the real Big Kahuna truck, now shrunk to RC scale with all the attitude intact.

The Monster King is easy to drive with the included All-New 4 Channel 2.4Ghz FHSS TF-51 Transmitter. Features:

NEW - 4th Channel - 100 position digital slider,
NEW - Steering Exponential, 
Drop-down steering position for a natural control position,
Foam-covered wheel for extra comfort and grip,
Swappable steering wheel design for left-handers!
Rubber finger and thumb handle grips,
Rubber bumpers on all corners for the highest protection,
Magnetic area for body clips or screws while you work!
Digital on and off switch,
Audible warnings for low power and idle time!
Servo Reverse, EPA, Trims and Dual Rate switches.

The NEW RF-51 receiver features a waterproof silicone inner jacket for use in any weather and a built-in failsafe - Uses the HPI 4-way LED Adaptor to add headlights with the built-in LED Light controller!

• Features
  1/10th Scale Monster Truck
  Fully licenced RTR-Vehicles Ford Bronco 4400 Polycarbonate bodyshell
  with hard plastic cage and driver.
  Updates to the Wheely King/Crawler King chassis
  New centre gearbox configuration
  New external adjustable slipper clutch
  New spur gear cover
  New motor mount plate
  Motor mounting positioning Inserts
  New rear body mount bracing
  New radio box
  New “E-Clip” eliminating lower shock and linkage mounts
  New steering linkage
  New Hex hardware
  New 2.2” 56mm wide MT wheels and Tredz 135x86mm “TRZ” tires.
  Oil-Filled shocks
  Front and rear differentials
  Aluminum blue-anodized lower links
  Higher Carbon content, less flexible upper links
  TF-51 Transmitter and RF-51 Receiver
  SC-3SWP2 Brushed ESC (2S Max recommended for Brushed Motor)
  Brushed 550 12T motor
  LED headlights and roof bar lights included (TX controlled)
  2000mAh Ni-MH pack and USB Charger included
  Metal Geared Steering Servo (6.0V/16kg/MG)