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Micro Racing League

The Micro Racing League (MRL) is a competitive 1/28-scale RC racing league built to bring racers, tracks, and manufacturers together under one unified racing platform.

MRL provides standardized classes, consistent rules, organized competition, and a pathway from local racing to regional and international events. Our purpose is to grow micro RC racing, make competition more accessible, and create a fair and recognizable championship structure for racers across the world.

MRL BOX STOCK

The MRL Box Stock class is designed to provide close, affordable competition using the Kyosho Mini-Z RWD platform. Cars must remain stock except for the specific modifications and optional parts permitted below.

Chassis

  • Kyosho Mini-Z MR03 or MR04 RWD chassis only.
  • Wheelbase must be between 90mm and 102mm.
  • Chassis and suspension components must remain stock unless specifically permitted within these regulations.

Body

  • Full hard bodies are required.
  • Kyosho Auto Scale bodies are permitted.
  • Kyosho White Bodies are permitted.
  • Jomurema GT01 bodies are permitted.
  • Other commercially available full hard bodies are permitted.
  • Lexan windows and/or roof panels are permitted.
  • Wheels and tires must remain within the body when viewed from above.
  • Excessive removal of body material for the purpose of weight reduction is prohibited. Normal trimming for chassis, wheel, tire, and body fitment is permitted.

Motor & Electronics

  • Kyosho MZ9P and MZ9E motors only.
  • Motors must remain factory stock internally.
  • Motors may not be opened, rewound, re-timed, internally modified, or otherwise altered to increase performance.
  • Removal of the factory thermal protector is permitted.
  • Direct soldering of motor wires is permitted.
  • The original Kyosho MR03/MR04 receiver/ESC board must be used.
  • ESC/receiver board modifications are prohibited.
  • Aftermarket ESCs and receiver systems are prohibited.
  • Gyros and other electronic driving-assistance systems are prohibited.

Differential & Drivetrain

  • Original Kyosho stock gear differential only.
  • Ball differentials are prohibited.
  • Aftermarket or upgraded differentials are prohibited.
  • Differential modifications intended to alter its performance are prohibited.
  • All drivetrain components must remain stock unless specifically permitted within these regulations.

Wheels

  • Any commercially available production wheel may be used, including Kyosho, PN Racing, Reflex Racing, and similar production wheels.
  • Maximum front wheel width: 8.5mm.
  • Maximum rear wheel width: 11mm.
  • Wheel offset is unrestricted provided the wheel and tire remain completely within the body when viewed from above.
  • Aftermarket aluminum wheel nuts are permitted.

Tires

  • Any commercially available production tire may be used.
  • Tires must be properly fitted to the corresponding wheels.
  • Tire warming is permitted.
  • Tires may be cleaned using a 50–70% isopropyl alcohol solution.
  • Tire additives, traction compounds, or other chemical performance treatments are prohibited.

Transmitter

  • Kyosho KT-531P transmitter only.
  • The transmitter must remain stock.
  • Transmitter modifications are prohibited.

Batteries

  • Four (4) AAA rechargeable NiMH cells only.
  • Cells must have a nominal voltage of approximately 1.2V per cell.
  • LiPo, LiHV, Li-ion, alkaline, or other battery chemistries are prohibited.
  • Battery modifications are prohibited.

Permitted Optional Parts & Modifications

The following upgrades and tuning components are permitted:

  • Any production ball bearings (such as Kyosho, PN, FastEddy, etc).
  • Aluminum wheel nuts.
  • Kyosho only aluminum 0-degree steering knuckles.
  • Plastic, carbon fiber, steel, or fiberglass T-plates.
  • Kyosho or PN Racing front springs.
  • Tire and wheel changes permitted under the Wheel and Tire regulations above.
  • Direct soldering of the motor.
  • Removal of the motor thermal protector.

Minimum Weight

  • Minimum race-ready weight: TBD
  • Weight is measured with the body installed and all four batteries installed.
  • The car must meet minimum weight immediately before and after racing.
  • Brass, tungsten, or other material weights can not be added/installed.

General

Unless a modification, component, or upgrade is specifically permitted within these regulations, it is prohibited.

The intent of MRL Box Stock is to maintain the fundamental performance and simplicity of the factory Kyosho Mini-Z RWD platform while allowing limited tuning for handling, reliability, and tire selection.

MRL officials reserve the right to inspect any vehicle, motor, electronics, batteries, or other components for compliance at any time during an MRL-sanctioned event.

MRL 2500 LIPO

MRL LiPo 2500 is a competitive 1/28-scale class built around open chassis tuning with a controlled 2500KV power system. The class is intended to encourage chassis development and setup freedom while maintaining close, consistent racing.

Chassis

  • Any commercially available 1/28-scale 2WD chassis is permitted.
  • 90mm to 102mm wheelbase permitted.
  • Chassis tuning and aftermarket components are permitted.
  • Custom and aftermarket suspension components are permitted.

Body

  • Full hard bodies are required.
  • Kyosho Auto Scale and White Bodies are permitted.
  • Jomurema GT01 bodies are permitted.
  • Other commercially available full hard bodies are permitted.
  • Lexan windows and/or roof panels are permitted.
  • Wheels and tires must remain within the body when viewed from above.
  • Full lexan bodies are prohibited.

Motor

  • Brushless motors rated at 2500KV (max 2750KV).
  • Motor must be commercially available as a production 2500KV motor.
  • Motor rewinding or internal modification is prohibited.
  • Motor timing must remain at the manufacturer's factory specification.
  • Motors may be inspected or tested by MRL officials at any time.

ESC

  • Any commercially available brushless ESC is permitted.
  • ESC must operate in Blinky / Zero Timing mode.
  • Boost, turbo, dynamic timing, or other electronic timing advancement is prohibited.
  • ESC firmware may be inspected by MRL officials.

Drivetrain

  • 2WD only.
  • Any commercially available differential is permitted.
  • Ball and gear differentials are permitted.
  • Aftermarket drivetrain components are permitted.

Gearing

  • Any production 1/28 scale manufacturer pinion and spur gear permitted.
  • Tooth count must be distinguishable by PN color or marked/engraved (titanium allowed).
  • 12T Pinion / 53T Spur

Wheels

  • Any commercially available production wheels are permitted.
  • Maximum front width: 8.5mm.
  • Maximum rear width: 11mm.
  • Wheels and tires must remain within the body when viewed from above.

Tires

  • Any commercially available production tires are permitted.
  • Tires must be properly fitted to the wheels.
  • Tire warming is permitted.
  • Tires may be cleaned using a 50–70% isopropyl alcohol solution.
  • Tire additives and traction compounds are prohibited.

Batteries

  • 2S LiPo batteries only.
  • Maximum nominal voltage: 7.4V.
  • Maximum charge voltage: 8.40V.
  • High voltage batteries not permitted.
  • Batteries must be commercially available production batteries.
  • Modified or altered battery packs are prohibited.

Radio & Receiver

  • Any commercially available transmitter and receiver system is permitted.
  • Gyros and electronic driving-assistance systems are prohibited.

Minimum Weight

  • Minimum race-ready weight: 160 grams
  • Weight is measured with the body and battery installed.
  • Additional securely mounted ballast is permitted.

General

Chassis setup and tuning are open unless specifically restricted within these regulations.

MRL officials reserve the right to inspect motors, ESCs, batteries, electronics, gearing, chassis, or other components at any time during an MRL-sanctioned event.

MRL 3500 LIPO

MRL LiPo 3500 is a competitive 1/28-scale class built around open chassis tuning with a controlled 3500KV power system. The class is intended to encourage chassis development and setup freedom while maintaining close, consistent racing.

Chassis

  • Any commercially available 1/28-scale 2WD chassis is permitted.
  • 98mm and 102mm wheelbases permitted.
  • Chassis tuning and aftermarket components are permitted.
  • Custom and aftermarket suspension components are permitted.

Body

  • Any commercially available 1/28-scale Lexan GT-style body is permitted.
  • Body must match the 98mm or 102mm wheelbase of the chassis.
  • Wheels and tires must remain within the body when viewed from above.
  • Maximum wing height: 45mm from the racing surface.

Motor

  • Any commercially available 1/28-scale 3500KV sensored brushless motor is permitted.
  • Maximum motor can diameter: 15mm.
  • Maximum measured motor KV: 3750KV.
  • Aftermarket rotors are prohibited.
  • Motor rewinding or internal modification is prohibited.
  • Motors may be inspected or tested by MRL officials at any time.

ESC

  • Any commercially available 1/28-scale brushless ESC is permitted.
  • ESC timing, boost, and turbo functions are permitted.
  • ESC firmware and settings may be inspected by MRL officials.

Drivetrain

  • 2WD only.
  • Any commercially available differential is permitted.
  • Ball and gear differentials are permitted.
  • Aftermarket drivetrain components are permitted.

Gearing

  • Standard gearing: 14T pinion / 53T spur.
  • MRL may specify an alternate gear ratio for an event based on track size or conditions.
  • Any commercially available pinion and spur gears are permitted.
  • Gear tooth counts must be clearly identifiable for technical inspection.
  • Gearing may be inspected and marked by MRL officials before competition.

Wheels

  • Any commercially available production 1/28-scale wheels are permitted.
  • Maximum front width: 8.5mm.
  • Maximum rear width: 11mm.
  • Wheel diameter: 19mm to 20mm.
  • Wheels and tires must remain within the body when viewed from above.

Tires

  • Any commercially available production rubber tires are permitted.
  • Maximum mounted tire diameter: 25.5mm.
  • Maximum front tire width: 8.5mm.
  • Maximum rear tire width: 11mm.
  • Tires must be properly fitted to the wheels.
  • Tire warming is permitted.
  • Tires may be cleaned using water or up to 70% isopropyl alcohol.
  • Tire additives and traction compounds are prohibited.
  • Foam, silicone, urethane, homemade tires, and tire inserts are prohibited.

Batteries

  • 2S LiPo batteries only.
  • Two 1S LiPo cells connected in series are permitted.
  • Maximum charge voltage: 8.40V.
  • Maximum capacity: 500mAh.
  • Maximum battery dimensions: 45 × 24 × 13mm.
  • Batteries must be commercially available production batteries intended for micro/1/28-scale RC use.
  • Modified or altered battery packs are prohibited.
  • A separate battery may be used solely to power the race transponder.

Radio & Receiver

  • Any commercially available transmitter and receiver system is permitted.
  • Gyros and electronic driving-assistance systems are prohibited.

Minimum Weight

  • Minimum race-ready weight: 160 grams.
  • Weight is measured with the body and battery installed.
  • Additional securely mounted ballast is permitted.

General

Chassis setup and tuning are open unless specifically restricted within these regulations.

MRL officials reserve the right to inspect motors, ESCs, batteries, electronics, gearing, chassis, or other components at any time during an MRL-sanctioned event.

Buggy Racing Rules

Condition & Tires

Before driving, all buggies require staff inspection. Tires must be indoor-only use, you may not drive outdoor-driven cars on the track. Foam tires are required & available for sale at PyroRC.

Allowed Modifications

Any body may be used. We allow all shock/spring upgrades. No ESC, motor, or battery modifications. Foam tires required. All other upgrades are open. Transponder & connect cable required to race.

Buggy Days

Tuesdays are buggy-only. There will be ramps & jumps placed across the track all-day to accommodate open practice before buggy racing.

Buggies can not be raced or used on the track on other days, except when announced or pre-approved by staff.