1. Introducció
This manual provides essential information for the safe and effective use, maintenance, and care of your HJC C91 Solid Modular Motorcycle Helmet. Please read this manual thoroughly before using your helmet and retain it for future reference.
The HJC C91 helmet is designed to offer advanced protection and comfort for motorcycle riders. It features a modular design, allowing for versatility between full-face and open-face configurations, along with integrated sun protection and a sophisticated ventilation system.
2. Informació de seguretat
DOT-APPROVED FOR MAXIMUM SAFETY: The HJC C91 helmet meets stringent U.S. Department of Transportation (DOT) FMVSS No. 218 standards. This means it has been rigorously tested for top-level protection, including energy absorption, penetration resistance, and secure chin strap testing. Always ensure the helmet is properly fastened before riding.
Avís legal: Aquest article compleix amb la norma federal de seguretat de vehicles de motor dels EUA 218 (FMVSS 218) (certificat DOT FMVSS núm. 218).
Always wear appropriate protective gear when riding a motorcycle. Never ride with the modular chin bar in the open position at high speeds.
3. Components mésview
Familiarize yourself with the main components of your HJC C91 helmet:
- Advanced Polycarbonate Composite Shell: Ajust lleuger i còmode.
- HJ-17 Pinlock Shield: Offers 99% UV protection, prepared for Pinlock anti-fog insert (sold separately).
- Visera solar integrada: Black dark smoke, anti-scratch coated, deploys quickly.
- Modular Chin Bar: Easily adjustable with CAD technology.
- RapidFire Shield Replacement System: For fast, tool-free shield changes.
- Moisture-Wicking Interior: Removable and washable cheek and crown pads.
- Advanced Channeling Ventilation System (ACS): Front-to-back airflow.
- Butxaques dels altaveus: Smart HJC ready for 10B or 20B Bluetooth systems (sold separately).
- Quick-Release Chin Strap: For easy and secure fastening.

Figura 3.1: Part frontal view of the HJC C91 Modular Motorcycle Helmet. This image highlights the overall shape, clear face shield, and modular chin bar.
4. Configuració i ús inicial
4.1. Wearing the Helmet
- Ensure the modular chin bar is in the open (up) position.
- Grasp the helmet by the chin straps and place it over your head, ensuring a snug but comfortable fit.
- Pull the chin bar down until it securely locks into place.
4.2. Adjusting the Chin Strap
The helmet features a quick-release chin strap for convenience and security.
- Fasten the chin strap by inserting the male end into the female buckle until it clicks.
- Adjust the strap length to ensure a snug fit under your chin. The strap should be tight enough that the helmet cannot be easily rolled off your head.
- To release, pull the red tab on the buckle.
4.3. Visor Operation
The helmet is equipped with a clear outer shield and an integrated dark smoke sun visor.
- Clear Shield (HJ-17): Can be raised or lowered to multiple positions. It provides 99% UV protection.
- Integrated Sun Visor (HJ-V5): To deploy the sun visor, locate the slider mechanism on the top-left side of the helmet and slide it forward. To retract, slide it backward. Use the sun visor only in bright daylight conditions.

Figura 4.1: lateral view of the HJC C91 helmet with the modular chin bar raised, demonstrating its versatility.
5. Instruccions de funcionament
5.1. Modular Chin Bar Usage
The modular chin bar allows you to switch between a full-face and open-face helmet. To raise the chin bar, locate the release button (usually at the center front of the chin bar) and press it while lifting the chin bar upwards until it locks into the open position. To lower, pull the chin bar down until it securely latches.
Precaució: Always ensure the chin bar is fully locked in either the up or down position before riding. Riding with a partially latched chin bar can be dangerous.
5.2. Ventilation System (ACS)
The Advanced Channeling Ventilation System provides front-to-back airflow to expel heat and humidity, keeping you cool. Adjust the vents located on the chin bar, forehead, and rear of the helmet to control airflow. Open vents for maximum cooling, close them for warmth or rain protection.

Figura 5.1: posterior view of the HJC C91 helmet, highlighting the exhaust vents for the Advanced Channeling Ventilation System.
5.3. Smart HJC Bluetooth System (Sold Separately)
The HJC C91 Helmet features speaker pockets and is Smart HJC ready, making it compatible with the 10B or 20B Bluetooth systems (sold separately). Refer to the specific Bluetooth system's manual for installation and operation instructions.
6. Manteniment
6.1. Cleaning the Helmet Exterior
Use a soft cloth and mild soap with lukewarm water. Avoid harsh chemicals or abrasive cleaners as they can damage the helmet's finish and materials. Rinse thoroughly and air dry.
6.2. Cleaning the Interior Pads
The moisture-wicking, quick-drying liner features removable and washable cheek and crown pads. Gently detach the pads from the helmet. Hand wash them with mild soap and water, then air dry completely before reinserting. Ensure they are fully dry to prevent mildew.
6.3. Shield Replacement (HJ-17)
The RapidFire Shield Replacement System allows for fast, tool-free shield changes. Consult the helmet's quick-start guide or the HJC website for detailed instructions on how to remove and install the HJ-17 shield. Optional shields (HJ-17 Anti Fog Shield, HJ-17 RST Mirrored Shield) are sold separately.
6.4. Sun Visor Maintenance
The integrated sun visor is anti-scratch coated. Clean it with a soft, damp cloth. Do not use abrasive materials or strong cleaning agents.
7. Solució De Problemes
- Visor Fogging: Ensure vents are open for maximum airflow. Consider installing an optional Pinlock anti-fog insert for enhanced clarity.
- Ajust inadequat: Interchangeable cheek pads across all sizes offer a customized fit. If the helmet feels too loose or too tight, consult a certified HJC dealer for alternative pad sizes.
- Chin Bar Not Latching: Check for any obstructions. Ensure the release mechanism is not stuck. If the issue persists, do not use the helmet and contact HJC support.
- Problemes de connectivitat Bluetooth: Refer to the Smart HJC Bluetooth system's specific manual for pairing and troubleshooting steps.
8. Especificacions
| Característica | Detall |
|---|---|
| Marca | HJC |
| Nom del model | C91 |
| Tipus de closca | Hard, Advanced Polycarbonate Composite |
| Classificació de seguretat | DOT Certified (FMVSS 218) |
| Visera | HJ-17 Pinlock Shield (99% UV protection), Integrated HJ-V5 Sun Visor |
| Interior | Moisture-wicking, removable & washable pads, glasses grooves |
| Ventilació | Advanced Channeling Ventilation System (ACS) |
| Bluetooth llest | Smart HJC 10B or 20B (sold separately) |
| Pes de l'article | 3.46 lliures |
| Dimensions del producte | 13 x 12 x 16 polzades |
| Número de peça del fabricant | 0847-0135-11 |
| UPC | 190501178879 |
9. Què hi ha a la caixa
- C91 Solid Modular Motorcycle Helmet
10. Garantia i Suport
For warranty information, technical support, or to purchase replacement parts and accessories, please visit the official HJC website or contact your authorized HJC dealer. Always use genuine HJC replacement parts to maintain helmet integrity and safety standards.





