KOSO Aluminum Thermostat B8R Engine Family

Upgraded Material – Aluminum Alloy
Replaces the original engineering plastic housing with a CNC-machined aluminum alloy version for enhanced durability and heat resistance.
Superior Durability
Aluminum construction offers higher thermal tolerance, resistance to cracking and aging, and excellent corrosion resistance when in long-term contact with coolant. Ensures long-lasting reliability in the cooling system.
Improved Heat Dissipation
Aluminum’s superior thermal conductivity allows for more efficient heat transfer compared to plastic, helping the engine maintain a stable operating temperature and reducing the risk of overheating.
Premium Appearance
Finished with a dual-tone high-gloss paint and precision CNC craftsmanship for a high-end, performance-inspired look.

Cold Start Phase
At low temperatures, the thermostat remains closed, preventing coolant from circulating through the radiator. This allows the engine to reach operating temperature quickly.
Warm-Up Phase
As the temperature rises, the thermostat gradually opens, controlling the coolant flow through the radiator to maintain a balanced engine temperature.
Stable Operating Phase
Once warmed up, the thermostat modulates coolant flow to keep the engine within the optimal temperature range of 70°C to 90°C, ensuring peak performance and longevity.

Applicable to YAMAHA B8R engine family 125~155cc

CYGNUS GRYPHUS
X-Force
Zuma 125
AUGUR
AEROX 2021
N-MAX 2020
N-MAX 2022
MADE IN TAIWAN