Yamaha YZ125S 2004 Owner's Manual

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Year 2004

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Yamaha YZ125S 2004 Specification

The Yamaha YZ125S 2004 is a high-performance motocross bike engineered for superior agility, speed, and control on the track. This model is powered by a 124cc, liquid-cooled, two-stroke engine that delivers robust power and rapid acceleration, essential for competitive racing. The engine features a reed valve induction system, enhancing throttle response and efficiency. It is paired with a six-speed transmission, allowing riders to seamlessly shift gears for optimal performance in various track conditions.

The bike's chassis is constructed from a lightweight aluminum frame, providing excellent strength-to-weight ratio. This contributes to the YZ125S's nimble handling and responsive maneuverability. The suspension system includes a fully adjustable, 46mm inverted fork at the front and a monocross rear suspension with a piggyback reservoir, ensuring a smooth ride and precise handling over rough terrain.

Braking is handled by a hydraulic disc brake system, with a 250mm disc at the front and a 245mm disc at the rear, offering reliable stopping power. The bike rolls on durable, lightweight rims fitted with knobby tires designed for maximum traction on dirt surfaces.

The ergonomics of the Yamaha YZ125S 2004 are tailored for rider comfort and control, featuring a slim, aggressive bodywork and a flat seat profile that allows for easy movement and better control. The fuel tank has a capacity of 8 liters, providing ample range for extended track sessions. Overall, the Yamaha YZ125S 2004 is a meticulously engineered motocross machine that combines powerful performance, precise handling, and rider-focused design, making it a formidable choice for serious motocross enthusiasts.

Yamaha YZ125S 2004 F.A.Q.

What is the recommended spark plug for the Yamaha YZ125S 2004?

The recommended spark plug for the Yamaha YZ125S 2004 is the NGK BR9EG. It is advisable to check and replace the spark plug regularly to maintain optimal engine performance.

How often should I change the transmission oil on a Yamaha YZ125S 2004?

It is recommended to change the transmission oil every 5-10 hours of riding or after every race. Use a high-quality 10W-40 or 10W-30 oil for best results.

What is the correct tire pressure for the Yamaha YZ125S 2004?

The recommended tire pressure is 12 psi for the front tire and 12 psi for the rear tire. Adjust the pressure based on track conditions and rider preference.

How do I troubleshoot a Yamaha YZ125S 2004 that won't start?

If your YZ125S won't start, check the following: ensure there is enough fuel, inspect the spark plug for fouling, verify the kill switch is in the "run" position, and check for any loose or damaged wires.

What is the correct chain tension for the Yamaha YZ125S 2004?

The correct chain tension should allow for 1.4 to 1.6 inches (35-40 mm) of slack at the midpoint between the front and rear sprockets. Regularly check and adjust to prevent premature wear.

How do I clean the air filter on a Yamaha YZ125S 2004?

Remove the air filter, wash it with soapy water, rinse thoroughly, let it dry completely, and then apply a thin layer of air filter oil before reinstalling. Clean it after every ride in dusty conditions.

What type of coolant should be used in the Yamaha YZ125S 2004?

Use a high-quality ethylene glycol-based coolant with anti-corrosion properties. Always mix with distilled water in a 50/50 ratio for optimal cooling performance.

How can I improve the suspension setup on my Yamaha YZ125S 2004 for better handling?

To improve handling, adjust the fork compression and rebound settings to your riding style and weight, and set the rear shock sag to approximately 100 mm. Experiment with settings until you find the optimal setup.

What is the correct procedure for adjusting the carburetor on a Yamaha YZ125S 2004?

Start by setting the pilot screw to the factory setting, then adjust the idle speed. Fine-tune the pilot screw for a smooth idle and crisp throttle response. Always make adjustments with a warm engine.

How often should I replace the brake pads on my Yamaha YZ125S 2004?

Brake pad replacement intervals depend on riding conditions and frequency. Inspect the pads regularly and replace them when the friction material is 1 mm thick or less to ensure optimal braking performance.