Yamaha YZ125H2 2017 Owner's Manual
![Yamaha YZ125H2 2017 manual cover](/images/560910001403154758d4fd4e/thumbs/thumb175x175.webp)
To properly break in the engine, start by running the engine at varying speeds for the first 30 minutes, avoiding full throttle. After the initial 30 minutes, ride for an additional hour at moderate speeds, gradually increasing throttle application. It's crucial to change the transmission oil after the break-in period to remove any metal particles.
The recommended maintenance schedule includes checking and cleaning the air filter every ride, changing transmission oil every 10 hours of riding, inspecting the spark plug every 6 hours, and lubricating the chain every ride. Regularly inspect and tighten bolts, nuts, and spokes as part of routine maintenance.
To adjust the carburetor, first locate the air screw and the idle screw. Adjust the air screw by turning it 1-2 turns out from fully seated, then adjust the idle screw to achieve a steady idle. Fine-tune the air screw by turning it in or out to find the smoothest idle. Test under load and readjust as necessary.
To clean the air filter, remove it from the air box and wash it in warm, soapy water. Rinse thoroughly and let it dry completely. Once dry, apply air filter oil evenly and squeeze out any excess. Reinstall the filter ensuring it's properly seated to avoid dirt ingress.
If the bike is difficult to start, check the spark plug for fouling and clean or replace it if necessary. Ensure there is sufficient fuel and that the fuel is not stale. Inspect the carburetor for blockages and clean it if necessary. Verify that the choke is functioning correctly.
The recommended tire pressure for the Yamaha YZ125H2 is typically around 12-15 psi for the front tire and 12-15 psi for the rear tire. Adjust the pressure based on the type of terrain and rider preference, ensuring not to go below 11 psi to avoid pinch flats.
Regularly inspect the suspension for leaks or damage. Clean the fork tubes after each ride to prevent dirt from entering the seals. Check and adjust the sag as needed, and consider having the forks and shock serviced by a professional every 40 hours of riding.
For the Yamaha YZ125H2, use a high-quality, motorcycle-specific 2-stroke transmission oil with a viscosity of 10W-40 or 10W-30. Ensure the oil meets or exceeds JASO MA or API SG specifications for optimal performance and protection.
To adjust the chain tension, place the bike on a stand and locate the chain adjusters on the swingarm. Loosen the axle nut, then turn the adjuster bolts evenly on both sides to achieve 30-40mm of slack at the midpoint of the chain. Tighten the axle nut securely once adjusted.
If the bike is overheating, check the coolant level and top it off if necessary. Ensure the radiator is free from obstructions and dirt. Examine the radiator cap for proper sealing and check the water pump for functionality. Avoid prolonged idling and ensure the fuel mixture is not too lean.