The Yamaha Grizzly 660, a popular ATV known for its reliability and power, requires regular maintenance to ensure optimal performance. One crucial aspect of this maintenance is valve lash adjustment. Improper valve lash can lead to decreased engine performance, reduced fuel efficiency, and even engine damage. This guide will walk you through the process of checking and adjusting valve lash on your 2003 Yamaha Grizzly 660, and address common questions surrounding this procedure. Remember to always consult your owner's manual for specific torque specifications and safety precautions.
Why is Valve Lash Adjustment Important?
Valve lash, also known as valve clearance, refers to the small gap between the valve stem and the rocker arm. This gap is necessary to allow for thermal expansion of the valve and prevent damage. Over time, wear and tear can cause this gap to change, leading to several problems:
- Decreased Engine Performance: Incorrect valve lash can prevent the valves from opening or closing completely, reducing engine power and responsiveness.
- Reduced Fuel Efficiency: Inefficient valve operation can lead to incomplete combustion, wasting fuel.
- Engine Damage: Excessive valve lash can cause the valves to float (not close completely), potentially damaging the engine. Insufficient lash can lead to bent valves.
Regular valve lash checks and adjustments are essential to maintaining your Grizzly 660's performance and longevity.
What Tools Will I Need?
Before you begin, gather the necessary tools:
- Yamaha Grizzly 660 Service Manual: This is crucial for specific torque specifications and diagrams.
- Valve Lash Feelers (Feeler Gauges): These are essential for measuring the valve clearance.
- Socket Wrench Set: You'll need various sockets to remove the valve cover and other components.
- Screwdrivers: Phillips and flathead screwdrivers may be necessary.
- Wrench Set: For various bolts and nuts.
- Clean Rags: To keep things clean and prevent debris from entering the engine.
- Safety Glasses: Protect your eyes.
- Gloves: Protect your hands.
How Often Should I Check My Valve Lash?
Yamaha recommends checking valve lash at regular intervals, typically every [Insert Recommended Interval from Service Manual – e.g., 5000 miles or 6 months]. However, if you notice any performance issues like decreased power or rough running, it's wise to check them sooner.
How to Check and Adjust Valve Lash on a 2003 Yamaha Grizzly 660
This procedure requires careful attention to detail. Refer to your service manual for detailed diagrams and torque specifications specific to your model year. This is a general overview and may not cover every nuance.
- Prepare the ATV: Ensure the engine is cold. Disconnect the battery negative terminal for safety.
- Remove the Valve Cover: Remove the valve cover bolts and carefully remove the cover. Clean any debris from the valve train.
- Locate the Valve Adjustment Screws: Identify the adjustment screws for both intake and exhaust valves.
- Set the Engine to TDC (Top Dead Center): Use your service manual to determine the proper piston position for valve adjustment. This is crucial for accurate measurements.
- Measure Valve Lash: Use the feeler gauges to measure the existing valve lash. Compare this to the specifications in your service manual.
- Adjust Valve Lash (if necessary): If the lash is outside the specified range, carefully adjust the locknuts and screws to achieve the correct clearance. Tighten the locknuts securely after adjustment.
- Reassemble: Carefully reinstall the valve cover and tighten the bolts to the specified torque.
- Reconnect the Battery: Reconnect the negative battery terminal.
- Start the ATV: Start the ATV and check for any unusual noises or performance issues.
What are the Symptoms of Incorrect Valve Lash?
What are the symptoms of loose valve lash?
Loose valve lash can manifest in several ways, including a ticking or tapping noise from the engine, reduced engine power, and rough idling. In extreme cases, it can lead to valve float and more serious engine damage.
What are the symptoms of tight valve lash?
Conversely, tight valve lash can also result in a ticking sound, but it might be accompanied by a lack of power, especially at higher RPMs. The engine might also struggle to start or idle properly.
How do I know if my valves need adjusting?
The best way to determine if your valves need adjusting is to perform the procedure outlined above and check the valve lash against the manufacturer's specifications. Listen carefully for unusual noises from the engine; any ticking or tapping sounds could indicate a problem.
Conclusion
Regular valve lash adjustment is essential for maintaining the performance and longevity of your 2003 Yamaha Grizzly 660. While this process may seem daunting, with careful attention to detail and the proper tools, you can perform this maintenance task yourself. Always refer to your service manual for specific instructions and torque specifications. If you are not comfortable performing this task, it’s best to consult a qualified mechanic. Remember safety first!
