The Yamaha Grizzly 660, a popular ATV known for its reliability and power, requires regular maintenance to ensure optimal performance and longevity. One crucial aspect of this maintenance is valve lash adjustment. Incorrect 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 will also address some frequently asked questions.
Understanding Valve Lash
Valve lash, also known as valve clearance, refers to the small gap between the valve stem and the rocker arm when the valve is closed. This gap is necessary to allow for thermal expansion of the engine components. If the lash is too tight (too little clearance), the valves can't close completely, leading to poor performance. Conversely, if the lash is too loose (too much clearance), the valves may not open fully, also impacting performance. Regularly checking and adjusting valve lash is vital for maintaining your Grizzly 660's engine health.
Tools and Materials You'll Need
Before you begin, gather the necessary tools and materials:
- Yamaha Grizzly 660 Service Manual: This is your bible for this procedure. It contains detailed diagrams and specifications crucial for accurate adjustment.
- Feeler Gauges: A set of feeler gauges in the appropriate thicknesses is essential for accurately measuring valve lash.
- Sockets and Wrenches: You'll need the correct sockets and wrenches to remove and reinstall components, as specified in your service manual.
- Torque Wrench: To ensure proper tightening of the rocker arm bolts, preventing damage to the engine.
- Clean Rags: To keep the engine clean and prevent debris from entering.
- Safety Glasses: Protect your eyes from flying debris.
- Gloves: Protect your hands from grease and grime.
How to Check and Adjust Valve Lash on Your 2003 Yamaha Grizzly 660
This process is best done with the engine cold. The steps below provide a general overview. Always refer to your Yamaha Grizzly 660 service manual for specific instructions, torque specifications, and diagrams. Improper adjustment can cause serious engine damage.
- Prepare the ATV: Disconnect the battery, remove the fuel tank, and gain access to the valve cover. Your service manual will guide you through this.
- Remove the Valve Cover: Carefully remove the valve cover, taking note of the location and order of any components you remove.
- Locate the Rocker Arms: Identify the intake and exhaust rocker arms for each cylinder.
- Set the Engine to Top Dead Center (TDC): Use the crankshaft position to ensure the engine pistons are at the correct position for valve adjustment. Your service manual will guide you.
- Measure Valve Lash: Insert the appropriate feeler gauge between the valve stem and the rocker arm for each valve. Your service manual will specify the correct clearance measurements (usually expressed in millimeters).
- Adjust Valve Lash (If Necessary): If the lash is incorrect, adjust it by turning the adjusting nut on the rocker arm. You'll need to loosen the rocker arm locknut first. Re-check the lash after adjustment.
- Tighten Locknuts: Once the correct lash is achieved, carefully tighten the locknuts to the specifications in your service manual.
- Reassemble: Reinstall the valve cover, fuel tank, and connect the battery.
Frequently Asked Questions (FAQs)
Here are some common questions regarding valve lash adjustment on the Yamaha Grizzly 660:
How often should I check and adjust my Yamaha Grizzly 660's valve lash?
The recommended interval for checking and adjusting valve lash on a Yamaha Grizzly 660 is typically every 6,000-8,000 miles or once a year, whichever comes first. However, always refer to your owner's manual for the manufacturer's recommended schedule. Harsh riding conditions may require more frequent checks.
What happens if I don't adjust my valve lash?
Neglecting valve lash adjustment can lead to decreased engine performance, reduced fuel efficiency, burning valves, and ultimately, engine damage.
Can I adjust the valve lash myself, or should I take it to a mechanic?
While you can potentially do it yourself, it's a delicate procedure. If you're not comfortable working on engines, or if you don't have the necessary tools and experience, it's best to take your Grizzly 660 to a qualified mechanic. Incorrect adjustment can cause serious damage.
What are the symptoms of incorrect valve lash?
Symptoms of incorrect valve lash can include decreased engine performance, difficult starting, rough idling, loss of power, and unusual noises coming from the engine.
This guide provides a general overview of the valve lash adjustment process for the 2003 Yamaha Grizzly 660. Always consult your Yamaha Grizzly 660 service manual for detailed instructions and specifications specific to your model year. Remember, precision and care are essential when performing this maintenance task. If you are unsure about any step, it’s always best to seek professional help.
