The Yamaha Grizzly 660, produced from 2002-2008, is a reliable ATV, but proper maintenance is crucial for optimal performance and longevity. One critical aspect of this maintenance is regular valve lash adjustment. Neglecting this can lead to decreased engine performance, reduced fuel efficiency, and even potential engine damage. This guide will walk you through the process of checking and adjusting valve lash on your 2003 Yamaha Grizzly 660 (the process is largely the same for the 2000-2008 models).
Understanding Valve Lash
Before we dive into the adjustment procedure, let's clarify what valve lash is. 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 engine components. If the lash is too tight (too little clearance), the valves can't fully close, leading to burned valves. Conversely, if the lash is too loose (too much clearance), the valves won't open fully, resulting in poor combustion and power loss.
Tools You'll Need
Before beginning, gather the necessary tools. Having everything prepared beforehand makes the process much smoother:
- Yamaha Grizzly 660 Service Manual: This is invaluable for detailed diagrams and torque specifications.
- Feeler Gauges: These are essential for measuring the valve lash. You'll need gauges in the correct sizes specified in your service manual.
- Socket Set: A variety of sockets and wrenches will be required to remove engine covers and other components.
- Torque Wrench: Crucial for tightening bolts to the correct specifications to prevent damage.
- Valve Adjustment Shims (if needed): These are used to adjust the valve lash if it's outside the specified range. You will likely need to order these beforehand, as they are specific to the Grizzly 660.
- Clean rags: To keep your work area clean.
- Safety Glasses: Always protect your eyes.
How to Check and Adjust Valve Lash on Your Yamaha Grizzly 660
This process requires careful attention to detail. Refer to your service manual for precise torque specifications and diagrams. This guide provides a general overview.
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Preparation: Begin by disconnecting the battery and allowing the engine to cool completely. Refer to your service manual for specific instructions on draining the coolant, if necessary.
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Access the Valve Cover: Remove the valve cover and any other components that obstruct access to the valves. Consult your service manual for the specific removal procedure.
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Locate the Valves: Identify the intake and exhaust valves. Your service manual will have diagrams showing the valve location and arrangement.
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Measure Valve Lash: Using your feeler gauges, carefully measure the valve lash for each valve. Compare your measurements to the specifications provided in your service manual.
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Adjust Valve Lash (if necessary): If the valve lash is outside the specified range, you will need to adjust it. This typically involves replacing the valve shims with ones of a different thickness to achieve the correct clearance. This is the most crucial step and requires careful attention to the procedure outlined in your service manual. Incorrect shim selection can lead to serious engine problems.
Frequently Asked Questions (FAQs)
Here are some common questions regarding valve lash adjustment on the Yamaha Grizzly 660:
How often should I check my valve lash?
The recommended frequency for checking valve lash varies, but it's generally advisable to do it every 6 months or 6,000 miles, whichever comes first. Always consult your owner's manual for the manufacturer's recommendation.
What happens if I don't adjust my valve lash?
Neglecting valve lash adjustment can lead to a variety of issues, including decreased engine performance, reduced fuel efficiency, noisy valves, and potential engine damage. In extreme cases, you could burn a valve.
Can I adjust the valve lash myself?
While it's possible, adjusting valve lash requires mechanical aptitude and careful attention to detail. If you're not comfortable working on your engine, it’s best to take your ATV to a qualified mechanic. Incorrect adjustment can cause serious engine damage.
Where can I find the correct valve shims?
Your local Yamaha dealer is the best place to source the correct shims for your Grizzly 660.
Conclusion
Regular valve lash adjustment is a critical part of maintaining your Yamaha Grizzly 660. While it requires some mechanical skills and attention to detail, the process is manageable for those with experience. Always refer to your service manual for specific instructions and torque specifications. If you are unsure about any part of this process, seek the assistance of a qualified mechanic. Remember, proper maintenance is key to enjoying years of reliable service from your ATV.
