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 adjusting the valve lash. This seemingly simple task is vital for preventing engine damage and maintaining peak efficiency. This guide will walk you through the process of checking and adjusting valve lash on your 2003 (and similar year models, 2000-2008) Yamaha Grizzly 660. We'll address common questions and concerns along the way.
What is Valve Lash?
Valve lash, also known as valve clearance, refers to the small gap between the valve stem and the rocker arm (or tappet) when the valve is closed. This gap is necessary to allow for thermal expansion of the valve and its components. Too much lash leads to noisy operation and reduced performance, while too little lash can cause the valves to remain slightly open, leading to bent valves or piston damage.
How Often Should I Check My Grizzly 660's Valve Lash?
Yamaha recommends checking valve lash at specified intervals in your owner's manual. However, a general guideline is to check it every 6 months or 500 operating hours. This depends on your riding conditions and how hard you run the engine. More demanding use might necessitate more frequent checks.
What Tools Do I Need to Adjust Valve Lash on a 2003 Yamaha Grizzly 660?
Before you begin, gather the necessary tools. This usually includes:
- Yamaha Grizzly 660 Service Manual: This is your bible for this job. It contains precise specifications and diagrams.
- Socket Set: Various sizes to remove the valve cover and other components.
- Wrench Set: Again, various sizes, likely including metric sizes.
- Feeler Gauges: Essential for measuring the valve lash.
- Torque Wrench: To ensure proper tightening of bolts.
- Shop Rags: To keep the engine clean.
- Valve Lash Adjusting Shims (if needed): These are crucial if adjustment is required. You'll need to know the correct shim size based on your measurements.
How to Check and Adjust Valve Lash on a Yamaha Grizzly 660
This process can be complex and varies slightly depending on the specific year and model. Always consult your service manual for detailed instructions specific to your ATV. These are general steps; specifics can vary:
- Prepare the ATV: Disconnect the battery.
- Remove the Valve Cover: Carefully remove the valve cover, noting the location of all components for easy reassembly.
- Locate the Valves and Rocker Arms: Identify the intake and exhaust valves.
- Rotate the Engine: Use the appropriate tool to rotate the crankshaft until you reach the required valve positions specified in your service manual. This ensures the valves are properly seated.
- Measure the Valve Lash: Use feeler gauges to measure the gap between the valve stem and rocker arm for both intake and exhaust valves. Your service manual will specify the correct clearance (lash) measurement for your 2003 Grizzly 660.
- Adjust the Valve Lash (if necessary): If the lash is outside the specified range, you'll need to replace the shims with the correct thickness to achieve the correct clearance. This often involves removing the rocker arms. Again, your service manual will provide detailed instructions on this.
- Reassemble: Carefully reassemble the valve cover and other components, ensuring everything is properly tightened to the torque specifications listed in the service manual.
- Reconnect the Battery: Reconnect the battery and start the engine to verify proper operation.
What Happens if I Don't Adjust My Grizzly 660's Valve Lash?
Neglecting valve lash adjustment can lead to several issues:
- Reduced engine performance: The engine won't run at peak efficiency.
- Engine noise: The engine will become noisy due to improper valve operation.
- Valve damage: Valves could bend or be damaged, potentially requiring more extensive repairs.
- Premature engine wear: Incorrect valve lash contributes to overall engine wear and tear.
Are there any common problems when adjusting valve lash on a Yamaha Grizzly 660?
Yes, common issues include:
- Difficulty finding the correct size shims: Finding the exact shim thickness can require ordering parts and waiting for delivery.
- Incorrect torque settings: Improper tightening of bolts can damage the engine.
- Misalignment of components: Careless reassembly can lead to misaligned parts and further issues.
Can I adjust the valve lash myself, or should I take it to a mechanic?
While this task is possible for mechanically inclined individuals, it requires precision and attention to detail. If you lack the experience or proper tools, it's best to take your Grizzly 660 to a qualified mechanic to avoid potential engine damage.
This guide provides a general overview. Always consult your Yamaha Grizzly 660 service manual for precise instructions and specifications relevant to your ATV's year and model. Remember, safety first! If you're unsure about any step, seek professional help.
