The Yamaha Diversion 900, also known as the Seca II in some markets, is a motorcycle celebrated for its reliability and practicality. However, like any machine, it's not immune to issues. Understanding the common problems that can plague these bikes is crucial for owners, both prospective and current, ensuring they can enjoy the Diversion 900's strengths without being blindsided by potential weaknesses. This article dives into the most frequently reported issues, offering insights and potential solutions to keep your Diversion 900 running smoothly.

What's That Funny Noise? Common Engine Issues

The heart of the Diversion 900, its inline-four engine, is generally robust, but certain issues can arise over time. These are often related to wear and tear, maintenance neglect, or the age of the motorcycle.

  • Valve Clearances: This is probably the most common issue, especially on bikes that haven't had regular servicing. Over time, valve clearances can tighten, leading to poor running, difficult starting, and even engine damage if left unchecked. Regular valve clearance checks (typically every 6,000 miles) are essential. Listen for a "ticking" sound that gets louder as the engine warms up – this can be a sign of tight valve clearances.
  • Carburetor Problems: Being an older bike, the Diversion 900 relies on carburetors, which can suffer from various issues. Gumming up due to old fuel is a frequent culprit, leading to poor idling, hesitation, and flat spots in the power delivery. A thorough carburetor cleaning and rebuild, including replacing jets and diaphragms, can often solve these problems. Balancing the carburetors after cleaning is also critical.
  • Cam Chain Tensioner (CCT) Issues: The cam chain tensioner keeps the cam chain taut, preventing it from rattling and potentially jumping teeth. The original CCT design on some Diversion 900s can be prone to failure. Symptoms include a rattling noise, particularly on startup. Many owners opt to replace the original CCT with a manual adjuster for increased reliability.
  • Oil Leaks: Older bikes often develop oil leaks, and the Diversion 900 is no exception. Common leak points include the valve cover gasket, the oil pan gasket, and around the crankshaft seals. While some leaks are minor and can be tolerated, significant leaks should be addressed to prevent engine damage and maintain proper oil levels.
  • Starter Motor Problems: A sluggish or non-functioning starter motor can be frustrating. Common causes include worn brushes, a faulty solenoid, or poor electrical connections. Cleaning and lubricating the starter motor components, or replacing worn parts, can often resolve the issue.

Electrical Gremlins: Tracing the Wires

Electrical issues can be tricky to diagnose, but they're a common source of frustration for Diversion 900 owners.

  • Charging System Failures: A weak or failing charging system can lead to a dead battery and a bike that won't start. The most common culprits are the stator, the rectifier/regulator, and the battery itself. Testing each component with a multimeter is essential to pinpoint the source of the problem. Upgrading the rectifier/regulator to a modern MOSFET unit can improve reliability.
  • Wiring Harness Issues: Over time, the wiring harness can become brittle and corroded, leading to intermittent electrical problems. Check for frayed wires, loose connections, and corrosion, particularly in areas exposed to the elements. Applying dielectric grease to electrical connectors can help prevent corrosion.
  • Ignition System Problems: Issues with the ignition system, such as faulty ignition coils or a failing ignition control module (ICM), can cause misfires, poor running, and difficulty starting. Testing the ignition components with a multimeter and replacing any faulty parts is necessary.
  • Fuse Problems: Blown fuses are often a symptom of a larger electrical problem. Always replace a blown fuse with one of the correct amperage rating. If the fuse blows repeatedly, investigate the circuit for shorts or other issues.
  • Instrument Panel Issues: The instrument panel can suffer from problems such as dim or non-functional lights, or inaccurate readings. Check the wiring connections and bulbs first. If the problem persists, the instrument panel itself may need to be repaired or replaced.

Suspension and Handling Woes: Keeping it Stable

The Diversion 900's suspension and handling are generally good, but age and wear can take their toll.

  • Worn Suspension Components: Over time, the fork seals can leak, the fork oil can degrade, and the rear shock can lose its damping ability. These issues can lead to poor handling, a bouncy ride, and reduced braking performance. Replacing the fork seals and oil, and rebuilding or replacing the rear shock, can significantly improve the bike's handling.
  • Steering Head Bearings: Worn steering head bearings can cause a "notchy" or "sticky" feeling in the steering, particularly at low speeds. Replacing the steering head bearings is necessary to restore smooth and predictable steering.
  • Wheel Bearings: Worn wheel bearings can cause a rumbling noise and can affect handling. Check the wheel bearings for play and replace them if necessary.
  • Tire Condition: Always ensure your tires are in good condition and properly inflated. Worn or improperly inflated tires can significantly affect handling and braking performance.

Braking Blues: Ensuring Safe Stops

Reliable brakes are essential for safety. Here are some common braking issues on the Diversion 900:

  • Sticking Calipers: Over time, the brake calipers can become corroded and the pistons can stick, leading to uneven braking and reduced braking performance. Cleaning and lubricating the calipers and pistons can often resolve the issue. Replacing the brake seals may also be necessary.
  • Worn Brake Pads and Rotors: Worn brake pads and rotors will reduce braking performance. Inspect the brake pads and rotors regularly and replace them when they reach their wear limits.
  • Brake Fluid Contamination: Brake fluid absorbs moisture over time, which can lead to corrosion and reduced braking performance. Bleeding the brakes and replacing the brake fluid every two years is essential.
  • Master Cylinder Problems: A faulty master cylinder can cause a spongy brake feel and reduced braking performance. Rebuilding or replacing the master cylinder may be necessary.

Bodywork and Aesthetics: Keeping it Looking Good

While not directly affecting performance, maintaining the bodywork and aesthetics of your Diversion 900 is important for pride of ownership.

  • Cracked or Damaged Fairings: The fairings can be prone to cracking or damage, particularly in accidents. Repairing or replacing the fairings can be costly, but it can significantly improve the bike's appearance.
  • Rust: Rust can be a problem, particularly on bikes that have been exposed to the elements. Addressing rust early can prevent it from spreading and causing further damage.
  • Faded Paint: The paint can fade over time, particularly on bikes that have been exposed to the sun. Polishing and waxing the paint can help restore its shine.

Frequently Asked Questions

  • Why does my Diversion 900 idle poorly? Carburetor issues, such as gummed-up jets or incorrect idle settings, are the most common cause. A thorough carburetor cleaning and adjustment are usually required.
  • My battery keeps dying. What could be the problem? A failing charging system, a parasitic drain, or a bad battery are the most likely causes. Test the charging system components and check for any excessive current draw when the bike is off.
  • Why is my front suspension so soft? Worn fork oil, leaky fork seals, or weak fork springs are the usual culprits. Replacing the fork oil and seals, and potentially upgrading the fork springs, will improve the suspension.
  • How often should I change the oil? Yamaha recommends changing the oil every 6,000 miles or annually, whichever comes first. Using a high-quality motorcycle-specific oil is recommended.
  • What is the best way to store my Diversion 900 for the winter? Stabilize the fuel, change the oil, disconnect the battery, and store the bike in a dry, covered location. Using a battery tender is also a good idea.

Conclusion

The Yamaha Diversion 900 is a capable and reliable motorcycle, but like any machine, it requires regular maintenance and attention to potential problems. By understanding the common issues outlined in this article and addressing them promptly, you can keep your Diversion 900 running smoothly and enjoy many more miles of riding. Don't hesitate to consult a qualified motorcycle mechanic if you're unsure about any repairs or maintenance procedures.