The Yamaha XJ900 Diversion, a reliable workhorse for many riders, offers a blend of comfort, practicality, and reasonable performance. However, like any machine, it's not without its quirks and potential issues. Understanding these common problems and knowing how to address them can save you time, money, and frustration, keeping your Diversion on the road where it belongs. Let's dive into the nitty-gritty of what can go wrong and how to keep your XJ900 running smoothly.

What Are the Most Common XJ900 Diversion Issues?

While the XJ900 Diversion boasts a reputation for reliability, a few recurring issues tend to crop up, especially on older models. Addressing these proactively can prevent more serious problems down the line.

  • Carburetor Issues: This is arguably the most frequent complaint. Due to the age of many XJ900 Diversions, carburetors can become gummed up with old fuel, leading to poor running, difficulty starting, and uneven idling.
  • Charging System Problems: Regulators and rectifiers are known weak points, leading to battery drain and starting difficulties.
  • Exhaust System Corrosion: The original exhaust system is prone to rusting, particularly the downpipes and collector box.
  • Front Fork Stiction: Older models can suffer from stiction in the front forks, leading to a harsh ride.
  • Clutch Problems: Clutch slip can occur, especially under heavy load, due to worn friction plates or weakened springs.

Carburetor Conundrums: Why is My XJ900 Running Rough?

Let's face it, carburetors are complex beasts, and the XJ900's are no exception. Over time, varnish and deposits can build up in the jets and passages, disrupting fuel flow. This is especially true if the bike has been sitting for extended periods.

  • Symptoms of Carburetor Issues:
    • Difficulty starting, especially when cold.
    • Rough idling or stalling.
    • Hesitation or flat spots during acceleration.
    • Poor fuel economy.
    • Black smoke from the exhaust (indicating a rich mixture).
  • Troubleshooting Steps:
    1. Check the fuel: Ensure you're using fresh fuel and that there's no water contamination.
    2. Inspect the fuel filter: A clogged fuel filter can restrict fuel flow to the carburetors.
    3. Clean the carburetors: This is often the most effective solution. You can try using a carburetor cleaner additive, but a thorough disassembly and cleaning is usually necessary for heavily gummed-up carbs. Pay close attention to the jets, needles, and float bowls.
    4. Check the float levels: Incorrect float levels can cause rich or lean running conditions. Refer to the service manual for the correct specifications.
    5. Balance the carburetors: After cleaning and reassembling the carburetors, it's essential to synchronize them to ensure smooth running and optimal performance. This requires a set of vacuum gauges.
  • Pro Tip: When cleaning carburetors, use compressed air to blow out all the passages. Be careful not to damage any of the delicate parts. A carburetor rebuild kit, which includes new gaskets and O-rings, is a worthwhile investment.

Charging System Woes: Is My Battery Always Flat?

A healthy charging system is crucial for keeping your XJ900 running. The regulator/rectifier is a common culprit when things go wrong. This component is responsible for converting AC voltage from the alternator to DC voltage to charge the battery and regulate the voltage to prevent overcharging.

  • Symptoms of Charging System Problems:
    • Battery constantly going flat.
    • Difficulty starting.
    • Dim headlights.
    • Burning smell (from the regulator/rectifier).
  • Troubleshooting Steps:
    1. Check the battery voltage: A fully charged battery should read around 12.6 volts.
    2. Check the charging voltage: With the engine running at around 3000 RPM, the charging voltage should be between 13.5 and 14.5 volts.
    3. Test the regulator/rectifier: Use a multimeter to test the regulator/rectifier according to the service manual's instructions.
    4. Check the stator coils: The stator coils are located inside the alternator and generate the AC voltage. Test the resistance of the coils to ensure they are within specifications.
    5. Inspect the wiring: Look for any loose connections, corroded terminals, or damaged wires in the charging system.
  • Pro Tip: Consider upgrading to a MOSFET-type regulator/rectifier. These units are more reliable and run cooler than the original shunt-type regulators. Check online forums for recommended brands and models.

Exhaust System Erosion: Why is My Exhaust Rusted Through?

The original exhaust system on the XJ900 Diversion is made of mild steel and is susceptible to rust, especially in areas with harsh weather conditions or where salt is used on the roads.

  • Symptoms of Exhaust System Corrosion:
    • Visible rust on the exhaust pipes and collector box.
    • Exhaust leaks.
    • Increased engine noise.
    • Reduced performance.
  • Troubleshooting Steps:
    1. Inspect the exhaust system: Carefully examine the exhaust pipes, collector box, and silencer for any signs of rust or damage.
    2. Check for leaks: Start the engine and listen for any exhaust leaks. You can also use a soapy water solution to identify leaks.
  • Solutions:
    • Repair: Minor rust can be removed with a wire brush and treated with a rust converter. However, severely rusted sections may need to be replaced.
    • Replacement: Aftermarket stainless steel exhaust systems are available for the XJ900 Diversion and offer superior corrosion resistance.
    • Preventative Measures: Applying a heat-resistant paint or coating to the exhaust system can help protect it from rust. Regularly cleaning the exhaust system and removing any salt or road grime can also extend its lifespan.

Front Fork Frustration: Why is My Ride So Harsh?

Over time, the fork oil in the XJ900 Diversion's front forks can degrade, leading to stiction and a harsh ride. The seals can also harden and crack, causing leaks.

  • Symptoms of Front Fork Stiction:
    • Harsh ride over bumps.
    • Difficulty turning.
    • Front end feeling "stuck" or unresponsive.
    • Visible oil leaks from the fork seals.
  • Troubleshooting Steps:
    1. Inspect the fork tubes: Look for any signs of damage, such as dents or scratches.
    2. Check the fork seals: Examine the fork seals for any leaks.
    3. Test the fork action: Compress the front forks and release them. They should return smoothly and without any hesitation.
  • Solutions:
    • Fork Oil Change: Replacing the fork oil is a relatively simple and inexpensive way to improve the ride quality. Use the recommended fork oil weight and level specified in the service manual.
    • Fork Seal Replacement: If the fork seals are leaking, they need to be replaced. This requires removing the front forks and disassembling them.
    • Fork Rebuild: For severely worn forks, a complete rebuild may be necessary. This involves replacing the bushings, seals, and other internal components.
  • Pro Tip: Consider upgrading to progressive fork springs. These springs offer a more comfortable and controlled ride compared to the stock linear springs.

Clutch Catastrophes: Why is My Clutch Slipping?

Clutch slip is a common problem on older motorcycles, especially those that have been subjected to heavy use or abuse.

  • Symptoms of Clutch Slip:
    • Engine revs increasing without a corresponding increase in speed.
    • Difficulty accelerating, especially in higher gears.
    • Burning smell (from the clutch).
  • Troubleshooting Steps:
    1. Check the clutch cable adjustment: Ensure that the clutch cable has the correct amount of free play. Too little free play can cause the clutch to slip.
    2. Inspect the clutch friction plates: Remove the clutch cover and inspect the friction plates for wear. The friction material should be within the specified thickness.
    3. Check the clutch springs: Measure the length of the clutch springs to ensure they are within specifications. Weak springs can cause the clutch to slip.
  • Solutions:
    • Clutch Cable Adjustment: Adjust the clutch cable to ensure the correct amount of free play.
    • Clutch Friction Plate Replacement: Replace the worn friction plates with new ones.
    • Clutch Spring Replacement: Replace the clutch springs with new ones.
    • Clutch Basket Inspection: Ensure the clutch basket is not notched or grooved, which can prevent smooth clutch operation. File down any minor imperfections or replace the basket if severely damaged.

Frequently Asked Questions

  • Why is my XJ900 hard to start when it's cold?
    • This is often due to carburetor issues, such as clogged jets or incorrect fuel mixture. Ensure your choke is working properly and consider cleaning the carburetors.
  • My XJ900 is using a lot of fuel. What could be the cause?
    • Possible causes include a rich fuel mixture (due to carburetor problems), a clogged air filter, or a dragging brake. Check and address these issues to improve fuel economy.
  • How often should I change the oil on my XJ900 Diversion?
    • It's recommended to change the oil and filter every 3,000 miles or once a year, whichever comes first.
  • What type of oil should I use in my XJ900 Diversion?
    • Use a high-quality motorcycle-specific 10W-40 or 20W-50 oil that meets JASO MA or MA2 specifications.
  • Where can I find parts for my XJ900 Diversion?
    • Many online retailers specialize in motorcycle parts, and some local motorcycle shops may also carry parts for older models. eBay can also be a good source for used or NOS (new old stock) parts.

Keeping Your Diversion Alive and Kicking

The Yamaha XJ900 Diversion is a fantastic motorcycle that offers a rewarding riding experience. By understanding the common problems and taking proactive steps to address them, you can keep your Diversion running smoothly for years to come. Regular maintenance and attention to detail are key to preserving the life of your trusty steed.