How to Change the Oil in a 2014 GAS GAS TXT RACING 300

Shop parts for a 2014 GAS GAS TXT RACING 300 Dirt Bike.

Regularly changing the transmission oil on your 2014 GAS GAS TXT RACING 300 is essential for maintaining optimal clutch performance and gearbox longevity. This step-by-step, proprietary MotoSport.com guide will ensure your oil change is effective, efficient, and prevents unnecessary wear on your trials bike’s transmission system.

Tools & Materials Needed

  • Socket set (typically 13mm for the drain bolt, but confirm size for your specific model before starting)
  • Torque wrench (recommended for proper reinstallation)
  • Drain pan
  • Rags or shop towels
  • Funnel
  • Replacement washer for the drain bolt (optional, but prevents leaks)
  • Quality gear/transmission oil – most GasGas TXT models use about 450-500ml of quality 75W gear oil or manufacturer-recommended equivalent
  • Gloves (optional yet recommended)

Preparation

  • Warm up the engine slightly to allow the oil to flow more easily, but shut it off before you begin. Place the bike upright on a stand for a level drain.
  • Wipe around the filler plug and drain bolt areas to remove any dirt that could contaminate the transmission when opened.

Step-by-Step Instructions

  1. Locate the Oil Drain Bolt
    • The drain bolt is usually at the bottom of the right side engine case. Reference the manual or check for a 13mm-headed bolt below the clutch cover.
  2. Remove the Drain Plug & Drain the Oil
    • Place a drain pan under the bolt, then gently loosen and remove the drain bolt, allowing the old oil to flow out completely.
    • Inspect the washer for wear; replace if deformed or overly compressed to prevent leaks upon reinstallation.
    • Let the oil drain entirely. Rock the bike side to side to help the last of the oil escape.
  3. Check and Clean the Drain Plug
    • Wipe the drain plug clean. Check for metallic particles on the magnet, which are common but should be minimal. Excessive metal may indicate gear wear.
  4. Reinstall the Drain Plug
    • Screw the cleaned or new washer and drain bolt back in by hand, then torque to the manufacturer’s spec (avoid overtightening to prevent stripping the threads)
  5. Refill with New Oil
    • Remove the filler cap, usually on the right side engine cover above the clutch.
    • Using a funnel, pour in the recommended quantity (about 450-500ml) of the specified gear oil. Double-check your owner’s manual for exact volume.
  6. Check Oil Level
    • Many trials bikes use a sight glass or level screw. If your TXT 300 has a level bolt (small bolt halfway up the case), remove it and add oil until it seeps slightly out, then reinstall the bolt.
    • If using a sight glass, ensure the oil is at the center of the window (with the bike upright and level).
  7. Final Checks and Cleanup
    • Wipe away any spilled oil from the engine and cases.
    • Reinstall the oil filler cap securely.
    • Run the engine for 1-2 minutes, then shut off and inspect the drain and filler areas for leaks.
    • Re-check the oil level and top off if necessary.

Model-Specific Call-Outs for 2014 GAS GAS TXT RACING 300

  • The 2014 TXT RACING 300 uses a simple transmission oil system—no oil filter is involved. The oil is separate from the two-stroke premix in the tank.
  • Ensure you do not overtighten the drain bolt. The casing is relatively soft, and excessive torque can strip threads easily; only use a torque wrench at the recommended specification.
  • A magnetic drain bolt is stock; clean off any collected fragments.
  • Some early TXT models had variability in oil sight glass manufacturing. If you do not see a sight glass, always refill gradually and use the level plug method to avoid overfilling.
  • The clutch action and gear shifting can be directly affected by oil condition—old or incorrectly filled oil can cause hard shifting or clutch drag.
  • Recommended oil change interval is every 20-30 hours of riding for optimal trials performance—not just the standard mileage-based interval listed in some manuals.
  • Do not substitute outboard gear oils or automotive engine oils. Use only manufacturer-recommended or high-quality motorcycle-specific gear oil for proper clutch operation.

Pro Tip: If you ride in wet or muddy conditions, decrease the interval between changes, as moisture and debris can intrude past the clutch cover gasket more easily on older trials bike designs.

By following these MotoSport.com instructions, your 2014 GAS GAS TXT RACING 300’s clutch and gearbox will run smoother, last longer, and provide confident performance with every ride.

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Disclaimer: This guide is provided for general informational purposes only and is not intended to replace your motorcycle's official owner's manual. Always refer to your manufacturer's documentation for model-specific instructions, torque specifications, safety procedures, and maintenance requirements. If you are unsure or inexperienced, consider seeking assistance from a qualified mechanic or technician.