How to Change the Transmission Oil in a 1987 Suzuki JR50

Shop parts for a 1987 Suzuki JR50 Dirt Bike.

Changing the transmission oil in your 1987 Suzuki JR50 is crucial for maintaining smooth operation and prolonging the life of your dirt bike's internal components. This maintenance procedure is straightforward and can be handled at home with basic tools and supplies. Below is a detailed, proprietary guide exclusive to MotoSport.com to help you through the process, with specific notes for the JR50 model year.

Tools and Materials Needed

  • 10mm wrench or socket (for the oil drain plug and level screw)
  • Drain pan (to catch old oil)
  • Funnel (for adding new oil)
  • Clean shop rags (for spills and wiping parts)
  • Measuring cup (capable of measuring up to 500ml)
  • Replacement transmission oil (SAE type and grade as specified in your owner's manual – typically SAE 10W-30 or SAE 10W-40, non-friction-modified oil is recommended for wet clutches)
  • Gloves (recommended for handling used oil and preventing skin contact)
  • Proper container for recycling used oil

Step-by-Step Instructions

  1. Warm up the engine:
    Start the bike and let it idle for a few minutes. This warms the oil and helps it drain more completely and quickly. Always perform the oil change with the engine warm, not hot.
  2. Stabilize the motorcycle:
    Set the JR50 on level ground and secure it on its side stand. To ensure all oil drains, you'll hold the bike vertically during draining.
  3. Remove the oil filler cap:
    Locate and unscrew the oil filler cap on the side of the engine. This allows air in and helps the old oil drain faster.
  4. Remove the drain plug:
    Position your oil drain pan directly beneath the engine. Use the 10mm wrench or socket to remove the transmission oil drain plug from the bottom of the engine case. Let all oil drain completely while holding the motorcycle vertically.
  5. Inspect and replace the drain plug:
    After the oil is fully drained, inspect the drain plug and washer for damage or metal particles. Replace the drain plug and torque it snugly (do not overtighten).
  6. Remove the oil level screw:
    You'll find the oil level screw to one side of the engine. Remove it so you can be sure not to overfill.
  7. Add new transmission oil:
    Using your funnel and measuring cup, pour 450 ml (0.5 US qt) of the recommended oil into the filler hole. Add oil slowly until it comes out of the oil level hole (with bike held vertically).
  8. Check the oil level:
    When oil begins to seep from the oil level hole, the oil is at the correct level. Reinstall the oil level screw and torque gently.
  9. Reinstall the oil filler cap:
    Replace the oil filler cap and clean off any spilled oil.
  10. Recycle used oil:
    Carefully pour the used oil into a suitable container and take it to a recycling facility. Never dispose of oil in the trash or on the ground.

Important JR50 Model-Specific Call-Outs

  • The 1987 Suzuki JR50 shares its transmission oil capacity (450 ml or 0.5 US qt) with other production years, but always double-check your owner's manual for specifics.
  • The JR50 uses separate transmission oil; it is a two-stroke bike and does not use engine oil for its transmission. Don't confuse the oil tanks for pre-mix/oil injection (used for the combustion process) with the transmission (gearbox) oil system.
  • If your JR50 is equipped for oil injection (auto-lube), ensure the oil delivery system for the engine is maintained separately and not confused with transmission oil. Premix and injection systems deal only with the engine and never the gearbox, which always requires clean, dedicated gear oil as described.
  • The JR50's drain and level plugs are small and easy to strip; use the correct size tool, and never overtighten.
  • Replace any copper washers or O-rings on the drain and level screws if they appear worn or damaged, as a leaky seal can lead to rapid gearbox failure.
  • Run the engine briefly after filling and double-check for leaks at the plugs and level screw.

Final Tips

  • Change oil after the initial break-in (usually around 1 month or several hours of use), then every 6 months or as recommended by Suzuki.
  • Wear gloves as engine oil can be irritating and prolonged contact should be avoided.
  • Always verify and use the oil type and volume specified for the JR50–not all small dirt bikes use the same requirements.
  • If you ride or store your JR50 in very dusty or wet conditions, inspect and possibly change the transmission oil more frequently.

Proper oil changes will ensure your 1987 Suzuki JR50 transmission runs smooth so you can keep riding with confidence. Rely on MotoSport.com for all your JR50 parts and maintenance needs.

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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.