How to Change the Oil in a 1987 Yamaha YZ80
Changing the oil in your 1987 Yamaha YZ80 is an essential maintenance task that keeps the engine and transmission running smoothly and extends the life of your dirt bike. While this job may seem daunting to some new owners, the YZ80's simple two-stroke, small-displacement engine makes the process straightforward. This model, produced during Yamaha's legendary late-’80s two-stroke lineup, lacks an oil filter and boasts easy access to the drain and fill plugs. This guide, created exclusively for MotoSport.com, provides all the steps, tips, and tools you need to change oil correctly and confidently on your 1987 YZ80.
Tools and Materials Needed
- 10mm socket or wrench (for drain plug removal)
- Drain pan (to catch old oil)
- Rag or shop towels
- New transmission oil (plain two-cycle gear oil, 500ml/0.5 quarts, see specifics below)
- Measuring cup (to accurately measure new oil)
- Copper washer or crush washer (optional, if your existing one is worn out or damaged)
- Socket extension (optional for hard-to-reach bolts)
- Funnel (optional, for easy pouring)
- Bike stand (to keep your YZ80 upright and level)
- Gloves (to keep your hands clean)
Step-by-Step Instructions for Oil Change
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Warm Up the Engine
Briefly start your YZ80 and let it idle for a few minutes. This helps the oil warm up and drain more thoroughly. Always make sure the engine is off and cool enough to touch before proceeding. -
Stabilize the Bike
Set the YZ80 on a bike stand or a level surface to ensure it stays upright and stable throughout the process. -
Locate the Drain Plug
The drain plug on a 1987 YZ80 is located on the bottom center of the motor, in between the foot pegs, right under where it says "Yamaha". For these models, it’s often the middle bolt underneath the crankcase on the left side of the bike. There’s no oil filter to remove. -
Drain the Oil
Place your drain pan directly beneath the drain plug. Using a 10mm wrench or socket, carefully remove the drain bolt. Allow all old oil to drain fully. Be patient and tip the bike slightly from side to side if needed to ensure all oil exits the bottom of the case. -
Inspect and Replace Washer
Check the copper or crush washer on your drain plug for cracks or deformation. Replace if necessary to prevent leaks upon reinstalling. -
Clean and Reinstall Drain Plug
Wipe the drain plug and its seating surface clean. Hand-thread the bolt back into the drain hole, then use the wrench to tighten. Do not overtighten, as this can strip the threads in the relatively soft aluminum case. -
Fill with Fresh Oil
Remove the oil fill cap (usually located on the left engine case cover). Using a measuring cup, pour in 500ml (about 0.5 quarts) of fresh two-stroke transmission oil. Use a funnel to avoid spills. -
Check the Oil Level
Some YZ80s have a sight glass to confirm the oil level. If not, measure carefully. The correct level ensures proper clutch and transmission function. Replace the fill cap and ensure it is tight. -
Wipe Up Any Spills
Use rags or towels to clean up excess oil that may have dripped on the cases or floor. -
Dispose of Old Oil Responsibly
Pour the old oil into a sealed container and recycle at your local auto parts store or disposal facility.
1987 Yamaha YZ80 Model-Specific Call-Outs
- No Oil Filter: The YZ80 does not have an oil filter—no need to replace or clean one during each oil change.
- Oil Capacity: The correct capacity is 500ml (0.5 quart) of plain two-stroke gear oil. Do not overfill, as it can cause clutch slippage or oil weeping.
- Drain Plug Location: This plug is more central on the case bottom than on some newer models. Double-check you’re removing the correct bolt (middle and right under the crankcase labeled “Yamaha”).
- No Dipstick: There is no dipstick. Some bikes have a sight glass, but many do not, so measuring oil quantity is critical. Double-check your owner’s manual if in doubt.
- Tightening Torque: Always tighten the drain bolt just enough to compress the crush washer but avoid overtightening—you risk damaging the soft aluminum threads.
- Premix System: The 1987 YZ80 runs premix fuel, so this oil change only addresses the transmission and clutch oil, not any injectors or oil tanks.
Common Questions and Tips
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What type of oil should I use?
Use a high-quality two-stroke transmission or gear oil (non-engine oil) specifically formulated for dirt bikes. Synthetic options are available for better protection under racing conditions. -
How often should I change the oil?
For motocross use, after every 8-10 hours of riding or after every few rides in aggressive conditions. If the bike is used rarely or for light trail riding, every 3-4 months is adequate. -
Can I change the oil without a stand?
Yes, but stabilizing the bike is safer and allows for a more complete drain.
Final Thoughts
Changing the oil on a 1987 Yamaha YZ80 is a straightforward process that takes minimal time and can save significant money on long-term repairs. Always use the correct oil type and quantity. If you notice metal shavings, milky oil (water contamination), or excessive debris during the change, consult a mechanic, as these are signs of deeper issues.
For all your OEM and aftermarket dirt bike maintenance parts, trust MotoSport.com to supply the tools, lubricants, and expert advice you need to keep your YZ80 at its best.
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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.