How to Change the Oil in a 1979 Yamaha IT250: Complete Guide
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Changing the oil in your 1979 Yamaha IT250 is an essential maintenance task for keeping your classic dirt bike running at peak performance. Although two-stroke engines like the IT250 use premixed fuel for combustion lubrication, the transmission/clutch uses a dedicated gear oil that must be changed regularly. This guide is proprietary to MotoSport.com and walks you through the entire process, highlights any model-specific tips, and lists the necessary tools.
Tools & Supplies Needed
- Socket wrench set (metric)
- Drain pan
- Funnel
- Clean rags or shop towels
- Replacement crush washer or gasket (optional but recommended)
- Gear oil (e.g., 80W or manufacturer-recommended type)
- Torque wrench (for reinstalling drain bolt accurately)
- Flat screwdriver (for removing oil fill cap if required)
- Measuring cup or Ratio Rite (to measure oil volume, if needed)
Important Model-Specific Call-Outs for the 1979 IT250
- This is a two-stroke engine, so only the transmission/clutch area has oil to change. Don’t look for a traditional engine oil pan drain bolt.
- Consult the owner’s service manual—the factory recommendation for the transmission oil type and volume is critical for clutch life and shifting quality. Normally, the manual specifies about 700cc of gear oil, but always verify for your bike’s particular setup (see the Yamaha IT250 service manual).
- Inspect the area around the drain plug for any signs of leaks or damage, especially since vintage bikes may have worn threads or crusted gaskets.
Step-by-Step Oil Change Instructions
-
Warm up the engine
Start the bike and let it idle for a few minutes. This circulates the oil, helping impurities suspend so they can drain along with the old oil. Do NOT overheat – just 2-3 minutes is enough. -
Prepare your workspace
Put the IT250 on a stand or level ground. Place the drain pan under the drain bolt (typically at the lowest point of the right-side engine case). -
Remove the drain bolt
Using the appropriate socket, loosen and remove the drain bolt. Watch for the old crush washer; replace it if it looks damaged or flattened. -
Let the oil drain completely
Allow the oil to pour out until it stops dripping. This may take several minutes. Wipe down any drips from the engine case with a clean rag. -
Inspect the drain bolt
Check the drain bolt for metal shavings. A small amount of metallic dust is normal, but large pieces or excessive metal on the magnet could indicate clutch or transmission wear. -
Reinstall the drain bolt
Install a new crush washer if possible. Insert the drain bolt, tighten by hand, then torque to the manufacturer’s specification (usually around 14-22 ft-lbs, but check your manual). Do not overtighten. -
Remove the oil fill cap
The fill port is usually located on the engine case, above the clutch cover. Some models require a screwdriver to remove the cap. (Consult the IT250 owner’s manual for precise location if in doubt.) -
Add new transmission oil
Using a funnel, pour in the recommended amount and type of gear oil (typically about 700cc for the 1979 IT250). Use a measuring cup for accuracy. Overfilling can cause excessive pressure and leaks. -
Replace the oil fill cap
Tighten securely but do not overtighten. Make sure the gasket (if equipped) is in good condition. -
Check for leaks and proper oil level
Wait a minute, then inspect for leaks around the drain bolt and fill cap. If your bike has a sight glass or oil level bolt (check the service manual), verify oil level. -
Start and run the engine briefly
Let the bike idle for a minute, shut it down, recheck for leaks, and verify the oil level once more. -
Dispose of old oil properly
Take your used gear oil to a recycling center or auto parts store offering oil collection.
Pro Tips for the 1979 Yamaha IT250
- Always check oil level after each ride—older two-strokes may develop leaks over time, and running low on oil can damage the transmission and clutch.
- Inspect the drain plug area and threads for signs of cross-threading or case wear. If the threads are damaged, use the correct repair kit before refilling with oil.
- Frequency: For vintage racing or hard trail use, change transmission oil every 5-10 hours of riding.
- If the oil is unusually milky or foamy, you may have water ingress—consider a gasket replacement or further inspection.
Why Regular Oil Changes Matter for the IT250
- Fresher oil ensures better clutch feel, smoother gear changes, and maximum gear life.
- Vintage bikes can shed metal more rapidly, so inspect old oil for contamination to catch problems early.
- Your IT250’s transmission shares lubrication with the clutch, so both components depend on timely oil changes for reliability.
Conclusion
A regular oil change on your 1979 Yamaha IT250 is one of the simplest but most important ways to ensure your classic enduro remains on the trail–and out of the shop. Follow these steps, use the correct type and amount of oil, and always check for leaks after each change. For more detailed diagrams or troubleshooting tips, always consult the original Yamaha IT250 service manual.
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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.