Animated service guide
How to Change Dirt Bike Oil and the Oil Filter
A race four-stroke runs about a liter of oil through the crank, the valve train, the gearbox and the wet clutch. Clutch dust, heat and fuel wear it out fast, so the race manuals call for fresh oil every 7.5 to 15 hours depending on the brand. Trail schedules can read differently. Honda’s CRF450X non-competition schedule says every 600 miles (1,000 km) or 6 months, while KTM’s 450 XCF-W enduro still says 15 hours. Follow the one printed for your bike. This is the full drain, screen, filter and refill.
The animated guide loads here. Every step is also written out below.
Before You Start
Tools
- Socket set and a torque wrench
- Drain pan and funnel
- Lock ring pliers or a filter tool if your filter needs one
- Clean rags and parts cleaner
Parts And Supplies
- Engine oil of the grade your manual names (JASO MA)
- New oil filter
- New drain plug sealing washer and O-rings
Safety
- Drain it warm, not hot. Oil at operating temperature can scald, so wear gloves.
- Run the engine only outside or with good ventilation. Exhaust gas can kill.
- Take used oil and filters to a recycling point.
Step By Step
Know where your oil goes
On most race four-strokes one oil feeds the crank, the cam and valves, the gearbox and the wet clutch. That is why it has to be a JASO MA motorcycle oil, not car oil. The YZ450F keeps its oil in a separate tank, so it drains in two places.
Engine oil Bike Spec Source KTM / Husqvarna / GASGAS 4-stroke SAE 10W/50, JASO MA2 KTM 250 SX-F 2024 owner’s manual, PDF p. 163 (fully synthetic) Honda CRF250R / CRF450R SAE 10W-30, JASO MA Honda CRF250R 2025 owner’s manual, PDF p. 79 (not energy conserving) Yamaha YZ250F / YZ450F 10W-40 to 20W-50, MA Yamaha YZ250F 2026 owner’s service manual, PDF p. 104 (API SG or higher) Suzuki RM-Z250 / RM-Z450 SAE 10W-40, JASO MA Suzuki RM-Z owner’s manuals, via motomind.app 4-stroke maintenance guide Use the grade and JASO rating printed in your owner’s manual.
Shop tip. Two-strokes are different. The crank runs on premix and the gearbox has its own gear oil with its own drain plug.
Warm it up, park it level
Run the engine for a few minutes so the oil gets warm and thin. Warm oil drains faster and carries the dirt out with it. Then shut it off and stand the bike upright on level ground or on a stand that holds it level.
- Stand
Careful. Exhaust pipes and engine cases stay hot for a long time. Wear gloves for the next steps.
Open the filler, pull the plug
Take the filler cap off first so air can get in and the oil drains smoothly. Then remove the drain plug, and on KTM-family bikes the oil screen plug too. Let it drain until it only drips.
- Socket
- Drain pan
Shop tip. Push down on the plug while you turn the last threads by hand, then pull it away fast. You keep the hot stream off your hand.
Read the magnet, fit a new washer
Wipe the magnet and look at what it caught. A thin gray paste is normal wear. Flakes or chips are not. Yamaha says to open the crankcase if you find metal in the oil. Fit a new sealing washer every time, because the old one is already crushed flat.
- Rag
- New sealing washer
Careful. If you find chips, shiny flakes or bits of clutch, don’t just refill and ride. Find where they came from first.
Clean the oil screen
If your engine has a removable screen or strainer, pull it and wash it in clean solvent. Debris on it tells the same story as the magnet. Refit it with new O-rings.
- Parts cleaner
- New O-rings
Oil screen plug torque Bike Spec Source KTM / Husqvarna / GASGAS 4-stroke 15 Nm (11.1 lbf ft) KTM 250 SX-F 2024 owner’s manual, PDF p. 137 (M20x1.5, new O-rings) Yamaha YZ250F 10 Nm (7.4 lb ft) Yamaha YZ250F 2026 owner’s service manual, PDF p. 105 (oil strainer bolt) Not every bike has a removable screen at each change. Check your manual for its screen or strainer and torque.
Shop tip. On KTM-family engines the manual pushes the screen fully home with a pin wrench through the plug hole on the opposite side of the case.
Change the oil filter
Remove the cover screws and pull the old filter. Clean the housing, oil the cover O-ring, fit the new filter and torque the screws. KTM tells you to lay the bike on its side, fill the housing about a third full and soak the filter in oil first, so the engine never starts dry.
- Torque wrench
- Lock ring pliers
Filter cover screws Bike Spec Source KTM / Husqvarna / GASGAS 4-stroke 10 Nm (7.4 lbf ft) KTM 250 SX-F 2024 owner’s manual, PDF p. 138 (M6) Yamaha YZ250F / YZ450F 10 Nm (7.4 lb ft) Yamaha YZ250F and YZ450F 2026 owner’s service manuals, PDF p. 104-105 Honda’s owner’s manual leaves the filter job to the Competition Handbook. Use the torque from your service manual.
Careful. A pinched or missing O-ring leaks oil fast. Check it sits in its groove before you tighten the cover.
Refit the plugs to torque
Clean the sealing faces. Thread the drain plug in by hand with its new washer, then finish with a torque wrench until it clicks. The case is aluminum, so feel is not good enough here.
- Torque wrench
- Socket
Drain plug torque Bike Spec Source KTM / Husqvarna / GASGAS 4-stroke 20 Nm (14.8 lbf ft) KTM 250 SX-F 2024 owner’s manual, PDF p. 138 (magnet plug M12x1.5, new seal ring). Screen plug 15 Nm. Yamaha YZ250F 20 Nm (15 lb ft) Yamaha YZ250F 2026 owner’s service manual, PDF p. 105 (new gasket) Yamaha YZ450F 20 case / 10 tank Nm Yamaha YZ450F 2026 owner’s service manual, PDF p. 105 (crankcase 20 Nm, oil tank 10 Nm) Honda’s 2025 owner’s manual doesn’t print a drain bolt torque. Use the Competition Handbook or service manual value.
Fill with the right amount
Measure the oil instead of pouring until it looks right. Use the refill amount from your manual. It is a little more with a new filter than for an oil-only change. Stick with one brand and grade, since KTM advises against mixing oils.
- Funnel
- Measuring jug
Oil to add Bike Spec Source KTM / Husqvarna / GASGAS 450 1.20 l (1.27 qt) KTM 450 SX-F 2024 owner’s manual, PDF p. 143 KTM / Husqvarna / GASGAS 250, 350 1.0 l (1.1 qt) KTM 250 SX-F 2024 owner’s manual, PDF p. 138 Honda CRF250R 1.08 L with filter Honda CRF250R 2025 owner’s manual, PDF p. 79 (1.05 L oil only) Honda CRF450R 1.04 L with filter Honda CRF450R 2025 owner’s manual, PDF p. 79 (1.00 L oil only) Yamaha YZ250F 0.75 L with filter Yamaha YZ250F 2026 owner’s service manual, PDF p. 105 (0.73 L oil only) Yamaha YZ450F 0.96 L with filter Yamaha YZ450F 2026 owner’s service manual, PDF p. 105 (0.94 L oil only) Suzuki RM-Z450 1.10 L with filter Suzuki RM-Z450 owner’s manual, via motomind.app 4-stroke maintenance guide Suzuki RM-Z250 1.00 L with filter Suzuki RM-Z250 owner’s manual, via motomind.app 4-stroke maintenance guide Use the refill amount in your manual. Most list one number for a drain and a slightly bigger one with a new filter.
Run it, then check the level
Refit the filler cap, start the engine and look for leaks at every plug and the filter cover. Shut it off, keep the bike upright, wait as long as your manual says and read the level window. Top up only with the same oil.
- Rag
Level check Bike Spec Source KTM / Husqvarna / GASGAS 4-stroke Cold, mid window KTM 250 SX-F 2024 owner’s manual, PDF p. 136. Warm: between middle and top edge, 1 min after shutoff. Yamaha YZ250F Between min and max Yamaha YZ250F 2026 owner’s service manual, PDF p. 103-104 (run 2 to 3 min, wait 1 min) Yamaha YZ450F Window edge to max Yamaha YZ450F 2026 owner’s service manual, PDF p. 103-104 (oil at 60 °C, then wait a few minutes) Honda CRF-R bikes have an oil level window on the right side. Check your manual for when and how to read it.
Careful. Too little oil wears the engine fast. If the level drops between rides, find out why.
Sources
Log It And Know When It Is Due Next
MotoMind logs engine hours and every service job with notes, parts and cost, and shows each task as upcoming, due or overdue. Available to download on iOS.
