A two-stroke has no oil filter and no oil pump for the crankcase. The gearbox and clutch share a separate supply of oil that is splashed around, and the engine itself is oiled by pre-mix or an oil injection pump. The engine oil is always fresh, but the gearbox oil still ages and must be changed at the interval in the manual.
Safety
- Hot oil burns. Let the engine cool a little.
- Keep oil off the rear tyre and the brakes.
Steps
- Warm the engine briefly so the oil flows, then stop it and stand the bike upright.
- Put the drain pan under the gearbox drain bolt. Look in the manual for the right bolt and the amount of oil.
- Remove the filler cap or level plug to let air in. Remove the drain bolt and let the oil drain fully.
- Look at the old oil for metal or milky colour. See Inspect drained oil for clues.
- Fit the drain bolt with a new washer and tighten to the torque in the manual. See Tighten drain and filter bolts without stripping them.
- Pour in the amount and type of oil the manual gives. Many engines have a level plug as well: the oil should reach that hole.
- Refit the cap or plug and wipe up any spills.
Check your work
- The level is right when checked upright.
- No drips from the drain bolt.
- The clutch works normally and the bike pulls away without slipping.
If it did not fix the problem
- Oil is getting into the engine and the exhaust smokes: Old two-stroke smokes heavily.
- The gearbox level keeps rising or the oil looks thin: the crankshaft seal on the gearbox side may be leaking. See Remove and fit an engine oil seal.