Need to change the oil on your Honda CB125E? Here's how to do it.
Warm oil drains quicker and more completely - you're supposed to change the oil with the engine at normal operating temperature. After warming it up - 5 minutes of running should do it - put the bike on the center stand. Be careful of the hot engine, exhaust and oil! Also, when running the engine don't leave it idling inside a room, like a garage - best done outside. When the bike is warmed up we like to put the key(s) in a bag, or put them on a piece of paper saying "DON'T START, NO OIL" - if you get interrupted, forget or have a helper it reduces the chances of starting it dry and wrecking the engine. You'll mostly be working on the left side of the engine;
The oil drains out of the engine through the sump plug, which is usually located at the lowest point of the engine so that the oil can drain as fully as possible. Look beneath the engine serial number to find it.
You need a 12mm socket or wrench to undo the drain bolt:
...and a container of at least 1L capacity to catch the used oil in:
You should get about 800ml out of the engine in this sort of change... but better to have more capacity than not enough! Remove the dipstick:
Undo the drain bolt:
Be aware that there's a crush washer between the bolt and the crankcase; you might drop it into the oil pan if you're not careful. Here comes the hot oil - watch out!
Almost exactly 800ml:
Inspect the crush washer. For the cost of them - next to nothing - we tend to change them every oil change. Honda recommends every second change, or every change if it looks like it needs it.
5 minutes is usually enough for the engine to drain; don't worry if there's still a few drips. Clean up the bolt and reinstall the washer + bolt:
Grab your torque wrench and set it to 30nm, or 22ft/lb:
Measure out slightly less fresh oil than what you took out. For example, if you removed 800ml measure out 700ml... it's much easier to top it up than to remove the drain bolt again to remove some. Pour the fresh oil in through the dipstick hole:
Reinstall the dipstick, start the engine and let it run for 5 minutes. Turn it off, let it rest for a minute and check the oil level. It should require topping up a little; add some oil, repeat the process and re-check the level. Repeat until it's full. Check the underside of the engine for any oil leaks before you go anywhere, and certainly at least again after the first post-change ride!
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