I am riding a Honda CBR150R and my odometer reading is 500 KM. Today, I went to change my engine oil and the service engineer poured around 1400 ml of engine oil, my bike manual says the engine oil capacity is 1100ml during regular draining and 1300ml during engine overhaul.

After then, I rode around 3 km back to my home and drained the excess oil myself, now it's in the correct level.

Want to know, did that overfilling have done something significant damage to my engine just riding 2-3 km, my rpm count was not more than 5x1000?

Thank You

  • 1
    How did you confirm the engine oil was overfilled? Do you have a sight window or a dipstick? What was the reading before you emptied the excess?
    – raydowe
    Commented Apr 23, 2017 at 15:11
  • ya I checked the dipstick, it was all the way submerged in the oil, and the mechanic poured one full and one half bottle of oil... 1.4L oil should always be excess for a 150cc baby cbr, i assume Commented Apr 23, 2017 at 15:34
  • 2
    Yep, sounds like way too much. I would stop in and let the mechanic know about the mistake. Everyone has bad days and makes mistakes, but you shouldn't be expected to pay for a mistake of this magnitude.
    – raydowe
    Commented Apr 23, 2017 at 17:10
  • You already got a good answer, what I can add is the following: The given value of 1100ml is normally for when you only change the oil. After its first 500Km the engine should have also got the oil filter changed, which means that slightly more oil is required when refilling. It won't be much for such a small engine (I'm guessing no more than 100ml), but it means that it was less overfilled than you feared. As stated elsewhere, I also think your bike should be OK. Commented May 3, 2017 at 15:29

2 Answers 2


It's doubtful. The primary issue with overfilling in a wet sump engine is that the crankshaft can contact the top of the oil in the pan and beat it into a froth. This causes air to be ingested into pickup and pump, which will result in a loss of oil pressure. There is also a possibility that there will be an increase in pressure in the crankcase, which is bad for some oil seals.

As long as you didn't have a low oil pressure light come on during your ride, it's safe to say 2-3kms won't hurt anything. Just ensure the oil level is correct before starting the bike again, and don't worry about it.

  • thanks, want to know exactly what amount of overfill can damage right away? i heard that manufacturers always keep a safe margin knowing the fact that user will make an error during filling Commented Apr 23, 2017 at 15:41
  • It's going to be very hard to get even a rough estimate on this. If you haven't noticed any changes in the engine, I'd just forget about this incident.
    – raydowe
    Commented Apr 23, 2017 at 17:09
  • How does frothing of the oil cause increased oil pressure?
    – Ives
    Commented Apr 25, 2017 at 19:19
  • @Ives, frothing itself doesn't increase oil pressure, and at the time of this comment the associated answer states it decreases it. But this too is unlikely due to the breather. if extra heat is built up as the result the oil pump failing this heat does not increase pressure but rather leads to rapid wear. so on another bike decrease in oil pressure id agree with, but not increase in other pressure as suggested. ps the worse of the wear for the OP would be in the overhead cam, valve stems, rocker arms, as no pump would leave them dry (the rest of the engine is primarily lubercated by splash)
    – axa
    Commented May 3, 2017 at 19:25

On a cb type engine, the oil pump is under the right side cover, which is separated by a wall if you will. oil passes between via (one or more im not honestly sure) small channels which is below the oil line in the case, and even more so in an overfilled case. That's good news because you dont need to worry about frothing stopping your pump, as that would be extremely unlikely that bubbles sink in the downward direction and into these passages

You can see the right side case, and division in this link:

Also the cb type engine has a breather port that would easily release any pressure built up in the case, so excessive pressure wouldn't be a possibility unless the roughly 14mm hole gets plugged in an extremely unusual manner. And any seals, if any in this region, i dont see being compromised because if pressure somehow builds in the case to high levels, its likely the gases/liquids first start to blow up the pump, or even through the gaps in the piston rings before breaking through the left side out the crank/stator bearing. And you would likely know it when dark smoke starts coming out the exhaust.

Unfortunately while the larger cb's do, I do not think the smaller ones, including yours, have an oil pressure sensor, so no information can be had that way.

Frankly if there isn't excessive oil blowing out the aforementioned crankcase vent, and the oil level is not below the min mark, I do not feel you need to be concerned with the oil level, nor bother to go out of your way to check into it.


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