Demystifying one of the most incorrectly used engine related term (in India)..
What is Engine Knocking?
If I ask this question to most of the ones who rides a motorcycle in India, I can bet that the most probable answer would be something like this:
"If you are riding at top gear and the bike is at slow speed say around 20 kmph; in such a situation if you suddenly twist the accelerator without shifting down a gear, then instead of a smooth pick up, the engine will start behaving as if it’s gasping for breadth and struggles to move forward. This causes the bike to move in a jerky manner instead of moving forward smoothly.
This is knocking".
I wouldn’t be surprised if the above answer comes not just from a layman but even from many of out so called "desi" bike experts
What has been described above is actually Engine "SNATCHING" and NOT Engine "KNOCKING".
Why does Engine Snatching occur?
Imagine someone is holding your hand casually and loosely. Now if he/she decides to pull your hand suddenly then you will surely experience an unpleasant jerk won’t you? The same phenomenon occurs with the engine, when the slow moving parts inside the engine are subjected to a sudden motion.
What we instinctively do in such a situation is either shift down a gear or let the engine revs rise by slipping the clutch.
If that is Engine Snatching then what is Engine Knocking?
Engine Knocking is actually a Pinging/Metallic sound which can be heard from the engine when the air fuel mixture is not burnt in the optimum manner.
Causes of engine knocking could be: Due to..
- Carbon deposits
- A lean air-fuel mixture
- Low coolant level, or cooling system problem that causes the engine to run hotter than normal
Posted below is a video in which a car engine makes "Knocking" sounds when revved: Click here, if one cannot see the video.
For more info on Engine Knocking, click here..
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12 Comments:
That's a great read Dude!! Clears a lot of concepts :)
Fantastic stuff. Simple and lucid. much better than the stuff available on other amateur auto blogs out there which are just interested in spreading sensational scoops and half cooked gyan (knowledge)
thanks again
the above article clears the term 'snatching'...
however i m still not sure what 'knocking' is. wud have been better if u cud give more information on hw to identify knocking..is it distinctly different than the actual engine noise??
wud b gr8 if u cud shed more light on it :)
Thanks Sajal and anonymous,
@Prakash, knocking occurs due to improper detonation inside the engine.. the resulting sound is a Metallic "Pinging" noise..
I have now added a video of a car engine which makes "knocking" sounds when revved. Hope it makes the "knocking" explanation clearer now.
Thanks for the info.. never heard of engine Snatching before
i want a little clarification based on engine knocking.. According to d feature 'Anti-Knocking Mechanism' in new TVS-Jive ( http://www.tvsjive.com/ ),its mentioned dat one can drive in any gear at low speeds. so wen referred to knocking it means dat it is something which is related to proper speed nd correct gearshift(snatching).as mentioned above it shuld b mentioned as anti-snatching mechanism.Then y does TVS use such a kind of wrong terminology???so to what extent is engine snatching more appropriate than engine knocking?
@the guy who has posted above, maybe TVS is just using the commonly used terminology so that it is easier for the average joe to understand.
Thanks for the info.. never heard of engine Snatching before
thnx for d informative article....i have a Qs:
which would be more fuel-economic way to handle snatching?
- applying the clutch and revving up the engine
or
- shifting the gears down and then up and revving up the engine
Thanks a lot.
@Rajyavardhan,
According to me its always better to shift down to avoid snatching rather than making the clutch slip.
awesome explaination
can you please explain engine snatching in more detail?
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