Pinging

[racefactory]

Pinging/knocking- what does it sound like? under what conditions is it most likely to occur?

I'm a little concerned because I had to run 91 (which is 87) in a 2005 636 when I ran out of fuel. Ran it for about 200km. It's supposed to use 95 RON in manual.

Bike felt exactly the same, no sound or anything.

I don't think they have knock sensors that will retard the timing so i'm worried about detonation harming the engine.

[Marmoot]

When you pull the throttle and apply quite a load to the engine, such as starting uphill or accellerating briskly out of an intersection, you can feel some sort of faint "tek tek tek" from within the engine or somewhere between your legs.

With single cylinder bikes, it is easy enough to feel.
With multicylinder bikes they are less so.
With cars, can be quite hard. Sometimes they are audible and sometimes they are not.

Running 91 on a 636 would be fine for short period. It won't hurt the engine much.
It may become a problem if the day is extremely hot and you still whip the bike around at low speed and heavy load.

I wouldn't loose any sleep over it if I were you. Just switch back to 96 over the summer and enjoy the ride.

[240]

It sounds like a rattle or knock when under a load like going up a hill in a high gear or if you snap the throttle at low speed.
If you heard nothing I wouldn't worry about it.

[Marmoot]

Detonation
http://blog.mlive.com/chronicle/2007/12/large_Explosion.jpg

[racefactory]

Detonation
http://blog.mlive.com/chronicle/2007/12/large_Explosion.jpg

thanks, I didn't hear any sounds at all even though I was giving it a little blast at times. Usually pretty tuned into sounds the bike makes.

Think I know that sound you guys are talking about now... is it the same one that old shitbox cars make when they are under load pulling away on a hill? Is that high carbon deposits increasing compression ratio making it knock?

That picture makes a lot of sense now marmoot

[Marmoot]

Think I know that sound you guys are talking about now... is it the same one that old shitbox cars make when they are under load pulling away on a hill?

Yes! :) That is knock.
It sounds "knock knock knock" ...hence the name, I suppose.

More definitive info here (http://www.misterfixit.com/deton.htm)
Basically,
- Detonation is pre-ignition, where the air/fuel mixture ignites before they should. Mainly due to a leftover ember (carbon deposit), or if the mixture is too hot (not enough octane, or not enough fuel to quench the cylinder/piston heat, or the compression rate is too high).
- The knock is the result. Either just the shockwave, or the engine internals (mainly the piston) being forced to move where it could not, resulting in it tapping the cylinder head, or the piston pin rattling, etc.

[avgas]

On the 636 the only time you would notice it is when your taking it easy. If your giving it hell you will never notice it as its almost non-existent in peak revs.

[Motu]

Yes! :) - Detonation is pre-ignition, where the air/fuel mixture ignites before they should. Mainly due to a leftover ember (carbon deposit), or if the mixture is too hot (not enough octane, or not enough fuel to quench the cylinder/piston heat, or the compression rate is too high).
- .

That is pre ignition - detonation is post ignition,which is often not heard.Pressure from the flame front causes spontanious combustion in quench areas,the coliding flames fronts are what causes the damage.

Pre ignition - fuel ignites before the spark event.

Detonation - post ignition,fuel ignites after the spark event.

[SMOKEU]

If it starts sounding like a diesel then it's time to worry.

[Marmoot]

That is pre ignition - detonation is post ignition,which is often not heard.Pressure from the flame front causes spontanious combustion in quench areas,the coliding flames fronts are what causes the damage.

Pre ignition - fuel ignites before the spark event.

Detonation - post ignition,fuel ignites after the spark event.

Ah, ok. Thanks.

[notme]

If it starts sounding like a diesel then it's time to worry.

Speaking of which - something really interesting to see (which you won't really nowadays with EFI) is a car "dieselling" i.e. ignition gets switched off and the thing keeps running, sometimes for minutes at a time! It usually happens when there's lots of carbon build up in the cylinders - it stays hot and ignites the fuel when it's compressed, which causes heat which keeps the carbon hot....etc.

[SMOKEU]

Speaking of which - something really interesting to see (which you won't really nowadays with EFI) is a car "dieselling" i.e. ignition gets switched off and the thing keeps running, sometimes for minutes at a time! It usually happens when there's lots of carbon build up in the cylinders - it stays hot and ignites the fuel when it's compressed, which causes heat which keeps the carbon hot....etc.

Same thing happens to my dads car, but only for a few seconds.

[Pixie]

Yes! :) That is knock.
It sounds "knock knock knock" ...hence the name, I suppose.



So why are knockers so named?

[Marmoot]

So why are knockers so named?

Swing them hard enough, and if they are decent sized, they would knock your face out of alignment.

[MSTRS]

AKA - bitch slapped.