Why does having excessive engine oil create a popping sound?

[redred]

Hi,

 

Once I rode a bike with engine oil exceeding the FULL line indicated on the gauge. I noticed during deceleration, your will hear popping sounds from your exhaust. It kind of sound like very tiny little explosions, like secondary school putting flint into test tube filled with hydrogen experiment.

 

Anyone knows why?

[xXxRatedxXx]

cos inside your chamber got explosion...then explode out of your exhaust pipe.... kaboom!!

[Marcheline]

From what I can visualise for a 4 stroke engine, excessive engine oil will create positive pressure within your crankcase, hindering the motion of the piston on the downward stroke. This.. I think, would change the way combustion takes place within your engine.

 

By the way, the +ve pressure is caused by excessive engine oil vapor being produced due to the excess amount.

 

I don't see how the popping sound is caused by the air/fuel ratio (lean/rich) as there is no relation between the amount of oil you have in your engine and the carburettor.

[Raptor]

Engine oil level has nothing to do with overlean mixtures causing exhaust backfiring.

 

Overfilled crankcases will only cause excessive oil mist coming out of the crankcase breather which is connected to the air filter box and cause the filter clog and cause poor engine performance due to over rich mixtures.

[Pandoras Kitten 3]

That explains my "Subaru Impreza exhaust sound effect" when I collected the bike.; Subsequently solved with draining EO back to normal levels. Thanks mepkoh :3

[redred]

From what I can visualise for a 4 stroke engine, excessive engine oil will create positive pressure within your crankcase, hindering the motion of the piston on the downward stroke. This.. I think, would change the way combustion takes place within your engine.

 

By the way, the +ve pressure is caused by excessive engine oil vapor being produced due to the excess amount.

 

I don't see how the popping sound is caused by the air/fuel ratio (lean/rich) as there is no relation between the amount of oil you have in your engine and the carburettor.

 

Engine oil level has nothing to do with overlean mixtures causing exhaust backfiring.

 

Overfilled crankcases will only cause excessive oil mist coming out of the crankcase breather which is connected to the air filter box and cause the filter clog and cause poor engine performance due to over rich mixtures.

 

the back pressure in the crank is making the engine work harder..

in th e process giving rise to inefficiency..resulting in a rich mix /unburnt fuel.....thus back firing..as when u engine brake..

 

I understand. That must definitely be bad for the engine in the long run. Appreciate the enlightenment!

 

That explains my "Subaru Impreza exhaust sound effect" when I collected the bike.; Subsequently solved with draining EO back to normal levels. Thanks mepkoh :3

 

Exactly, I got to admit sometimes the sound seems quite awesome.

[ali_baba]

nothing to do with engine oil level ...

 

too much engine oil .. maybe sluggish feeling..

too less engine ... piston jam ..

[crazydj]

Too much EO sucks. Engine so hard to start, so difficult to kick, super sluggish performance, air box full of oil... Its not worth it.

 

I rather go with low EO than too much EO.

[.CandyZam.]

Too much EO sucks. Engine so hard to start, so difficult to kick, super sluggish performance, air box full of oil... Its not worth it.

 

I rather go with low EO than too much EO.

low eo on 4stroke = piston jam:angel:

[JbAtRaCeR]

I'm not sure about smaller 2B bikes...but on class 2a bikes,the engine have this pressure relief valve that opens just incase the oil pressure increases. And one more thing,overfilling the oil sump with too much oil will cause the oil to foam.

 

When the oil level reached too high inside the crankcase,the crackshaft will churn the oil into foam.Bubbles get sucked into the strainer and as we know,air is a poor lubricant.Your main bearings will suffer the most...

[crazydj]

But somehow, with low EO, the feeling is very shoik and light. But the engine will be noisy and loud.

[Pandoras Kitten 3]

Mototiams (at least some) like to overfill EO for some reason. They claim engines "eat oil", which is a load of cow dung.

 

I'd rather run with lower EO levels as aforesaid and self-monitor the EO level.

 

Thank god there's a SBF forum to warn me of the perils of real world incompetence

[ben1112]

Who's incompetent? If you do it your way as a motorshop den very soon it will close down. Hi mileage 4st bikes eg, phantom does burn engine oil due to wear of piston/ring allowing oil to seep past the clearance. Too much oil will only dull performance whilst too little on an engine that burns oil spells disaster.

 

They try to err on the safe side. So if an engine can 'EAT' oil, you can 'EAT' your own words too!!

[xXxRatedxXx]

Mototiams (at least some) like to overfill EO for some reason. They claim engines "eat oil", which is a load of cow dung.

 

I'd rather run with lower EO levels as aforesaid and self-monitor the EO level.

 

Thank god there's a SBF forum to warn me of the perils of real world incompetence

 

Who's incompetent? If you do it your way as a motorshop den very soon it will close down. Hi mileage 4st bikes eg, phantom does burn engine oil due to wear of piston/ring allowing oil to seep past the clearance. Too much oil will only dull performance whilst too little on an engine that burns oil spells disaster.

 

They try to err on the safe side. So if an engine can 'EAT' oil, you can 'EAT' your own words too!!

 

whoaaaaaaaaaaaaaaa!!!!

[yt]http://www.youtube.com/watch?v=VD89Z0_Rav8&feature=related[/yt]

Edited April 12, 2010 by xXxRatedxXx

[Raptor]

The piston of a 2 stroker ONLY have compression rings. The lubrication for the cylinder wall comes from the 2T that is mixed with the fuel either premixed at the tank or normally with the 2T pump whose discharge rate is controlled by the throttle via a tandem cable set up.

 

Two strokers use this premix method for lubricating the upper (sometimes called the hot section) cylinder areas, piston, conrod and piston bearings. The fuel mixture that is being used for combustion doubles up as the one carrying the lubricating oil to these areas... not an oil pump.

 

That is why running with low fuel/2T mixture ratio or tuning the bike too lean.. will result in failure of one or more of the abovementioned components.

 

The 4 stroke engine's piston has compression AND oil rings. The oil ring is the bottom most ring, is not solid but with a wafer looking design in it.

 

In a 4 stroke engine, engine oil is sprayed or splashed onto the cylinder walls when the engine is running hence the words "forced lubrication" because oil is forced around the engine by an oil pump.

 

The purpose of the oil ring is to scrape the oil off the cylinder wall during the downstroke leaving a very thin layer for piston lubrication... inevitably the engine is burning up a bit of oil each time the engine is running. We only realise oil burning as a form of blue smoke emitting from the exhaust as excess oil is being burnt on the cylinder wall and the spark plug gets coated in oil or black soot but oil burning is going on all the time... just at a very slow rate.

 

Since two stroker's upper cylinders are lubricated by fuel/oil misting... their crankcases have their own oil sump. The lubricant in a 2 stroke's crankcase is purely for the gearbox train and the clutch plates only... nothing else. That is why they can put SAE 80 gear oil in their crankcases instead of engine oil. And they don't need an oil pump cos the oil is not going anywhere.

 

So..... overfilling engine oil in a 2 stroker does not make sense... in a 4 stroker it does make sense and can save the engine and costly repairs.

 

Learn and don't be connned by unscrupulous mechanics, they capitalise on your ignorance.

Edited April 13, 2010 by Raptor

[xXxRatedxXx]

The piston of a 2 stroker ONLY have compression rings. The lubrication for the cylinder wall comes from the 2T that is mixed with the fuel either premixed at the tank or normally with the 2T pump whose discharge rate is controlled by the throttle via a tandem cable set up.

 

Two strokers use this premix method for lubricating the upper (sometimes called the hot section) cylinder areas, piston, conrod and piston bearings. The fuel mixture that is being used for combustion doubles up as the one carrying the lubricating oil to these areas... not an oil pump.

 

That is why running with low fuel/2T mixture ratio or tuning the bike too lean.. will result in failure of one or more of the abovementioned components.

 

The 4 stroke engine's piston has compression AND oil rings. The oil ring is the bottom most ring, is not solid but with a wafer looking design in it.

 

In a 4 stroke engine, engine oil is sprayed or splashed onto the cylinder walls when the engine is running hence the words "forced lubrication" because oil is forced around the engine by an oil pump.

 

The purpose of the oil ring is to scrape the oil off the cylinder wall during the downstroke leaving a very thin layer for piston lubrication... inevitably the engine is burning up a bit of oil each time the engine is running. We only realise oil burning as a form of blue smoke emitting from the exhaust as excess oil is being burnt on the cylinder wall and the spark plug gets coated in oil or black soot but oil burning is going on all the time... just at a very slow rate.

 

Since two stroker's upper cylinders are lubricated by fuel/oil misting... their crankcases have their own oil sump. The lubricant in a 2 stroke's crankcase is purely for the gearbox train and the clutch plates only... nothing else. That is why they can put SAE 80 gear oil in their crankcases instead of engine oil. And they don't need an oil pump cos the oil is not going anywhere.

 

So..... overfilling engine oil in a 2 stroker does not make sense... in a 4 stroker it does make sense and can save the engine and costly repairs.

 

Learn and don't be connned by unscrupulous mechanics, they capitalise on your ignorance.

 

Once again... raptor comes to save the day with a wealth of useful information!!

 

Learnt something new today...

 

Allow me to contribute a diagram for those not in the know...

 

http://howautowork.com/part_1/ch_1/images/The%20piston.JPG