Why the 1200LC is not Twin Spark

[Pavlovski]

So help me if I'm wrong....but ysterday I had a look at a mate of mine's 1200LC GS and noticed that it only has 2 spark plugs.

Later 1150GS models were twin spark (4 spark plugs in total) and the previous generation 1200's were also twin spark, so why would the new LC not be twin spark?

As far as I know twin spark has more to do with fuel efficiency than power...is this correct?

[Eendstop]

I read a version that the additional plugs got added as a way to meet emission standards.  They probably now have some cheaper alternative or maybe VW showed them the way

[whitedelight]

I read about this a while back. Due to many engine changes,such as a down drought setup,they could up the the compression ratio a little. So basically the more compact combustion chamber only required a single spark.
And yes the older twin spark did help towards emission controls.

[gser]

I read a version that the additional plugs got added as a way to meet emission standards.  They probably now have some cheaper alternative or maybe VW showed them the way

My gedagte loop ook so Eendstop.
 Dus, nie n werklike 2-Vonk waarby altwee vonkproppe gelyk vuur nie.
 Die tweede vonkprop vuur heelwat "later" om die onverbrande gasse te help verder verbrand om sodoende n "skoner" uitlaatgas te help verseker. Ek dink dit dien die doel mits die uitlaatstelsel standard is of indien die klankdemper 'n EU, ens. afkoop/aanvaarding het.
Die LC is van meetaf ontwerp/ontwikkel/getoets om aan 'n hoer EU-uitaatgas vereistes te voldoen waaraan die ouer enjins nie aan sou voldoen het nie.
Enjinontwerp-Evolusie in werking.

[Draadwerk]

My LC het 6 plugs. 😉👍

[gser]

Met n wyntjie daarby ! LOL

[Pavlovski]

So in terms of cleaner exhaust gasses.... Would the second spark plug then sort of loose its purpose if you have a free flow exhaust system? Or if you've removed the catalytic converter?

[whitedelight]

So in terms of cleaner exhaust gasses.... Would the second spark plug then sort of loose its purpose if you have a free flow exhaust system? Or if you've removed the catalytic converter?

The second spark was to burn unspent gas. So you would have better emissions. So a cat con would perform the same function. The free flow exhaust would just move the exhaust fumes quicker.
Now you find with all the bike manufacturers they run them a little leaner in the lower revs to help with emission tests.

[Leo]

If they brought the current model out as a twin spark, how/what would they upgrade 3 years from now?

They can't just add high lift footpegs, different colors and racing mirrors!! 

At least now they have the option of adding twin spark as well 

[gser]

So in terms of cleaner exhaust gasses.... Would the second spark plug then sort of loose its purpose if you have a free flow exhaust system? Or if you've removed the catalytic converter?

The second spark was to burn unspent gas. So you would have better emissions. So a cat con would perform the same function. The free flow exhaust would just move the exhaust fumes quicker.
Now you find with all the bike manufacturers they run them a little leaner in the lower revs to help with emission tests.

The cat con can only convert a % of "bad" combustion, the "good" combustion" should in the total combustion cycle of the total efficiency
 of the whole combustion cycle to set requirements in the users/client design inputs to conform to EU standards in an engine. It starts with " to spec fuel " to be converted into automotive motion. For a starter, in a laboratory-dyno. eg. a EU test lab, the fuel that is used is to a calibrated EU fuel specification. ETC . .
It is a "repeatable science" that can be tjippoded, the test procedures for the dyno/lab test can be downloaded. 

 

[T Rex]

The old LC's won't work as aircraft engines then ....

[hedleyj]

Advances in induction systems have progressed in leaps and bounds over the years.

One of the more significant of those is Striated injection mapping. Which feeds fuel in as the combustion requires it. Hence far more accurate mixtures and leaner/cleaner emissions

[2StrokeDan]

The addition of water jackets in the head is possibly a cause for having to drop the 2nd spark plug. No space for it.

[OomD]

The addition of water jackets in the head is possibly a cause for having to drop the 2nd spark plug. No space for it.

As far as I know the water never goes near the head, but only flows around the base of the sleeve.

But then, I've been wrong before. Once. I thought I was wrong, but I was mistaken...

[2StrokeDan]

The addition of water jackets in the head is possibly a cause for having to drop the 2nd spark plug. No space for it.

As far as I know the water never goes near the head, but only flows around the base of the sleeve.

But then, I've been wrong before. Once. I thought I was wrong, but I was mistaken...

 
Mine was also only a guess.

[Wes]

These days i am sure 99.99% of cars run a single spark plug , second plug is not neccesary on modern engins .
Honda 1.4 jazz 2007 i know has twin sparkl plugs per cylinder

[TheBear]

These days i am sure 99.99% of cars run a single spark plug , second plug is not neccesary on modern engins .
Honda 1.4 jazz 2007 i know has twin sparkl plugs per cylinder

I think, all through history 99,99% of cars were single spark.  So were bikes.  Twin spark became a bit of a hit in the late 90's when combustion gasses became a bigger issue.  With more modern technology, twin spark seems to be on the way out again.

[jaybiker]

I thought it was because the designers were really concerned to bring down the cost and complexity of DIY maintenance.

And then the missus thumped me and said "Are you going to doze there all bloody day?" 

[alanB]

Twin spark ignition is normally used in cars to maximise the amount of air/fuel mix burned before the exhaust valve opens.  Because the flame front begins at two different points at once in the combustion chamber, the combined flame front can reach further in the same time.

This has benefits for high compression engines to reduce knock, because more/all of the fuel can be burned before the remaining mixture auto-ignites due to high pressure.

It also will improve fuel efficiency and emissions because less of the fuel air mixture is wasted.

The most likely reasons why BMW neglected it in later models are IMO:
1) Not enough space
2) Not enough benefit to warrant the extra cost and complexity
 

[Welsh]

My view is the previous ones were engineered around a moving emissions target, later one have a target to engineer to, until they move the posts.