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Discussion Starter · #1 ·
Does anyone have access to a "cutaway" diagram/picture of a K12 motor?. Can't seem to find one. Simply stating, an inner view of the pistons, valves, and where the spark plug is positoned in the top of the cylinder. I have a dumb reason to ask. Have you ever heard that a spark plug works much better if the electrode is positioned a certain way?.
Meaning, when you find out how the piston rises to the top of the cylinder, like on a V-8 car, if you "allign" the curved part of the plug (which the electrode fires upon) at an exact vertical it fires better, supposedly, this is what drag racing guys do. Think I'm nuts don't you?.
 

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Your nuts.

I'll look later to see if the Service Manual has such a drawing - I seem to recall it does.

Two points:

1) I guess if the spark plug propagated the wave front differently in different directions it might make some tiny difference - but I doubt it could be measured compared to other variables.

2) How would you "align" the electrodes? Trial and error with a marked plug and shims?

3) Sounds like someone needs another hobby!
 

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plug index

We did index the plugs on our drag cars and felt it made a difference but were never able to measure it, How would you index the dual ground plugs that are stock in our bikes anyway.
 

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Indexing a plug (chosen placement of the ground electrode) is for the purpose of controling the flame front and getting the most of each combustion event.

The diagram you are looking for would show that the head is a standard low depth hemispherical shaped head. The four valves surround the plug that is in the center.

The fact that the spark plug can be had with different ground electrode styles and placement is important here but secondary to the squish pattern of the head.

As our head is a low depth hemi head we will gain minimum improvement over indexing. (squish turbulence is consistent and runs from the center out )
Our only benfit would be to count on the minimal effect of flow from overlap and judge the difference between the placement of the ground electrode at 3 and 9 oclock , 12 and 6 oclock / or the 45 degree angles in between (similar to 10:30 and 4:30.
Again - this gain would be minimal.

The object is to point the spark plug in the direction of maximum entrance turblence. You want the open area to point to the area of maximum squish (just prior to the combustion event)

Or

Your talking about the ground electrode placement on a single ground electrode(standard plug) .
The ground electrode on a regular single ground electrode plug does serve a purpose and can be set correct and incorrect as far as how you bend the electrode while setting gap.

For maximum power on a single electrode plug it must be completely flat and centered over the center electrode. if it is not the spark will take the shortest path from the center electrode to the ground . a slightly bent or angled single plug ground will cause deviations up to 3% of maximum power.


If you are looking for max power here you should play with gap. Factory settings always allow for the bike to be run to the end of the useful life of the plug without the need to pull and regap the plug. (made to runn a bigger gap - electrodes wear during use - ignition must compensate) If a larger gap produces more power then go with it. You may have to change or regap the plug a little sooner but thats what racers do . Plus we have to drink beer after doing something.

Overall - let this be a final mod for you. Increasing flow characteristics , controlling backpressure and properly mapping gas/ air mixtures will provide far better increases.
But there is nothing wrong with taking a permanent marker and putting a line on the white ceramic where the grounde electrodes are to see where it ends up and make sure that you have consistent setup in all cylinders. (Balance is everything )

But - If you are performance crazy . Try the differnt ground placements compositions and gaps. The increase is very small but if you have a dyno and a lot of time you will find something.

If you really want to have some fun with a hemi head you may wish to consider multiple capacitive spark discharge under 3K rpm (Low turbulence) or variable magnetic multiple spark discharge for max life /stability/ fuel milage and power.

The bike is stock set for a single spark discharge for each combustion event as well as a dumping spark to offest the matched cylinder.
 

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Engine "pictures"

I am attaching two pictures of the K engine. Perhaps not exactly what you asked for but might do anyway.

My guess would have been that the obstruction caused by the curved tip on a single electrode plug would be more significant than the orientation. Thus anything that reduces the profile of this obstruction would be more significant than the improvement achieved by the orientation of the obstruction. Meaning, you could achieve a symetrical wave front if the plug could work without the curved protruding tip. There is such a spark plug, isn't there?

Ron
 

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rfespinosa said:
I am attaching two pictures of the K engine. Perhaps not exactly what you asked for but might do anyway.

My guess would have been that the obstruction caused by the curved tip on a single electrode plug would be more significant than the orientation. Thus anything that reduces the profile of this obstruction would be more significant than the improvement achieved by the orientation of the obstruction. Meaning, you could achieve a symetrical wave front if the plug could work without the curved protruding tip. There is such a spark plug, isn't there?

Ron
I bought some once for my 300zxtt. I probably still have them somewhere in the garage. They had a circular ground electrode that encompassed the tip at about the same height as the tip. I couldn't tell a difference in the power but the idle was rough so I took them out. --Jerry
 

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Discussion Starter · #7 ·
Plugs.......

fasteddieb said:
Your nuts.


2) How would you "align" the electrodes? Trial and error with a marked plug and shims?

Simple, yes, you use shims (extra crush washers/rings) and you mark the side of the plug with a magic marker alligning the electrode. As you put the plug in you can easily see the mark and go from there. Anybody ever tried the NGK Iridium's ??.
 

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Multi-electrode plugs

If I'm not mistaken, whether you have one side electrode, two, four or a solid ring, the spark will still just jump in one place.

When you test an aircraft spark plug (the "massive electrode" rather than the "fine wire") you can observe the plug in action. If the two gaps are close to even, you watch the spark move from one side to the other, but...

...in action in the engine the spark is of such short duration you get ONE spark to ONE side electrode.
 

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On a similar note, Does the K make one spark or several? And does anyone make a multi spark unit for it? Car freaks claim it helps a lot, tho I have no personal experience with it.
 

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This is the best diagram I have of a K engine - got it on the old site I think - probably doesn't help a bunch but it looks cool....

alow
 

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Not quite a cutaway...

Here is a pic for ya. This is the original motor from my 03 K-RS. Believe the crank bearing siezed on cylinder #1, things went bad from there... No one hurt, just with out the bike for three weeks. Boo Hoo... All was fixed/replaced under warranty.

Cheers! :wtf
 

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