Topic: Modifying spark plugs

[Scrubs]

Has anyone tried the spark plug mod as mentioned on the cyclex site?
Which basically involves trimming a small amount off the electrode to make it almost fire from the side.

Here is the exact wording:

Modify Your Spark Plugs For Free Horsepower.

There are many gizmo's that have claimed power increases through out the years
( splitfire spark plugs, indexing spark plugs, etc ). Here is a modification that works:

Bend up the negative electrode on your spark plug and cut approx 3/16 off. File the sharp edges edges and bend the negative electrode back to your desired spark plug gap.
Essentially turning your spark plug into a side firing plug.
Gasoline does not explode in the combustion chamber,  it burns.
Nitro is the only fuel that explodes.
With this in mind we must remove any obstructions slowing down the burn ( the negative electrode )
Attention to detail will make you a winner or run better than others. 


Any thoughts?

[Scrubs]

Seems to be a fairly common mod http://www.instructables.com/id/Save-Gas-And-Incerase-Horsepower-By-Side-Gapping-S/
Anyone got any first hand experience? would this change the temp of the plug - richening or leaning the mixture?

[TheHun]

I've done it...always  have in all my cars if I didnt use Brisk plugs....made my CB smoother at idle, not as choppy. Power gains probably none, but the smoother engine is worth a little scrapping in my book

[MJL]

I tried it in a v8 motor once, didn't notice anything.  The instructions I used were to file the electrode back to the middle of the center electrode.  While the theory is good, video presents a spark that moves around between the electrodes, so I don't really see any benefit.

On a small engine like a motorcycle, every little bit helps.

[Soos]

I believe pinhead has done this....


After my #3 spark plug boot went south(ripped) to my iridium spark plugs allowing a small electrical storm to go on under my tank, I switched to a old set of d8's along with the older wires(with resistive spark plug boots)...

For me at the time, it was simply a cheaper alternative to new boots, as well as a quick fix.
The d8's I used already had 15,000 or so miles on them.


Then I side gapped them.
As far as HP gain?
Dunno.
Idle does seems better with the side gapped plugs though.


I just took a dremmel and cut off enough material to make the edge of the bent electrode JUST match the OD of the center electrode.
I then set the gap at roughly 0.040.
I know thats WAY too wide for "normal" applications, but I am running 2.4 ohm coils and a dyna2000.


So about 3k miles later, I'm not dis-satisfied with my side gapped plugs, but still would rather run my iridium plugs though.



l8r

[Scrubs]

I know thats WAY too wide for "normal" applications, but I am running 2.4 ohm coils and a dyna2000.


So about 3k miles later, I'm not dis-satisfied with my side gapped plugs, but still would rather run my iridium plugs though.

Interesting. I am running the D8's also. What would the optimal plug I should be running on 3ohm green dynas
with Hondaman ignition and resistors installed - Using 8mm grey Supression wires? I'm unsure of caps but is what
came included with the wires from Dyna.

[Soos]

Dunno the "correct" plugs for your setup, let alone the "correct" ones for my setup.

I do know that you are not supposed to use resistive boots with iridium plugs as most are "automotive" type plugs, and have a built in resistance motorcycle spark plugs do not have.

When I initially ran the iridiums with resistive spark plug boots, I had problems.
After a bit of reading and realizing the iridiums I used had a built in resistance, I dumped the boots, and went to the automotive style connections. straight from the coils with no additional resistance from the motorcycle spark plug boots.





This post did spark the thought I had a while ago about wanting to inspect my plugs though.
I just pulled all 4 of them, and noticed the center electrode is getting worn!!

The gap increased on all 4 of them.
The gaps had increased to 0.055 on 2 of them, 0.045 on another, and nearly 0.060 on another.
I re-set them hoping to get another 3k out of them at least.
Not that it was running bad or funny, but it can't hurt.


The one thing I did notice(beyond needing to re-gap) is the plugs look dirtier than the iridiums did.
Most of the plugs are fairly sooty, except for the 1st 1/8-1/4 of the plug.
That area looks almost perfect.
Might be from the high RPM riding I have been doing... dunno.



Looking at the center electrode, there is a fairly large area that is COMPLETELY clean(ie. SHINY metal), a bit under 1/2 of the center electrode.
 
Comparing these modified d8ea's to a set of ran, but non-mod'ed d8ea's, these have a WAY larger "contact" area the spark hits.
The area the spark is hitting on the center electrode looks like it is being melted away almost.(rounded, instead of a sharp corner)
But I see no "slag" or anything, just like the edge of the center electrode nearest the arm is rounded off now.


'eh oh well. It runs well, so I really don't care a whole lot.
Might be a good use for old spark plugs when you are tapped out for cash, and want to keep riding though.


l8r

[78CB750CAFE]

I believe you can get Irridiums in both resistor and non resistor flavors

I have run the dR8eix (the resistor styleeee) for almost 2 years and love them (just got 12 more off of ebay $22 for set of 4, VERY good price)

[Soos]

I believe you can get Iridiums in both resistor and non resistor flavors

I have run the dR8eix (the resistor style) for almost 2 years and love them (just got 12 more off of ebay $22 for set of 4, VERY good price)

Those are the ones I was running.
22 for 4?
Thats not too bad!
I paid a bit under 30 for mine through a local auto parts store.


l8r

[MJL]

Seems to be a fairly common mod http://www.instructables.com/id/Save-Gas-And-Incerase-Horsepower-By-Side-Gapping-S/
Anyone got any first hand experience? would this change the temp of the plug - richening or leaning the mixture?

It shouldn't change the temperature of the plug. That is determined by the length of the insulator of the center eloectrode.  Longer insulator=hotter plug.

[ev0lution7]

isnt a D8ES is a NON resistor plug???

cant you get a D8Eix??

[78CB750CAFE]

I believe you can... google search NGK or Denso Irridium.
I run the dr8eix because I have 3 ohm Dyna coils and Accel non-resistor wires

[Trevor from Warragul]

I sidegapped the plugs on my 350/4 & Morini 3 1/2.  Stops the plugs fouling.

[Soos]

isnt a D8ES is a NON resistor plug???

cant you get a D8Eix??

Yes d8ea is a non resistor plug(aka a motorcycle plug) however when I asked for d8eix plugs, I was told by the sales guy they didn't make them.
There may be iridium plugs that are not resistive, but I have yet to find any that will work with my cb650.


Anyone come across a set of iridium plugs that are not resistive??



l8r

[Frankenkit]

can't we just use non resistive caps?

[HondaMan]

My 2 cents on the plug mods I've tried:

Keep in mind on the swirl-charge engines (CB750K0-K6), you are igniting a swath of flame, not a single point like in a hemi head (500/550, 750F). Wedge engines, like most V-8 heads, also ignite a moving charge.

In turbulent-charge engines (e.g., 750K0-K6), smoothing the interruption where the mixture passes across the spark can make for a better burn start. If you file/grind down the thickness of the ground electrode at the tip, making it into a thinner, rounded outer profile, even on the U-groove plugs, will help, especially at higher RPM. Also, indexing the plugs so the electrode "points" toward the center of the chamber will help ensure the mixture passes over the event in a more undisturbed flow, encouraging ignition. Using higher-output coils and a correspondingly wider spark gap will also ensure a wider flamefront.

On the 500 (I didn't race any 550 engines) hemi design, indexing the plugs so that the arm of the electrode was on the intake valve side (i.e., gap was on the side toward the exhaust valve) helped midrange-to-9000 RPM torque on bikes with Yosh pipes (roadrace megaphones). The apparent effect was that it stopped the extra burn of the overlap cycle somewhat, saving it for the cylinder charge instead. We did not take the time to look into the 'why' further than that, though. Changing the electrode shape on these engines (like on the 750) didn't seem to make any other differences that we noticed.

[Soos]

can't we just use non resistive caps?

yeah.


I know there is a thread somewhere on a member here doing that to a stocker set.

I believe he unscrewed the innards of the spark plug boot out took out the (?fuse?) widget in there that makes it a resistive boot, and replaced it with a wire(?) or some thing of that nature.





l8r

[Soos]

Oh wow.


I just read a page describing side gapping the plugs, you should check the gap at a 45degree angle between the two electrodes, and set it at -0.010 under normal.

I might re-gap mine just to see if there is a difference or not.
I have mine at about +0.014 over stock right now measured on a 45 degree angle.




l8r

[fuzzybutt]

hmmmmm i run solid core wires and d8ea's

[cbr-eric]

might be something I try, even though it is yet to be on the road   guess I could see if the idle improved..

[Soos]

Ok just re-gapped the spark plugs to 0.010 UNDER stock specs.

Got rid of the 1 thing that had been bugging me since putting these in.
The "stutter" when cold when I go WOT(CV carbs mind you) from an idle under 2000 rpm.
When it was warm it didn't present itself.
But cold it was a beeeeeeatch.


Looking forward to a high RPM highway report soon. Hoping to have lost nothing and gained low RPM reliability.
Thinking I might want to re-evaluate my advance now.(timing plate or the timing advance curve... hrmm........)

A wider gap essentially retards the timing, and a narrower spark plug gap can essentially advance the timing of when the spark presents itself in the combustion chamber.
I just went from +0.014 over stock gap to -0.010 under stopck gap on these spark plugs.
A change of 0.024 narrower.


Anyone think I need to retard things a bit(mabey 1-2 degrees?) to get it back where it was?
Or is that just not worth the effort?




l8r

[Soos]

When I mean stutter, the bike would kill itself at times.
When it was 1/2 way warm, it would bog/hesitate until past about 2200rpm, and then scream like a banshee to 10k.

When warm, I didn't notice it at all.



l8r

[cbr-eric]

what are you doing flooring it when it was cold??   and how are you guys adjusting the advance, like whats a baseline?   also curious about your highway speed results, nice to hear the effects you had on the low end

[Soos]

I can either program a different advance curve(for the dyna2000) or adjust the timing plate to either advance or retard the whole curve.

I like to "torture test" my bike to simulate a idiot on it.(or to see if the engine response has improved)


It's not nice(and I try to avoid it), but sometimes you need that clean acceleration from low rpm.
To avoid the fools on their cell phones mainly......




l8r

[Soos]

Ok after today, I think it may have helped the top RPM a bit as well, clutch seems to be slipping again over 8000 rpm.
It was slipping at the beginning of the year, so I adjusted everything.
Had gone away after that, until now.

I took her for a canyon drive in provo canyon to american fork canyon.
Everything is fine, until 3rd and 4th gear at 8k+ rpm's.
1st and second though, no slippage at all.
Mabey just getting to the point where it takes so much more HP/torque to accelerate and the clutch can no longer hold it together.

The motor whirrs up to 10k, but the speedo SLLLLOOOOOOwly climbs up.
I haven't a place to get a 5th gear test at that RPM range....





Mabey it's just my clutch finally giving it's last days(still stocker/original plates), mabey it's just time for some heavier springs. Who knows.



l8r