Reading Spark Plugs

[slybonesjesse]

I have seen in a few older manuals for cars I have not had in ages, that you can tell the mixture and running condition of the engine by reading the spark plugs. The plugs are supposed to be a nice golden brown color. One question I have is how fast do the spark plugs adjust to conditions? Meaning if its rich running down the freeway and lean at idle, and I run down the freeway for a while, then pull over and it idles for a short time before I turn it off, or I have to ride easy into a safe spot, into the garage, etc -- Will the plugs have changed significantly from that little bit of light throttle position running and screw up my freeway readings? As part of my valve adjust I did today I changed to them Iridium plugs. Pretty much based on 2linby's inital posting of a mileage improvement. Unfortunately for me,I will be playing with the carbs next weekend at the wrench session. So I will not get a true gauge of the improvement the plugs alone could make. But while I have the plastic and tip over bars all off I am going to get my complete laundry list done. Valves and plugs this weekend, carbs, fuel filter, and throttle cables next weekend, and coolant/hoses next the following weekend. Along with and oil change in there. And the front fork oil too. Connie will be running naked this fall, at least for a few weeks. So here are some pics of my plugs. These are the stock DR8EA's just pulled out. 16K miles in them. Plug 1 http://home.comcast.net/~slybones/Concours/images/DSCN0365.jpg Plug 2 http://home.comcast.net/~slybones/Concours/images/DSCN0367.jpg Plug 3 http://home.comcast.net/~slybones/Concours/images/DSCN0369.jpg Plug 4 http://home.comcast.net/~slybones/Concours/images/DSCN0370.jpg http://home.comcast.net/~slybones/Concours/images/DSCN0371.jpg The only thing I thought was interesting was looking at #1 and #4. One side of the plug the inner part was still white like new, and the other side was colored signs of burning. I took 2 pics of #4. On the 2nd pic for #4 the color looks a litt1e dark. But that is exposure or shadow from the way I was holding it. Color looks like #3. So lets have some conversation about reading plugs. Anyone know anything about it. 2003 Concours, 56K COG #6953 IBA 28004 http://home.comcast.net/~slybones/Concours/connieMain.htm

 

[S Smith]

IIRC, plug coloration is more an average "reading" than instantaneous. The only instant reading would be an oil or gas soaked plug. You plugs appear to have normal wear and are not quite worn out... even the gap appears to be close to spec. -- Steve Smith, COG #3184 COG Northeast Area Director (somewhere in south central CT)

If you're not living on the edge, you're taking up too much space.

 

[conando]

I don't know if I read somewhere or someone told me, but to get a high speed reading accurately you needed to cut the ignition, pull the clutch, and coast to a stop.

 

[Ron Moss]

I don't know if I read somewhere or someone told me, but to get a high speed reading accurately you needed to cut the ignition, pull the clutch, and coast to a stop. + 1 That is the only way to get a true reading.

 

[S Smith]

Here is an interesting page on the NGK site about reading plugs... http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/faqread.asp -- Steve Smith, COG #3184 COG Northeast Area Director (somewhere in south central CT)

If you're not living on the edge, you're taking up too much space.

 

[suzukijay]

Here is an interesting page on the NGK site about reading plugs...

I have a pamphlet from the bike shop that I used to work at from NGK. It has ~40 pics of plugs. I'll have to dig it to confirm but if I remember correctly there were about 15 pics of spark plugs that were considered "NORMAL"

 

[Steve in sunny Fla]

Slybones, all your plugs look to rich to me. Generally with ethanol, I think plugs generally look a little lighter in color than regular gas did. My plugs are generally mostly white with a light brown area on the end of the insulator. Black on the end of the threads in generally from the idle circuit. Also, keep in mind that you're mostly running on the idle and needle circiuts, so plug reading like this doesn't reflect the main circuit - though the main jet does impact all of the needle circuit. Steve

 

[slybonesjesse]

Yeah, unfortunately I didnt get to them float levels this weekend at Colins. I was a pu$$y and didnt want to ride in the friggin down pour to get there. Which some people did. But I figure I commute that way day after day, why do I want to ride like that on the weekend too. So I drove the truck, hung out and ate some great grub, and stole some money off Colins kitchen table. Can't beat that. In any case, I think this way I'll get 4-5 full tanks on these Iridium plugs under daily commute and will get to see if there is any mileage improvement. I wasnt thinking I was going to be able to tell since I was changing more than one variable at once. But with the postponed float level change, I can get in a few tanks with the only change being the Iridium plugs. So far with the plug change the bike runs fine. The only thing I really noticed a little was it seems quieter. Not sure why that would be, but when I first rolled it out of the garage and fire up, I was thinking I must have done something wrong. Its kinda slight, but I could tell it was different sounding. After a test ride I was at ease as it runs and starts fine. Only other possibility is the valve adj. I changed the plugs as part of my valve adj. I used to run them on the loose end of the scale. .007 and .009. Most were still at the loose end. maybe a tad looser. Only one cylinder was tighter that last adj. Cylinder 1 exhaust. -- Anyways this time I went to .006 and .008. so they are all tighter that before. This could be where the quiet comes from. 2003 Concours, 56K COG #6953 IBA 28004 http://home.comcast.net/~slybones/Concours/connieMain.htm

 

[slybonesjesse]

Dont go reading anything into this. But last year when I first installed the SISF jet kit, I lost 4 mpg. Many claim 1-2 mpg increase. Dont get me wrong Steve and Colin both were great about helping me. No complaints what so ever. Steve was the one to say they looked rich to him, and these were removed and the pics taken turning that time. Since then Colin and I redid the carbs. I removed the shims from under the needles. There were some broken / ugly looking o-rings under the idle screws, we double checked everything. Put it all back together and everything is where it should be. My mileage as been back up where it should be, etc. All is good. Again no complaints in the support department. So whats the real point? Here are some pics if the Iridium plugs with everything running good and mileage what it should be. This is the only point. To show the difference in the plugs with poor mileage and good mileage. Thats it. Plug 1 http://home.comcast.net/~slybones/Concours/images/IMGP5201.JPG Plug 2 http://home.comcast.net/~slybones/Concours/images/IMGP5200.JPG Plug 3 http://home.comcast.net/~slybones/Concours/images/IMGP5199.JPG Plug 4 http://home.comcast.net/~slybones/Concours/images/IMGP5198.JPG 2003 Concours, 61K COG #6953 IBA 28004 http://home.comcast.net/~slybones/Concours/connieMain.htm

 

[Steve in sunny Fla]

I just reviewed the pics. the first rich set is typical of what i see when removing jets with stock carburetion. The second set is typical of what I see with my jet kits; the #1 plug, with the little brown area near the tip is the most typical. I will say that plug reading with ethanol is a bit dicey in that the plugs run pretty light, with less deposits than the old charts from "back in the day" would show. Steve