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You guys told me to check my plug - you tell me..

5092 Views 21 Replies 12 Participants Last post by  scuzz
I think it looks alright... maybe a little lean.

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That looks good to me! watch the ceramic insulator...A light tan color is good, Black and it's too rich, white soot means its too lean. if you have the controller and spare plugs, you could teak it a little( maybe just a touch richer) and just monitor the plugs and by the seat of your pants. If this were carberated I would leave it be.
hmm... well I guess its running alright then :)
When in doubt...Google. :)

http://www.dragstuff.com/techarticles/reading-spark-plugs.html

Reading For Air Fuel Mixture

The porcelain around the plug’s center electrode can be divided into three areas for reading. The area that is closest to the tip is affected by the idle and transition circuits carburetor circuits and is of no real concern to a racer. If this area is gray then you drove the car back to the pits and you cannot correctly read the plugs. The middle area is only colored when you drive down the road at around a steady 30-40 mph and is normally affected by the primary circuit jetting with the power valve closed and this is really of no concern to the racer. The area you are interested in is that third that is all the way up inside the plug where the sun don't shine. This area is colored when all is wide open under full power because the combustion chamber heat totally cleans off the other two areas. It will take a special plug reading flashlight with the magnifying glass to view it correctly. Plugs cannot be correctly read by just quickly looking at them with the naked eye. You see people doing it all the time because they do not know how to read plugs.
Normally aspirated cars should have a light gray or tan hydrocarbon ring or as some call it a "fuel ring" all the way up inside around the third area closest to the point where the porcelain is attached to the metal jacket of the plug. The actual color may depend on type of fuel you use. This fuel ring should appear like a light shadow. Most VP C-15, C-16 or C23+ fuels will show as a light gray when correct. This fuel ring starts to color on the porcelain side that is below the ground strap and works its way around either side of the center electrode until it completely joins. Sometimes it may take two or three runs to see a good coloring. Note: New engines or engines that pump a little oil may show a thin oily line way down inside on the porcelain where the porcelain meets the metal wall of the plug. This oil line has nothing to do with the air/fuel mixture but may be confused with the fuel ring you are looking for.If you are having a hard time figuring out if what you are reading is correct or because you are not sure if the plug heat range is correct then tow the car back to the pits and drop the headers and look inside the pipes. If they are black then you are too rich, if they are light gray or white then you are too lean. The pipes should be a medium to dark gray or tan color.
Normally the white area of the porcelain has a chalky appearance. If you see the porcelain take on a shine then it is time to change the plugs because the glass that is in the porcelain has been melted and has glazed the surface. If the car has been running rich (due to lots of idling or incorrect fuel mixture) then it is possible to glaze the plugs and short them out during a run because of the sudden heating of the plug with the soot on the porcelain. This glazing appears to be a glossy coating on the porcelain with a splotches of color of greenish yellow or brown. These two different glazings will cause the plug to short out and misfire and raise ring lands or make a popping through the exhaust when going down the track.



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So its burning fine huh?
I'd say it's a tiny bit lean, but it's really hard to tell by the plug anymore with the additives in fuel today. It's not bad though.

Also, with what procedure did you do the plug chop?
I'd say it's a tiny bit lean, but it's really hard to tell by the plug anymore with the additives in fuel today.

Also, with what procedure did you do the plug chop?
There's a procedure? :lmao:

I just pulled it out and took a picture of it.
That won't work. You have to get the bike wide open for as long as possible (atleast 200 yards or so) and then pull in the clutch, kill the motor, and come to a stop.

Your motor will most likey give a richer reading if you're just 'putting' around or idling. So it's possible you're a lot leaner than that.
Oh... yeah it was cold when I pulled it. Damnit... gonna have to wake the neighbors... brb...













haha, jk... i'll try it out tomorrow if it warms up.
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plugs are cheap anyway ...get a box of them and fire away lol
plugs are cheap anyway ...get a box of them and fire away lol
Yeah, but pistons aren't.
huh?> youre gonna foul a plug up and the motor will be noticeably more sluggish/unresonsive waaay before youll destroy a piston... its operator error to keep it hammered to the point of burning a hole in a piston. Ive never destroyed a piston due to a rich or lean mixture ... we aren't talking about carbs and poor jetting... now if you had a 12:1 piston ... maybe ..not stock though.

you can get odd-colored plugs from any number of factors aside from a rich/lean mixture ... #1 reason is bullshit gas from the pump. Even "premium grade" from the pump nowadays is horseshit ... gas with 10% ethanol is horseshit... humidity ... age of gas... oil condition ... even ambient air temperature and altitude.

truth is ..if youre planning on tuning your quad .. go spend some money on some 110 octane ..it not only is good gas ..your quad will run much cooler giving you a much longer window to dyno youre engine @ redline before causing any damage based on heat.

once you have your power commander dialed in with 110 you can enrich your map 1 or 2 pts for the days you are using pump 93 octane.
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honestly, yeah, that procelain looks decent, but that white on the electrode, i wouldnt be too happy about, i wlaways make sure the whole damn thing is golden brown, it looks to me like you are running lean wide open and rich at idle ? you will figure it out, just dont hold it wide open for long until you're positive it's correct...

when you are checking your mixture you ALWAYS start with a brandy new plug, i even go as far as to warm the engine up then swap the plug for a new one, pull out and fly down the road in about 3rd gear wide open for a few seconds, pull the clutch, hit the killswitch and come to a stop without leting the clutch out, once stopped, then check your plug...this is the most accurate way, what everyone prior has said is correct, but you have to start with a new plug for sure !!!

probably a good idea to clean and oil your filter before checking too, you prob know, but if your filter is clogged by too much dirt or oil it will run richer and if its dry or ripped it will run leaner...

good luck !!!
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If you have the money your best route would be have the a/f read on a dyno. Sounds like there are a lot of variables when reading a plug. Did you ride it full throttle and shut down right away? I read you need to do that in order to get a proper reading like scuzz posted. Not too sure though
If you have the money your best route would be have the a/f read on a dyno. Sounds like there are a lot of variables when reading a plug. Did you ride it full throttle and shut down right away? I read you need to do that in order to get a proper reading like scuzz posted. Not too sure though

yeah, you have to shut it down at wot, because if you pull it at idle, you will see what your mixture is at idle ya dig ?
looks lean at an idle to me.

you have the commander just do one click richer on the bottom, i bet you will feel a difference :D
That plug wont tell you anything, you need to do a plug chop on about 1/4 throttle, 1/2 throttle and WOT. You need to use a new plug for each chop and make sure the quad is all warmed up. Once warmed up install the new plug, go through to 3rd or 4th at 1/4 throttle for about 30 seconds and then pull the clutch and kill it, remove the plug and look at the insulator part only, repeat for 1/2 throttle and WOT. That way you can check most of the curve for correct A/F ratio.
Just drive the hell outta it till it blows then you will know for sure:lmao::lmao::xx:
:thanks: I have been saying to check them this way for a long time.:tup:
I also check at 3/4 throttle also. they have a lot of adjustability in the fuel controllers.


That plug wont tell you anything, you need to do a plug chop on about 1/4 throttle, 1/2 throttle and WOT. You need to use a new plug for each chop and make sure the quad is all warmed up. Once warmed up install the new plug, go through to 3rd or 4th at 1/4 throttle for about 30 seconds and then pull the clutch and kill it, remove the plug and look at the insulator part only, repeat for 1/2 throttle and WOT. That way you can check most of the curve for correct A/F ratio.
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