Spark Plug Reading

[aflythe]

Hey all, I'm not the best spark plug reader, and I wanted to get second opinions. I know, or at least I believe I know, that dry black sooty means rich, but why is the bottom of the plug rich and the tip clean, it's not really white, rather bare, clean metal. I cleaned these old plugs before putting them back in the bike so it could easily be that I didn't clean the bottom well, but I've run over a tank of gas in the bike after cleaning them. Have I not ridden it enough to have the plugs change color? I was going to be adjusting the mixture a little bit and I have new plugs for it now, but I wanted to put them in after the tuning was done. My gas mileage seems to be lower than 45mpg so it being rich makes sense, I know the idle is rich (10 on AFR reader). Thanks in advance for the help!

 

[zed1015]

The base ring is mixture/jetting and the ground strap is heat range.
The base ring should have a light turn of soot and the ground strap a tan colour which darkens on the bend towards the base ring.
Your plug looks to be in the ballpark and maybe slightly on the rich side unless you have other issues involving oil burning which will also darken the plug.
Bear in mind that unless you have done a high speed chop the plug reading you have only indicates running conditions at idle on the pilot mixture no matter how far or hard you have ridden.
If after having come to a normal stop you feel you have an excess of soot on the base ring that is solely due to mixture strengh then lean off the pilot mix a touch.
All this assumes that you have a clean air filter etc that isn't causing any restriction which will also affect the A/F ratio.

 

[aflythe]

The base ring is mixture/jetting and the ground strap is heat range.
The base ring should have a light turn of soot and the ground strap a tan colour which darkens on the bend towards the base ring.
Your plug looks to be in the ballpark and maybe slightly on the rich side unless you have other issues involving oil burning which will also darken the plug.
Bear in mind that unless you have done a high speed chop the plug reading you have only indicates running conditions at idle on the pilot mixture no matter how far or hard you have ridden.
If after having come to a normal stop you feel you have an excess of soot on the base ring that is solely due to mixture strengh then lean off the pilot mix a touch.
All this assumes that you have a clean air filter etc that isn't causing any restriction which will also affect the A/F ratio.

thank you, the AFR kit I installed told me I had about 10 on the idle which is rich, the needle seemed to be 11-13 somewhere in there, and if i got to wide open then it was 12 which everything looks good except for the idle obviously. thanks for the help!

 

[gtem]

That looks like a decent plug color to me. Does it smell "gassy" at idle? What's the throttle response like from a roll on at low rpms?

 

[KiwiAlfa156]

Plugs (if not run for too long/old) tell you what what was happening when you killed the ignition. So think of them as a snapshot.

I found this useful re: plug reading
https://honda-tech.com/forums/forced-induction-16/***-basics-reading-spark-plug***-3063102/

If it were me, on the AFR readings I'd screw the fuel screws in ⅛ turn in and see what that does on a fully warmed engine. Keep adjusting and testing until the numbers are a little leaner and more importantly off-idle throttle response is as good as it can be.

I realized a while ago that getting the mixture just right on a closed throttle with correct fuel screw settings as more than just 'setting the idle mixture'. It's not really about how smooth it is when sitting at the lights idling. It's about every time you are winding on from a closed throttle while on the move, which apart from highway cruising is a lot.