sandeepcf

I am running Honda Unicorn. The spark plug is 1800 kilometers old. The color of the porcelain has changed only on one side as you can see from the picture. I don't think its normal Is it? Does my spark plug look healthy? Please analyze it and give me tips. Am I running too lean?

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Aryan

Query Approved.

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jd666

looks fine to me. did u get the gap checked??

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rennycornelius

It looks slightly cooked, your mixture may be on bit lean side.

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suresh6270

the electrode seems white in colour.....its running lean.......
After a good run at high revs it should be brownish red....

anmol_1990

its lean, make it to richer side as it is good for new engine

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sandeepcf

The electrode is white on one side and brown on the other? what explains this?

RKOLI1983

According to my 2 cents that means that the flame-front/the flame which is born when mixture is ignited goes a bit sideways instead of going straight down towards the piston. Which is why there is a small area around the electrode where the combustion is occurring at a lower temperature and pressure and hence the deposits of incomplete combustion accumulate on one side. This could be because of anything ranging from uneven turbulence in the combustion chamber to eccentric sparking.

sandeepcf

Today I increased the gap of the spark plug in my unicorn from stock to a little bit more. I observed an increase of power, also the sound of the silencer changed(more noise but much crisp). I rode for 5 kms and noticed that the engine became hotter than normal. I opened the sparkplug and noticed that the side/lateral electrode is blue in color. Can I run this setup or will it cause any damage? because I love the feeling of the bike with the increased gap.

And how does the gap effects the combustion and performance?

recommended gap - ?
smaller gap - ?
bigger gap - ?

psr

You seem to be running a lean AFR. The coloring of one side brown and the other white,is because the side facing the inlet valve is cleaned with Petrol spray on each suction stroke and hence looks clean and white,while the side facing the exhaust valve remains slightly colored. Remember to make the AFR slightly rich,or your bike will run hot and engine wear will be more.
Increased plug gap increases the size of flame Kernell and hence the difference in the response and sound......but the firing will become retarded,and will make the bike run hot.
Make the AFR rich.