To read the condition of spark plugs propper, is a knowledge for itself. :)
Here you can finde some possible spark plug-conditions.
Hopefully it will help you to "read" what´s up with your plugs and your engine.

Notice that such plug-conditions don´t appear immediately!
Plugs must be in use for quiet a while before you can read their performance.
Also your riding-habits have an influence on the spark plugs.
Short distance rides i the city will let the plugs look different
from what they look after long distances at high-speed.
So to the plugs "carefully".

Gray-Brown deposits, lightly  coated core nose.
The engine is adjusted right, Plugs fit to the engine propper, Engine is in good condition
The old light-brown color of former times will disappear more and more due reduced gasoline-additives.



Electrodes apperas glazed, core nose is very white.
Eventually wrong heat range of the spark plug (to hot)
Hint that the fuel mix is to lean! Check ignition timing.
Maybe gasoline with to low octane-rate.



Sooty, dry and black deposits
Hint on to rich fuelmixture. Check also ignition-timing.
Maybe spark-plug with wrong heat range in use (to cold).

Carbon Fouling


Wet and oily deposits, wet and oily electrodes
The reason could be worn out pistonrings and/or bores.
Also worn out valve guides and valve stem seals could be the reason.

In rare cases plugs could look like this due engine break in.

Öil Fouling


Crusty, light-grey sandy deposits build up through gasoline- and oil-additives.
Also a hint on defect valve guides, valve stem seals and pistonrings.
Also cuased by idling for long periodes.

Heavy Deposits


The plug insulator firing tip apperas yellow or green/yellow and shiy.
Caused by wrong carburation, excessive idling followed by hard acceleration.
Also check ignition-timing!

Lead Glazing


Burned away electrodes. Core nose has burned glazed appearance.
Hint on pre-ignition. Check ignition-timing!

Electrode Damage