Changing a spark plug on a two stroke is super simple and something we recommend to do BEFORE EVERY RACE! It is a cheap insurance policy so why not?
Start by removing the tank for easier access to the plug. Once the tank is out of the way, remove the spark plug cap. Then grab the correct size wrench and loosen up the plug. Righty-tighty, lefty loosey. After the plug is loose, use your fingers to finish twisting it off until the plug is fully out.
After that, remove the spark plug gasket. Make sure it is clean, if it is go ahead and install on the new plug. To re-install you hand tighten it then take your wrench to tighten it up. Don’t go over board on over-tightening otherwise you could strip the head. But don’t leave it too loose otherwise you will have running problems. Once installed, put the spark plug cap back on. You should here it click once it is on all the way. Some people will wire tie their spark plug cap on. It is preventive thing and not a bad idea if you travel a lot!
Another thing we do is inspect the plug we took out. How does it look? Is it really black, oily, gasey, brown, white, gray, etc….? The spark plug tells the story and lets you know if you need to change something (jetting, air screw, oil) or if you may have a problem.
In short, changing the spark plug is a cheap thing to do to ensure the likelihood of fouling a plug is minimal chance and let’s you know how the bike is running!