dont need to pull the plug out, pull the lead off, slide an appropriately sized screwdriver into the lead, holding it by the plastic end (you'll know if you dont) about 4mm off a good earth crank the bike. Does a spark jump across to the earth when its going well?
if yes do the test again when its not running
if no check its a good earth and screwdriver is inserted properly and repeat.
when test is done when not running
if there is spark forget electrical, check your plug and carb.
if no spark its electrical, check as per previous post with service manual.
after previous post if its electrical find a sparky or someone who knows a bit about auto elec (very basic knowledge is all)