I'm getting g new spark plugs tomorrow as mine are pretty bad so iv just finished re building my carbs and before syncing them I wanna see if it's running rich, lean or just right so how long do I need it running before I can check the spark plugs
A couple of Km under load will usually be enough to get a reading. The true colour of a plug is at the bottom of the porceilin where it meet with the metal, not at the exposed tip.