Yes , light tan is optimum. But its preety hard to get a decent reading on your plug these days due to poor fueling.
My crf50 runs good but the plug carbon's up extremely quickly. I have the mixture screw at 3 turns out and my clip is in the centre slot. I droped the needle clip down to the 2nd last slot but it ran like ****. Thing pop's abit when the throttle is backed off at high rpm but thats expected as fuel is cut off and there for lean's out. But can't seem to get rid of this excess carbon on my plug , perhaps a smaller main for my 20mm (88cc)?