Excuse my bluntness but, you can only judge the mixture by doing a correct plug chop. For mid range, a fairly straight slightly uphill road, constant just above half throttle for two or three miles. Clutch in kill the engine with kill switch. Coast to a halt, once in a safe place whip the plugs out and that should give you a clear indication of the mixture at that throttle opening. For the main jets same again only use full throttle. Idle mixture a bit more tricky, standard carbs etc generally run a tad rich at idle, a colourtune plug is handy to get near or verify the mixture.Thank you, Machine. And Pete (we crossed in the post). Ahem, where was I?
Quick test run, only eight miles, bike running well, apart from that poppin' and bangin' on closed throttle.
Took the plugs out and I'm slightly puzzled:
View attachment 166850
Don't know how to read these. Is the bike running lean? The centre electrode is not covered in white ash, it just looks clean. Well, these were new plugs about 20 miles ago. There's some soot around the edge and the curved electrode does have some whitish residue.
Hope this helps. You are not alone. My plugs look a bit pasty/pale but it runs and pulls OK midrange so I’ll leave them alone.