I have a 1970 Triumph Tiger (TR6R). I haven't been into the carburetor for 10 years, so I pulled it apart to clean, inspect and clear the idle circuit. I had this a new chrome slide installed 10 years ago. It has performed faultlessly since then. I found that it had a 106 needle jet installed and on reviewing the service manual found that the specified needle jet is 107. As I said, it starts easily and runs nicely with no coughing or stumbling. The spark plugs are a darker brown than the tan color I would want, suggesting a dry carbon buildup. So I'm thinking it may be running a bit rich. I could adjust that with the air screw. The needle clip is on the center (2nd) notch. I would think that the 107 jet would make it run even richer. Anyone have any thoughts on how this carb is or should be set up?