[ngoma]

Might have to experiment several times, turning another 1/8 turn in each time. When it starts loading up with too much smoke and no real improvements you can turn it back out 1/8 or a few 1/8's to find the happy spot.

The no-tamper collar is a nuisance but you should be able to get it loose enough to make the adjustments to the fuel screw.

To really know what is going on with the MPG you need to do the math at each fill up. Miles driven since last fill up, divided by gallons. Must fill up to same level each time (when liquid fuel is visible at the same spot in the filler neck) and really only accurate over several fill ups. Keep track of it in the small notepad you keep in the glovebox that you use to track oil changes, tire rotations, air filter changes, brake pads, timing belt, etc. When you start seeing a trend with the MPG you know something needs attention.