vegasdave,if you have 30mins to waste try moving the needle clip up 1 slot closer to top/bunt end then installing a thin spacer washer under the needle clip.
Doing that will effectively /ever so slghtly lean out your cruise mixture just a tad (1/2 step not full slot step) which i have found in most cases isnt enough to make the bike run too lean but doing that could maybe inc your avg mpg from your current 36-40 to 40-44+mpg.
Let us know what what that did for your mpg if you decide to try it out someday.
Sorry, but for some reason only quick reply works for me
Any way Scott, if you have ever read the Mikuni 42hsr carb
tuning manual, it does state that moving the needle up or down has no effect on cruise mileage below 70mph:
Poor milege at these speeds can
be corrected by fitting a leaner
needle. Raising or lowering the jet
needle has no effect on fuel mileage
below about 70 mph.
and I see no reason why this would not hold true in the stock carb. And I did try this out on my 42, Mine is set on 2nd groove, usually I would get 40mpg at 80mph, going to the 1st groove was up to 45mpg, and this was done on a few tanks and checked a couple of times, my 65mph cruise stayed the same mpg (50) in both clip positions. But at the same time, clip position will affect acceleration performance. For the 42 carb it is the needle that effects mpg at cruise, that is the straight portion, just above where the taper begins, the 42 has 4 needles specific to this carb, all the same length, but it is only the cruise portion of the needle that changes needle to needle, and is only .o1mm difference from needle to needle. but in my experiments between the standard 97 needle to the leaner 98 needle, without changing the main
jet, pilot screw, just swapping the needle only and using clip in same groove and doing a 65mph 100 mile run, I picked up 8mpg, consistently.
It doesn't take much throttle twist to eat gas, if the carb is set correctly.