Adjusting the mixture screw

very,VERY hard to read plugs with todays gas......i wouldnt bother. the way to tell if the air is set correctly is to warm the bike up to operating temps. this is not done in the driveway.....you need to ride the bike 10-12 miles to get it there. now while running crack the throttle, if it stumbles or pops, back the screw out a bit......dont over do it here, as your fuel mileage will suffer....

i would start with 2 turns out......then adjust a bit at a time. ride about a mile then try it again. good luck with it and let us know how it does...

Can you tell me what size jets you installed? Also do you notice any carbon fouling on the plugs? You may be able to drop a size on the main jet and pilot jet. The EZ-Just will adjust the air/fuel mixture in the transition between idle and where the needle takes over but would have little effect on mileage. If the bike is running strong and not showing signs of a rich condition (fouled plugs, strong fuel odor from exhaust) then I would look at other culprits, such as binding brake pads or other things that can impact rolling resistance.

or things like

Weight
Wind resistance (windshield, lowers, tour pack big parachute deployed)

Older tires, underinflated
it's not all jetting...

I would try dropping down to the smaller 190 main jet.

the main jet also comes into play with the needle jet or needle
as the throttle is opened the needle comes up and at a
specific point it starts to allow fuel to come from the main.

At WOT the main is wide open as the needle is out
well almost 100% out and you can get all the fuel.

Yes the instructions are correct for our kit however it is possible that your engine/setup is not breathing to the level that would require the larger main jet suggested, thus your experiencing the lower MPG. Every bike is different and I've made every attempt to provide jetting on what I've found over the years to work well with my particular parts in the kit.

While true that the main jet is primarily in full use at WOT it is already supplying fuel around 3/4 throttle as the needle rises and transitions midrange to the main jet circuit. The pilot jet on the other hand only delivers fuel at idle and the moment the throttle is cracked the needle takes over. Typically the only time a pilot jet would contribute to lower fuel mileage would be if the rider were idling for excessive amounts of time, such as in a parade or extremely heavy traffic.

Based on the information provided I would install the 190 main.

Or picked up a "ahem" larger riding companion at a bar.....

No installing the larger main jet would only add more fuel... not the direction you are seeking.

An 09 Nightrain will naturally get better mileage due to it being lighter, fuel injected, and 6-speed which keeps the RPMs down. However I would still check the plugs to make sure you are not running overly rich. Other fuel related culprits include the choke (enricener) not fully closing or an intake leak around the manifold causing the need for additional fuel to compensate.

If your plugs are not fouled and the other things mentioned above are eliminated I would turn my attention toward binding brakes, wheel bearings, or a slipping clutch, all of which are common causes of low MPG.

the v-ducter is a great addition to a bike that is tuned correctly. it wont help you if the bike is not preforming. adress the other problems to get the bike running right, then add the v-ducter. i would check the enrichner for closing all the way, and intake leaks.....use some wd 40 with the red tube to spray around intake, with the engine running, avoiding the inlet on the carb. if the rpms change, you have a leak. not getting the carb/intake o-ring just right happens a lot. make sure the lip is not folded. let us know!