For mod #2 I need to explain that this will eliminate your chokes function, possibly making it difficult to start your motor in colder weather...If you do not wish to eliminate your choke then do not perform this mod below.
My next obstruction I've found is the entry port of the carburetor.
Air is hitting the sides of the extended port entry, helping create turbulent air flow...Simply grind this extension down and radius the entry until you have a smooth transition for air to enter.
Now keep in mind that I'm not porting the entry way what so ever and the entry port still measures 14mm or close to that but will improve air flow quite a bit given its size limitations.
Here is the stock carburetors air intake side.... you can see the extended tube like extension of the bore ,this extension blocks air creating a turbulent flow into the bore...This extension is there so the choke flap has a surface to completely close off the bore and only breath through the tiny hole creating a very rich mixture that helps start your motor in cold weather.
View attachment 79468
This is what it should look like after grinding down the extension and giving the entry port a nice radius.
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One more pic...notice how even the choke stop has been removed.
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For stealth looks you can leave the choke assembled or simply remove the entire choke assembly and fill the lever hole with jb weld or epoxy so no garbage or water can find its way through.
Other than tuning I wouldn't consider anything more needed to get the most out of this carburetor.
If you want a larger carburetor I would suggest going with the 16mm "Speed" version of this NT carburetor and follow the same mods shown here if you wish.
Edit:
Upon some discussion below on the subject of boring the carburetor..I may try this to see how far it can be taken without idling issues or difficulties to tune...I'd like to keep this a simple but complete guide to gain a little more performance out of your stock 14mm NT carburetor.
About that high flow airfilter, in all honesty using an aftermarket air filter would help perform better as air isn't just drawn in from the bottom such as with the stock air filter cover but more so drawn in from 360 degrees providing a better direct flow of air in general to the carburetor and, will have better filtering capabilities.
Thanks for looking.
Edit: More to come.