114 was the original main jet size. I'm running a 116 main jet in Iowa. The 118 might actually be too rich depending on your elevation and causing the bike to run crappy once you're into the main circuit 33% to 100% throttle range. Especially if you have the needle shimmed up a bit you might experience an overly rich main jet circuit that acts like trying to drive with the choke out slightly. Or you might be totally OK. I'm not sure how quickly the carb fattens out and starts to act up.
What brass plug are you speaking of that you removed? I have not removed anything from my carburetor, or do you mean the anti-tamper cover over top of the pilot jet adjustment screw under the carb? If so, I am running my carburetor at 3 turns out of that screw.
Fortunately nobody had ever taken my carburetor apart. Another handy test is to check fuel height using clear tubing out of your fuel drain on the bottom.
Loop the tubing up and see how high your gasoline sits in the float bowl (with the bike upright.) It should be sitting at 8mm below the lip on the float bowl. If it's lower or higher you adjust your float to compensate. The bike runs great when fuel height is set dead on. This measurement is more important than measuring your float height.
Your pilot jet should be a 40 size. I tried a 42, but it didn't help me. 40 works great for me.
I have to start my bike with varying amounts of choke and then I can go off choke completely on even cold days at about 1 minute of driving.
I have a smooth transition from idle to wide open throttle and my settings are: 40 pilot jet, 3 turns out on the pilot screw, 116 main jet, and about the equivalent of 1.5 mikuni carb shim washers. I made mine out of pop can pull tabs because I'm a tight wad.
My bike is a '93 so the carb is identical to yours. When I got my bike the rubber intake boot to the engine was cracked and was leaking air. I had to buy a new one. I sealed the old one and it worked, but the new one is ideal. Check for air leaks since they like to crack or come separated from the metal part.