Try a #100 main jet (stock is #95). Then put your needle clip 1 spot down. Also, turn the pilot screw out an extra 1/2 turn. This should richen it up enough for your pipe.
I have a DG pipe on my 185s and these settings work great with it.
1981 Honda ATC 185s
-DG Exhaust
-200x Carb
-Uni Filter
-Air filter box removed
-10T Front Sprocket
-Plastic fuel tank
-Aftermarket seat
-200s front forks/shocks
-Aftermarket 4 bolt rear wheels
-Tire chains when ice riding
1988 Ford Mustang LX 5.0L
-Wayyyy too much to list!!!