G16 carb help

[Tsmall114]

Hello, I recently bought a 1996 g16 that was in good shape just been sitting for few years. I replaced battery, cleaned cab, replaced fuel lines which were cracked, changed oil and fuel and it popped right off. The original owners said the muffler rusted out so they made there own out of tubing and a small screw on muffler, looks like a snow blower or lawn tractor type. A anyways onto my question, we put a after market cluth and springs on, 3 inch lift bigger tires and wheels, ran great but loud of course. We just bought a kit the came with new air filter , spark plug and carb jet. The original jet was a 86, this one is a 86.3. Put the jet in and throttle response was way quicker, low end way better but it's running rich. Plug is black, and I know it's not getting enough air kuz if I stick the air filter in, then it barely idles and just won't run, remove it and runs fine u until top end seems like its loading up or something? I removed the governor and cable goes straight to carb no back firing. Is there anyway to lean out the carb a little? How do you guys with aftermarket carb jet tune it? I have drilled some holes in the air box but maybe not enough, we use this cart at the race track to pull my car to the starting line and back to the pits. Like I said it has alot better throttle response and torque is alot better after this jet but only without the air filter In, and I'm worried if I buy a aftermarket muffler now that the added back pressure will just make it run richer and I haven't found anyone having trouble once they changed jets on the Internet?

[DOOmsman]

[DOOmsman]

Stop drilling holes
The improved take off is the springs and new clutch
Try going back to the stock jet and tape the holes.
This is assumtion that you did several things at once.
If so TSK TSK TSK you know change one thing and test.
We want pics cart, race car and dog.

[LURCH]

If you bought Plowmans filter and jet kit you do have to mod. the air filter box. 5 1/2 holes on the back side with the box mounted and with a hole saw drill the funnel part that the carb. adapter bolts to and like a 1 inch pc. in the middle of the air box. I have posted pic's on here before just do a search for my post you should find them. These mod's are per Don @ Plowmans.

[Tsmall114]

Sorry I should have specified alittle better, I did all the clutch mods before, after we got it running when I bout it, the clutch was shot so we replaced clutch and springs, and drove it that way for awhile with the lift and bigger tires, it was a dog down low and hesitated from a dead stop. The kit we bought was from carts parts plus, just and oem filter for now.