As we have only confirmed compatibility of this carburetor with the Baja Motorsports 90 ATV, Canyon 90-U ATV, Wilderness 90 ATV, and Wilderness Trail 90 ATV, and those have 4-stroke engines, it would be unlikely that this carburetor would work on a 2-stroke engine.
Will this work on a 2004 arctic cat 90 cc 4 stroke?
We are unfortunately unable to confirm compatibility with that model, we have only been able to confirm the compatibility with some Baja models. It may possibly work on your Arctic Cat, we'd recommend comparing the images & specifications on this item page to the specifications of your existing carburetor to see if they match. If they do, then this should be a compatible replacement.