I was wondering what the difference between the round style jet that is in a Cat quad, and the hexigonal ones that are in other rhings, are they interchangeable??? Thanks for any help.

 

They are NOT interchangeable. The hex jets are for Mikuni carbs. Your Cat has a Khein carb. (did I spell that right?)

 

My 454 has a Mikuni carb. I tried to adjust the carb as suggested on another thread but was unable to loosen the screws on the float bowl. I tried everything but they would start to strip everytime I tried to turn them. Any suggestions?

 

See if you can use a small pair of grips, order new screws for it.

http://www.brownsleisureworld.com/Parts/ATV/1998/1998ATV5004x4(98A4G-1998)/CARBURETOR.htm (will be the same as yours if its a 34mmBST)