Question: I basically have a 2003 Arctic Cat 300 4x4 was a 250 but swapped motors with a 98 King Quad. The 250s carb had a jet break off down in it so I pulled one off a 220 Kawasaki figured wouldn't hurt much on the 250 but will it deliver enough fuel for the 300? Or do I need to order a jet kit? 300 didn't have a carb on it when I got the KQ for $100.

 

A lot more to it than just supplying the fuel, it has to mix with the proper amount of air at various rpm to make it run correctly. You might get lucky and have it run but probably not very well. Piecing together odds and ends can be a fun project but not if you going to do any serious riding and expect any reliability.

 

with my luck a brand new 4 wheeler wouldn't be reliable lol. It's more of a fun project n learning experience. Know more bout Atvs n Suzuki motors than I did few months ago. Surprisingly it does run n not to bad but can tell it doesn't have all the power it should and when you rev on it there'll be some black smoke and wants to fall on its face sometimes when you gun it. Physically the carb is the same size as the 250s n brand. The 300 KQ used a different style due to its fuel pump but both are 30mm to the intake tube. I'm assuming the 300 AC used same carb as 250 just bigger jet or jets.

 

Go to K&T Parts House and down load a parts manual for the 300 AC. It should show the jet#'s in the break down of the carb. You might check "JetsRUs" for 1 or 2 sizes bigger pilot jet and get a few main jets 1 or 2 sizes smaller to 1 or 2 sizes larger. Alternatively get a DynoJet "Stage 1 kit , try eBay. That adjustable needle and spring are excellent, just don't lose the C-clip or the shim washers, they are small, and the C-Clips can fly off about 10 feet if not careful. Might even drill out the slide. I drilled both of mine:AC 400 and AC500. I've never driven the 300, but I'll bet once you get the carb tuned, she'll be zippy. After doing the Stage 1 kit, drilling my slide and ended up setting the needle 1 clip lower than Dynojet suggested, the little 400 hauls azz! From barely hitting 50 mph, to almost pinning the speedo 57 mph on gps. It will easily lift the front tires 2nd to 3 gear shift. If you can't make it right, may have to find an original carb off eBay. Do some research before drilling the slide. 1/8" worked great for both of mine, but... Also, you could be right, once you get it right old Arctic Cats are very reliable.