2003 arcticat 400 4x4 wont rev past quarter throttle
 

Hi, I have a 2003 arcticat 400 4x4 automatic. My issue is that it will only go to about 25mph then begin to sputter and pop, also makes a clanking sound. I have cleaned the carb 3 times! Had an air leak but i put new hose on. Checked the fuel line, seems to have good flow. It's an automatic but sometime it will shift into gear hard. It does the same thing with the throttle in low and high gear. Im completely lost and have no idea what to do! Thanks for any help!

You might pick up a Dynojet stage 1 kit on eBay. Follow their advice, but it sounds like either your main jet is partially plugged or way too small. Just for giggles, remove the gas tank, dump the contents into a clean white 5 gallon bucket. See how clean or dirty the gas is. Put an inline gas filter when you reinstall the tank. Both of my Arctic Cats gas tanks looked like mice had lived in them, before I cleaned em, btw. Once I got my AC 400 sorted out, it really screams 57 mph.

When was the last time you checked your valves? Could the clanking be valve chatter?

Good idea! Ill put that on my list of things to check.