I have a 2002 Arctic Cat 400 4x4 (Green) that starts fine with choke and will idol without it. With the choke off it will idle and rev to about mid rpm range. If I give it full throttle it will bog down unless I have the choke open then it will rev until it tops out. It will not idle with the choke enabled. It has a 140 (5507-044) main jet with a slow #38 (5507-246) jet and I think a 90 starter jet. It should be mentioned that the carb, sparkplug, oil, and air filter are brand new. I can get it to tack out if I stand on the bike and shake it too.

 

OE carb or Chinese aftermarket?
Did it start doing this after installing the new carb or has the new carb been working for awhile and now isn't working properly?

​​​​​​What does the plug look like?

 

The carb is aftermarket , when I bought the bike it was missing one. It has always done this with the carb. When the plug was pulled it was black. I was playing with the air to fuel screw and I found that if a rag was covering about 75% of the intake snorkel (https://www.arcticcatpartshouse.com/oemparts/p/arctic_cat/0470-383/snorkel-air-cleaner) then it would rev up, in neutral.

 

Your description is a little unclear to me so hope I understand what you are saying.

Your description sounds like a dirty carb. Even though it's new, I'd pull it, clean it, replace the jets, and try it. Those Chinese carbs often work fine....And sometimes don't work at all. Sounds like your main jet is either stopped up or is out of spec. A carb kit is usually pretty cheap so I'd clean it and put new jets in just to rule that out.

Also, the idle mixture adjustment is on the front of the carb. Funny thing about the pics on Amazon...the carb is upside down in the pics. Probably just for ease of photography. The idle mixture adjustment is in front of the float bowl on the bottom. There might be a plug over it (although the pics on Amazon don't show a plug).

 

 

They should not fall out. Something is wrong big time there. There is a oring, then a washer, then a spring, then the special screw. Any old screw won't work. You did have an actual idle mixture screw right? A carb kit will have the various jets and a new mixture screw along with gaskets and orings.

Also, there should be a rubber boot which connects the carb to the engine. Over time, they get brittle and crack. They then let air in and screw up the mixture.

https://www.arcticcatpartshouse.com/oemparts/p/arctic_cat/0470-412/tube-intake

 

 

I think you found most, if not all, of your problems. If the carb threads are destroyed that suggests to me that maybe it was cross threaded at the factory.

I always prefer the OE carbs if possible because the Chinese carbs can work just fine and sometimes they don't work at all. Chinese quality control just isn't there. The problem for you is, a new OE carb is close to $500 and I doubt you want to spend that much. You might get the actual numbers and brand for the OE carb and try searching eBay for a used one. A number of engines used that same carb so it's possible you might find an OE one used. Some OE carbs aren't much more than Chinese aftermarket but some are much more expensive.

While I'm not a big fan of Chinese carbs, if I had an older ATV that needed a carb and I didn't want to pour much money into it, I'd try another Chinese carb. You might check to see if Caltric makes one. They are one of the better Chinese aftermarket brands in my opinion.

Also while you are ordering parts, get a new carb boot. Given the age I almost guarantee yours is likely cracked and leaking. You might also want to replace the oring seal on the mounting pipe as a precaution too although that one doesn't leak too often.

https://www.arcticcatpartshouse.com/oemparts/p/arctic_cat/3423-332/o-ring

Let us know if you get it working!

 

Thanks for the advice. I will get a new carb and boot when the check comes. With the price of a new OEM carb, I could buy an EFI conversion kit.

 

In my opinion a good used carb and a quality rebuild kit would be far better than a chinese carb that is new. There are used part suppliers or junkyards out there, just hard to find.