Just rebuilt the carb on an '02 KQ300 (Moose kit). The quad will not run without the choke, unless I work the throttle or increase the idle. If I increase the idle, it revs really high when the choke is on. I am certain that the carb is clean and clear. I have already checked eveything else, like valves, air filter, spark plug, etc. - all is good. I believe that it is carb related. I removed the air box lid and did not notice a difference. Any help of suggestions would be appreciated.

 

Is your choke the butterfly plate type, or the fuel enrichment type? (pull a rod on side of carb to open passage for more fuel for cold start). If it needs the choke or more throttle to run, maybe you set the float too low, and it is starving for fuel. Other than that, you could still have a speck of dirt somewhere, clogging the idle circuit,because if you turn the idle up far enough, you lift the slide enough to pull fuel from the main jet, but also causing a high idle speed. Just 2 thoughts on it, havent looked at a KQ 300 carb in a long time, so not sure what type it is.

 

Its a fuel enrichment type of choke and I second on the float or idle circuit

 

Thanks for the responses...It is a fuel enrichment type (plunger on the side of the carb). I will check the float level again, but I set it at 13MM (per the service manual) during the rebuild. It starts with the choke on. It will run with run at half choke, but it idles really low. As I approach no choke it dies. FYI...The reason I decided to re build the carb was because it was running really rich. I can't remember if it had this "won't run without the choke" issue previously.

 

sounds like pilot jet is plugged did you remove all jets and clean them thouroughly with carb cleaner and compressed air while you had it apart?

 

Yes, I replaced al of the jets with new ones (Moose rebuild kit). I verified that all jets were the same size as stock. I spray all of the passages out with carb cleaner and blew them out with compressed air.

 

I went thru the carb again. All passages are clear, the jets are the correct size, the float height is set at 13MM, choke is working properly, needle is set on the correct clip, etc. I checked the intake boots and they are not cracked.

Put it all back together...I adjusted the idle down to a reasonable level with the choke on. I then tweaked the idle further until I could get it to run with no choke. I also turned the pilot out another 1/2 turn (2-3/4 out now) in an effort to keep it running with no choke. It doesn't idle super high when I turn the choke on now.

Still not running right. It starts fine. It idles OK, but sometimes it sounds like it is surging. I pulled the plug and noticed that it is covered with carbon, so it is running really rich. This was what started the whole carb rebuild...I do not see any excess fuel coming out of the overflow, so I assume that the float is OK. It is about 30 degrees F here in Indiana, so I would have thought that running slightly rich would be OK, but this is too much.

Any ideas? I suppose I could lean out the pilot circuit, but I have to take the carb off to get to the pilot (major pain).

 

Per my 04 model Arctic Cat manual, it has the float set at 17 mm (yea, I know, its a Suzuki in AC plastic). My experience with it only idleing with the choke on has always been a plugged up slow/idle jet (my small Yama is bad about that). That jet is small around but long, and some of those holes in the upper part will be plugged up. I generally will have to cut a small piece of multistrand wire, remove one tiny wire to push thru those tiny holes. They are so small on the Yama that even with a bright light, it is hard to see any light thru them when they are clear of trash. Also, if it still idles rich after everything else is right, this would be the jet to make smaller.

 

I ended up setting the pilot at 3-1/4 turns out (major pain, because I have to remove the carb each time! I coulnd't even reach it with the Motion Pro pilot screw tool). The quad starts & idles good. While riding it, I notice that once in a while, when revving it up and then chopping the throttle, it will die. I raised the needle (lowered the clip one position - now 3rd from the top). This seemed to eliminate the low speed dieing problem. The plug is clean and it carbuerates well.