Well, I cleaned the jets (all three of them) It was easier than I thought. It runs just a little better but still rough slow idle (somewhat like a Hog). I notice black smoke from the muffler. Its Burning very rich. The spark plug that I cleaned sunday was really carbon fouled. I'm going to put the atv back together and take it to a local motorcycle shop then possible to the arctic cat dealer if the local guy can't help.
Thanks
Roger

 

Youre almost done, dont give up now.
You just need to fine tune the mixture screw, and adjust the idle speed.
Lightly screw in the mixture screw, until its seated.Do this lightly, too much force and the seat will deform. From there, back out two turns. It should be able to start and idle here.
Turn the idle up, with the idle adjust screw, and have it slightly faster than normal.
Ride it until its warm then , slowly screw the mixture screw in until it drops rpm, then slowly go out, until you find the spot with the highest rpm. Then turn the idle adjust screw, until the idle speed is correct, and you should be done.
Thats all there is to it, dont take it in for this.

 

Well, that was $45 down the drain. Had the local shop adjust the carb, idle and blow out the muffler (been over a year and every close to 500 miles without ever being done.) Isn't as rich burning but still won't idle without the choke and alittle gas. Talking to my father, telling him it almost like a vacuum leak on a older car. No hissing but won't run at idle but give it gas and it almost smooths out. Mine idles good and sounds good at half choke.
Got the atv on the trailer and strap down for the 2 hr ride (one way) to the cat dealer. I really hope he can fix it without costing too much money.
Thinking out loud: could the pilot jet go bad but still looks ok?
Roger

 

You might also want the AC dealer to check the float level adjustment. I have heard of people knocking the float out of adjustment by running the carborator dry after putting the bike on a trailer and then the float just sits there and bounces all over with no fuel to float it. Knocking it out of adjustment.

Then again you may just need a different pilot jet. Good luck and I hope your dealer can get it back on the road again.

Service Manual says float Arm Height is 17mm (0.7 in)

Main jet 150
Slow jet 38
Needle jet 4.0/3.4
Jet Needle N8TV
Starter Jet 60

Also just to check to make sure its not sucking air around the intake or anything. Start it and spray WD40 or something similar around the carb and intake. It the RPM's change then you have an air leak.

 

If he had an air leak wouldn't it be running to lean right now, not the symptoms he is talking about??? I know on my dirt bike if there is an air leak it runs like a raped ape, because it gets to much air. Just my 2 cents.

 

Yes, you are right he probably would. I just always like to check everything to rule things out. Was thinking that if he hit something to crack the exhaust pipe he might have cracked something else.

 

Had to work overtime today but just started on checking the float of the carb and got my first question...
how do I measure the distance. I know its 17mm (0.7in) but how to place the carb on the table and from what to what do I measure?
Roger

 

the small crack in the exhause pipe wasn't a real crack, it was where the pipe slips into the muffler.

 

I had the same problem on my Mikuni carb. The reason was that the main jet needle got disconnected from it's clip and fell into it's hole. Don't know if this will help, but check it out.

 

I have always measured the float height by taking the bowl or float chamber off the carborator. Turning the carb upside down. Measure the distance between the flat part on the float where the float valve attaches to the float and the carborator body.

I have not had to do this on either of my AC's but have had to do it on an old 250 suzuki I owned. I am assuming that since the 400 is a suzuki engine its done this same way.