My ac650 barely starts when it is cold, dealer has worked on the choke twice. His mechanic flipped out when I brought it back the third time and said he could not fix it. When the choke is "off" I think it is still closed slightly in the carb. Any help?

 

Same here, I have a 650 also (04) and I don't trust taking it anywhere because it is very, very, very hard to start!
I keep my garage at 40 degrees and it struggles to start even at that temp! I bought this thing for ice fishing and I'm afraid to take it out when the temps are 25 or below, not to mention it is flat out embarrasing.
It is an "Arctic Cat" you would think it would start easy.
So what are you going to do next? It's been a while since you posted this, have you found a solution?

 

Can't help you with your 650, but my '05 400 with auto choke has started everytime in as cold as 16 degree weather. No fuss and no problem. I prefer manual chokes but this system has worked flawlessly. Is the '04 650 really a choke valve system or an enrichment system like the '05? I mean either sytem is pretty simple and any mechanic that cann't adjust one probably isn't much of a mechanic. Find a different dealer, or if you have any mechanical ability get a shop manual and do it yourself.

 

Just a little note, last night we had my bud's 650 apart, looking for a fuel leak. We found that the choke plunger on the rear carb was stuck in its' bore, wouldn't move at all, and had the carb stuck with the choke partially on. This allowed it to idle off of that carb, and a little bit of adjustment on the idle adjustment screw would compensate for the front carb. . Once we took the choke plungers out, we could see that it was flooding the float bowl, then running down the choke cable and dripping out at the junction. Also, we took the throttle cable housing off, and with the idle adjustment screw turned all the way in (for fast idle) it was barely moving the throttle plates. We had to bend the tab to make it contact the adjustment screw at half way in, so we had some kind of idle adjustment.
After that, we got it started and noticed that the carb throttles were opening at different rates. The rear carb was opening first, followed by the front carb. You could see the rear diaphram moving while the front was still. They SHOULD move the same amount, simultaneously. We synchronized the throttle plates so that they opened together using the adjustment screw in between the carbs, and now had adjustment for idle speed as well. I don't think these carbs were set up from the factory, or even looked at prior to delivery, they just set the idle adjustment screw to get a half decent idle and left it at that. Really, you guys should check your carb set-up, I'm willing to bet you guys have some, if not all, symptoms. That rear cylinder was burning rich from day one, with the choke stuck on. He did notice a slight bog too, which is gone now, and the throttle response is a lot better.
The choke plungers might be sticking in their bore, causing the motor to run rich and carbon itself up. Your carbs really need to be looked at, and set up if necassary. Since we've fixed them, he's hardly had to use the choke at all, it fires right up as soon as you hit the starter. The choke is also easier to operate, so if you have a stiff choke lever, this could be your problem.

 

http://www.brownsleisureworld.com/Pa...CARBURETOR.htm

Try this link for a breakdown of the Keihin carb. This one is off the 500, but it's the same principle.

 

I hate to hear you guys are having problems. There has to be a reason. My 04 500 starts like a dream down to about -5 f . It may start below that but it has not got that cold here yet this winter. Check it and see what you can find as it should start better than that.

 

Well I took a look at my air cleaner and plugs today...I need to pay more attention to that air cleaner, talk about filthy!!! The plugs ( I bought new ones) were black as could be I am assuming no air = rich. I will let you know how it all works out. I also sprayed the carbs with cleaner

 

The 650 runs 2 of 500 carbs. So it's not the same principle it is the same, exactly.

 

Thought the 650 used 32mm carbs, and the 500 used 34's or 36's, but I've been wrong before. In any case, you guys with the 650's really need to check them out closely. The one we adjusted is running like a top now, better than new.

 

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I have had a 2001 Bear Cat 250 4x2 and now a 2005 400 4x4 and both were cold weather dogs when it came time to start at near freezing temps. I live in the NE PA mountains. My dealer (Rusty Palmers in Honesdale PA) told me in 2001 that all Arctic Cats hate cold weather start ups but when warm run great all day no matter how cold it gets. I have found this to be true. I went 2 minutes this weekend 29 degrees trying to start the 400 (self choke system)in the shed before life kicked in.....I have learned to live with it.