Just purchased a 2002 660 Grizzly with 3995 km on it and around the 550 hr mark. The guy I bought it from just had some carb work done. I had it for a short ride and was kind of boggy but took it for just not being warmed up. I find though even when it is warmed right up( the rad fan comes on) at low rpm (no tach) it will stumble to the point of stalling under load unless you engage the choke part way. I don't have a service manual (on the way) so I was wondering if any one has had the same problem and how did you fix it? The carb work was a new float needle.

 

Did you try raising the idle by turning the adjustment **** #40 to see if that helps.

 

I turned up the idle which didn't help. The machine starts excellently and sits there and idles no problem. If you don't put any load on I can slowly bring the RPMs to over half throttle and higher and no hesitation. If I get it out in the field and get past the hesitation it goes really good. When I slow down and try to drive it at a walking speed it backfires, bogs, sounds like it is choking but if put the choke on the revs pick up and lots of power. get rolling and push the choke off and away you go. If I nail the throttle hard there is a hesitation but you go. Just at a walking speed it wants to die. Any more ideas? I drained the fuel and carb, no dirt or water and put in a new plug. Would the pilot air jet cause this problem?

 

Sounds like the carb needs a cleaning or set up or both.
Yes the pilot is a trick. When that is fooled with your suppose to count and write down the turns to bottom it out before removing it, that way you just bottom it out once again and reverse the turn count when reinstalling it so its exactly back where it was.

I know this is a round slide not a CV carb but it gives you the idea. Disassembly and Cleaning of a Mikuni Round slide Carburetor

 

That was what I was leaning toward, Just didn't feel like pulling the carb apart. I am a registered Echo, Kohler, Briggs MST technition but was hoping it would be some thing simple. Carburators are the bane of small engine mechanics. Besides it's a real pain in the butt to get to the carb.

 

You will love the ATV when you get the carb tuned.
My friend has a 2003 660 Grizzly and a new 700 Grizzly efi and the look and drive the same to us.

 

Well, I pulled the carb apart, gave it a shot of carb cleaner 'cause I didn't have access to a ultra sonic, blew it out and started to put together when I found a tiny tear in the diaphragm. I stuck a piece of electrical tape on it till a new one is in my hand. Works a lot better but I have a new question which I will start a new subject. Thanks for all the advice given.