i have 1995 yamaha 350 big bear and having problems when the bike first starts up, the bike idles real high even without the choke all the way in, the bike also starts to throw black smoke out the muffler, i had the carb off the bike this past weekend, and tried to clean it up, everything seemed to be working, not saying their is still could be something clogged or something needs to be adjusted, their is a new spark plug in the bike, seems like sometimes when the bike is warm she works better, is their an adjustment that needs to be adjusted or do the neddle valve need to be replaced i wonder, could somebody give me some direction on what i should try with the bike next

 

I also have the same model , idles very rough, black smoke from exhaust , runs ok in higher revs , I have cleaned carb , no difference

Perhaps some can help us both
Fogman

 

Mine does the same thing now & then. On mine, there is some sort of small tubing or hose that dumps out between the front tires just under the handlebars & fender. I guess it is some sort of vent or suction line from somewhere (never traced it), anyway, it clogs up with dirt & mud & causes the problems you describe...break up the dried dirt in the end of it & it starts running like a champ!

 

I have checked that small tube and it is clear , bike still runs rich on idle , choke completly off

 

I have a 2008 big bear, same problems. just bought it in july of 09 brand new, snorkeled it, still ran great, so I know it's not a mixture issue. it won't start without giving it gas, it idles like the timing is off. pop..pop..pop pop. ..... pop...pop.pop.pop....pop (that's how the exhaust sounds btw) and the exhaust has a very faint dark smoke. checked the plug and it was black. so that means it has been running rich, HOWEVER when I take the airbox lid off and take the filter out (which should make it run much leaner) it still idles the same and the faint dark smoke still comes out of the exhaust. so it's not the mixture. the carb either has a problem that's causing it to run rich or the timing is off somehow. one thing that bothers me is that the choke only seems to work about half the time. maybe the choke is getting stuck and causing it to run rich? I need some help too. I have an extended warranty, it would be nice if I could take it somewhere and the shop would bill the warranty company for something. I'm in the service business and that's what we do.

oh, it runs great when riding. as long as your on the throttle there is not problem. no lack of power, no sputtering, nothing. I haven't taken the carb apart, just ran some carb and choke cleaner through it and drained it a couple of times. I use high octane fuel too.