i have a 400ex that idles odd. It will run fun , but when idling it will all of a sudden drop down to a real low idle and then stall. it seems like a leak some where, but i made sure my air box boot and the intake boot were tight. Any suggestions.
thanks
nick

 

You can check for air leaks with carb spray(make sure you do it when the motor is cold). Start the bike and spray around intake hoses etc. until the rpm makes a change. Is the choke sticking? Have you done anything lately.

 

The only thing i did was go through the carb, but thats only beacause of the problem, i did read something about a cam bearing causing the same problem. IT does make a weird noise when it dies down in the cam area, then an odd clang and dies. it doesnt make the clang if its idling fine and i shut it down. If i ride it you cant even notice it. but soemthing is wrong. And im sure its not a air leak. really seems like it could be a cam bearing, but not sure. It is ticking and i re adjusted the valves and it still ticks. any thoughts

 

adjust ur idle alittle higher

 

if it was motor related(cams, chains etc) the noise should be consistent. Double check your carb settings. How many screws out are you on your a/f screw?

 

i am 2 1/2 out on air, the quad runs good has great responce. just this metal on metal clang ion the cam area is odd when the bike stalls. if it was a carb prob i dont think it would run good, then all of a sudden start idling bad and stall. Adjusting the idle might keep it from stalling but then it will be to high for the time it idles normal.

 

Adjust your idle speed up a bit. That clang is the cam chain smacking around inside your motor. If your motor is idling too low, and it is cold, it will tend to "hiccup" which will cause it to die, and for the cam chain to bang around when your motor jerks to a stop. I used to get a clanking or ticking sound when my bike was cold (only when it was cold and idling rough). I bumped up the idle speed, and the problem dissappeared. Give it a try, what have you got to lose??

 

i tried turning up the idle no good. the quad was running fine one minute, then i went inside started it up about a hour later and it wouldnt idle. when trying to ride it it just jerks around. The thing thats got me is it starts to make a weird noise in the cam area and when this happens is when it starts idling rough and dies. HAs this happened to anyone else?

 

Close association of the noise and rough idling makes me wanna say the automatic decompressor is sticking. Unfortunately, it's unlikely you will be able to see this by inspecting the cam. You could replace it, and the spring and pin in the head. Or, press the decomp off the cam and leave it, the spring, and the pin out. Reinstall cam and see if your problem goes away.

 

well dzzy, it does seem like something is sticking. After i wrote my last respence yesterday i went out and started it again, and it ran perfect, but iu know it will at no warnig start up again. what exactly is the automatic decompressor? not familiar with it? And if that i swhat it is do you think ridin the quad will make it go away? it has been sitting awile, i have only been starting it in my back yard, and no room to ride, so it really hasnt been riding in about a month.