i just got a 2000 400ex- i live in alaska and the temp is usually around 20-30F and it is virtually impossible to get it to idle--- the mech at the honda place said they are set up for warm weather- my wife has a brand new 300ex and it idles fine-- any suggestions or answers???thanks!!!

 

Put a two size bigger pilot jet in the carb, I think stock is a 38 so go with a 42, and maybe close the air mixture screw on the bottom of the carb 1/2 turn.

 

norm is right, it makes a world of difference on cold starting. It also helped mine out a little on low end power and gave it a quicker throttle response.

 

a friend of mine has found that if you give 3pumps of the throttle that it starts right up