Has any one else had any problem with thier 400EX smoking? Mine seams to blow white smoke until it is warmed up then only when I am riding hard such as when I am climbing up a hill. It is completely stock except for a Uni- air filter and a #40 pilot jet.

 

did you change the main jet or anything that would involve the fuel settings?

 

I did change the main jet from a 148 to 150.

 

pulll off the intake boot on your carb and feel around and see if you feel any sand. Also did you check your oil? not too full not too low. Also you might be not letting the oil on your air filter to dry enough. when you pull off the intake see if there is red inside from the air filter oil or check the over flow that is hooked up to the side of the intake hose. It could be you are burning off oil from the filter and you only notice itwhen it starts up because it has sat at the bottom of your airfilter and then it pulls it through . then when you are at full throttle you are pulling more air through the filter.....

 

I usually let my air filter set for 24 hrs. before reinstalling it, but I have been using PJ1 filter oil and it is pretty thick, I'll pull the boot off tonight when I get home and check for dirt or oil. thanks

 

it doesn't really matter how long you let it dry... It is oil.. As you ride it the oil losses it's viscosity and starts to brake away from the filter.. On my k&n i can let it try for 2 days and if i go out for a few hour ride, when i come back there will be red oil on the botom of my airbox... This is normal... however some will get through the air filter and get into the motor this is also ok since it is oil it will just burn off... Just *** long as it ain't flowing through there like you were spraying it in.....

 

We had a smoking 400EX, the valve seals were shot from the sand that went through them.