Dirt in float bowl, where's it coming from?

[Gary B.]

My YZ 400 has some amount of fine sand or dirt in the main jet cap after nearly every ride. I checked and the tank is clean. I don't know how else it could get in there. Any ideas?

 

[mobrown]

Filter

You probably need to put an in-line filter between the tank and the carb. Dirt small enough to get in the carb you probably won't even see. What you see in your jets is an accumulation of very fine particles.

Also, make sure your air filter is cleaned and oiled before each ride and that there is a good seal between the filter and the housing.

 

[Ol'89r]

My YZ 400 has some amount of fine sand or dirt in the main jet cap after nearly every ride. I checked and the tank is clean. I don't know how else it could get in there. Any ideas?

Gary.

Considering that your air cleaner is clean, oiled and properly installed, check the little rubber boot on the accelerator pump rod. These can become dislodged and dirt can get down through the opening.

Also, check the rubber tube that goes from the hot start button assembly to the air box. If that tube is not connected it will suck dirt through the hot start system.

Just my $ .02