Pilot Jet Too Rich?

[markcr]

2003 CA XR400R, Snorkle removed, UNI filter, FMF Q2 w/ stock header, 160/60 jets (stock needle, 3rd position). Running at sea level.

Symptoms: Won't start or run at all with choke on full. Starts ok with no choke.

It idles but dies immediatly if I twist quickly on the throttle. I only get an increase in idle when I turn the fuel mixture screw in to completely seated. After about a 1/2 turn out, the idle starts dropping (which is what makes me think the pilot jet is too rich). Thinking about a 55 pilot.

Any thoughts?

Thanks!

[XR250rdr]

If the motor doesn't die with fuel screw in completely the pilot jet is too rich. Go down one size at a time.

[jayc250x]

I only get an increase in idle when I turn the fuel mixture screw in to completely seated. After about a 1/2 turn out, the idle starts dropping (which is what makes me think the pilot jet is too rich). Thinking about a 55 pilot.

Sounds reasonable to me. I'm running 58/158 in my '98 and it is perfect - explosive throttle response right off idle. I have the snorkel pulled and run a stock filter, but have 2/3 of the backfire screen removed - I cut the front screen out and removed the fluffy steel wool that is between the two layers of screen-door screen. Now, there remains only one layer of screen-door type screen (run a bead of JB weld around the outside of the screen to seal in the cut edges of the front screen if you do this. It eliminates the chance of a stray piece of missed screen wire getting pulled into the motor). I think cutting out the backfire screen does as much as pulling the snorkel.

JayC