'99 KX250 jetting questions

[freds40]

Tried the jetting forum but not getting anything there.

I recently picked up this bike. It's got an FMF Gnarly pipe, Turbine Core 2 Silencer (just repacked it), new Boyeson stock reeds, Twin air filter, and I got a JD Jet kit. I've got the #45 Pilot, the 168 main, and the Blue needle on the 3 notch.

Riding 2 track (idling and wound out) at about 5500' I'm getting a bog off idle and a slight drip of splooge coming off the silencer at the end of a 45 minute ride. I've got the air screw 3 turns out and understand not to go further. The idle is still a bit high at 3 turns out.

The splooge I'm not too concerned about as I figure the low speed stuff is what's causing that. From what I've found, it sounds like I need to look at the Pilot jet to cure the off idle bog but wanted to verify that before I start just guessing.

Any help is appreciated.

[cxcmoto]

My first adjustment would be to put in a 42 pilot and air screw at 1.5 turns out. The fact that the air screw is out that far tells me the pilot circuit is too rich. You might need to lean out the main also. Need to adjust for the elevation.

Here is what FMF says ----

We developed these specs with a 32:1 fuel to oil mixing ratio of a 50/50 mix of race fuel and super unleaded, 0 - 1500 ft altitude at 70 degrees outside temperature.

Please note: There are way too many variables in jetting to give you a recommendation that works perfect. Use these specs for a reference to help aid you with your specific bike.

Make Your Selections

Jetting Results

* Main Jet

* 155

* Pilot Jet

* 45

* Needle

* STOCK

* Needle Position

* 3RD

* Power Jet

* STOCK

* Air Screw

* 1.5

* Fuel Screw

* N/A

JD can also probably tell you what to do with it based on your riding style and elevation.

[freds40]

I had seen that but didn't know how those numbers compared to JDs as I've heard they use a needle with a slightly different shape so it changes some of the jet sizes. Yesterday I ordered up a 42 and a 40 hoping that would allow me to back the air screw off.