[Ben]

Hi everyone, I want to do the airbox mods and uncork the exhaust as per many posts, I have ordered the JD Jetting kit, but will take a couple of weeks to be shipped here, does anyone have any guidelines on what stock jet sizes to use until my kit arrives?

I ride at approx 6000ft bout 70F and occasionaly ride at sea level.

Awesome site, lots of usefull info.

Thanks
Ben

[lance_m]

Hi Ben, I'm in the same boat as you almost.

Just bought an '08 250x, and I run it mainly around sea level and from 40 - 70F.

I'm doing the airbox cutout, air filter screen, and drilling the exhaust. Then rejetting with a JD kit.

The instructions say red needle, 5th clip, and 160 - 165 main jet. Pilot doesn't need changing on '07s and '08s apparently.

Let me know how you get on, and I'll keep you posted.

Lance

[redrooster65]

I would go with the 155 main 42 pilot and red on the 4th.

With the 150 it is perfect at my normal riding area but I am afraid it would be too lean the few times I ride at lower elevations, It ran good at both with the 155

Runs crisp with o bog.

Year: 2004
Elevation: 4,000 - 9,000
Temperature Range: 50 - 100
Smog (AIS): No
Airbox Modified Top: Yes
Airbox Modified Sides: No
Backfire Screen: Yes
Air Filter: Stock
Pilot Jet: 42
Main Jet: 155 now 150
Needle: Red
Needle Clip Position: 4th
Fuel Screw Type: CRF's Only
Fuel Screw Setting: 1 3/4 now 1 1/2
AP Modified: No
Leak Jet: 55
AP Cover: No
Exhaust Type: Stock
Exhaust Modified: Drilled
Pink Wire Modified: Yes

[NCFRC]

If you look at other 250X posts on here, you'll find some very similar suggestions.