Mikuni TM 36-68 Pumper Carb
Text Box: I decided to install a pumper carburetor replacing the Keihn.
It works quite well giving instant response to throttle inputs.
Itís also very easy to change jetting.
Text Box: In order to fit the Mikuni TM 36-68 pumper carburetor to the KLX250 a few modifications are required
In photo above itís necessary to cut off the top section of the throttle actuator and the top of the push cable bracket to clear the bottom of the fuel tank.
In doing this you will no longer have a functional push cable. Not to worry as the Mikuni has a strong return spring and everything functions quite well.
The photo below shows a carburetor with the necessary materials removed
Text Box: Below are a couple more photos showing the removed material with the throttle pull cable installed.  The throttle actuator can easily be removed to facilitate cutting off the required material
Text Box: Throttle control with pull cable only. Push cable hole is plugged with RTV to keep dirt out.

The original pull cable can be used if the cable is re-routed however itís still very tight.
A good fix is to purchase a longer custom pull cable from Motion Pro. Be sure to tell them you want the pull cable only.
Below is a link to a diagram with the dimensions of the new pull cable.
Text Box: There is also a tight fit between the Mikuni idle speed adjuster and the regulator rectifier on the KLX250.
To make it easier to adjust the idle and ensure thereís no contact between the adjuster and RR cut back two fins on the RR as shown in the photo above
Text Box: I live in mountains of North Carolina, near Asheville at 2,300 ft home altitude.
I typically ride in altitudes from 1,000 ft to 3,500 ft and the following is the jetting that works for me.
Main Jet: 127.5
Pilot Jet: 17.5
Pilot Air Jet: 0.9
Needle Jet: P-4
Needle: 9EBY1-50
Needle Clip: 3rd slot from top (middle position)
Fuel/Air Screw: 2 turns out
A/P Pump Timing: Starts at 1/8 throttle and stops at 3/4 throttle
A/P Squirter: Pointed directly at the needle (fuel should splash off of the needle)

On a trip to Silverton Colorado I made the following changes that worked well.
These changes were made without removing or rotating the carburetor.
125 main jet
Moved the needle from third notch from top to second notch from the top