Apex Digital Pro MXR 90 - Engine Tuning and Components; Carburetor Tuning and Cleaning

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1mm Variator Shim
Put 1mm shim inside Variator to increase 1st gear ratio. This will reduce top speed but get off the corners quicker.
Run this mode on short quick tracks.
Put 1mm shim outside the Variator half’s to decrease 1st gear ratio and increase max speed by allowing for a
lower final gear ratio across the CVT. Use this mode on long desert style tracks to reduce belt load. This is also
good for dirt road riding with larger bikes to allow for more top speed.
Carburetor Tuning
Unit is supplied with 24mm PWK Carb with 118 main jet and a 45 low jet. This carb is also equipped with a High
Speed Power enrichment circuit which will supply more fuel at higher RPM’s. The Main Jet can be lowered after
engine break in. (first 2 tanks of fuel) if required. If the motor seems to load up off the pipe the main jet is too
large. With the power enrichment circuit the main jet will be uncharacteristically low in value due to the makeup
of fuel flow by the enrichment circuit. Adjust the Low Mixture Screw out 1 turn to start. Turning more out will
increase low end punch but load up off the pipe more at lower RPMs. Turning in will clean up off pipe cackle but
soften bottom end of motor.
Carburetor Cleaning
1. Make sure the fuel is shut off.
2. Remove the carburetor.
3. Drain the fuel in the carburetor.
4. Disassemble the carburetor.
5. Immerse all the metal parts in a carburetor cleaning solution.
6. After the parts are cleaned, dry them with compressed air.
7. Blow out the fuel passages with compressed air.
8. Assemble the carburetor.
9. Install the carburetor back on to the ATV.
Warning:
 Clean the carburetor in a well ventilated area and make sure there is no spark or open flame near the
work area. This includes any appliance with a pilot light. Do not use gasoline or low flash-point solvent
to clean the carburetor.
 Do not use compressed air on an assembled carburetor, the pressure may deform the float.
Reeds
Take the reed cage out and hold it up to the light and look in through the cage. If you see light between the reed
pedals and the frame, replace the reeds. If you do not see light the reeds should be OK.
Warning:
 The reeds must lay flat on the reed cage, if the reed tips aren’t lying flat, replace them immediately.