Why 2017–2026 Models Are Different

On older 2011–2016 EXC and FE models, changing the idle speed screw did not significantly change TPS voltage because those throttle bodies used an air bypass plunger design.

On 2017–2026 KTM EXC and Husqvarna FE models, the idle speed screw works differently. Adjusting the idle screw rotates the throttle butterfly itself, which means TPS voltage changes when idle speed is changed. That is why the TPS must be set with the throttle butterfly fully closed and with the yellow enrichment knob fully disengaged.

The factory service manual refers to the TPS voltage as THAD, and the correct baseline specification is 0.400V ± .004V.

Step 1: Fully Disengage the Yellow Cold Start Knob

Start by making sure the yellow cold start / enrichment knob underneath the throttle body is not affecting throttle opening.

1. Pull the YELLOW cold start knob down to disengage it.
2. Back it out counterclockwise all the way until it stops.
3. This ensures the cold start circuit is not opening the throttle body and throwing off your TPS setting.

This step is critical. If the yellow knob is partially engaged, your TPS reading and idle settings will be inaccurate.

Step 2: Set Base Idle Speed with the Red Knob

Once the yellow knob is fully disengaged, you can set your normal idle speed using the RED idle adjuster knob on top of the throttle body.

1. Start the bike and let it warm up completely.
2. If necessary, use a small amount of throttle input to keep the engine running while it comes up to temperature.
3. Adjust the idle speed using the RED knob.
4. Set idle speed to the factory specification with the engine fully warm.

Always set idle on a warm engine. Trying to set final idle on a cold engine can lead to poor running and inconsistent results.

Step 3: Reset the Yellow Cold Start Knob

After your base idle is set, you can dial in the yellow cold start knob so the bike starts properly when cold.

1. With the bike running, push the YELLOW cold start knob in to engage it.
2. Turn the knob clockwise until the engine idle speed increases.
3. From there, turn it 3 more clicks clockwise to establish your cold start idle speed.
4. Pull the yellow knob back down to disengage it. Idle speed should drop back to normal.

This procedure gives you a useful cold start setting without leaving the enrichment circuit too far open.

Step 4: Reset the TPS to Factory Spec (.400V THAD)

If you have moved the TPS on the throttle body, it needs to be returned to the factory setting. This is where many people get tripped up on 2017–2026 models.

1. Make sure the YELLOW enrichment knob is fully disengaged and not opening the throttle.
2. Back the RED idle speed screw out until the throttle butterfly is completely closed.
3. Measure TPS voltage and adjust it to 0.400V THAD.
4. Once TPS is correctly set, turn the idle speed screw back in and re-adjust idle to spec.

This is the part the service manual does not explain clearly enough. The TPS must be set with the butterfly fully closed. If you leave the idle screw in, the butterfly stays open and the voltage reading will be wrong.

After the TPS has been properly set and the idle screw is turned back in, the TPS voltage will typically rise to around .54–.55V at idle. That is normal on these bikes when idle speed is set correctly.

Important Notes

• The yellow knob must not be opening the throttle during TPS setup.
• The idle screw must be backed out so the throttle blade is fully closed before setting TPS baseline voltage.
• Do not compare this procedure directly to older KTM / Husqvarna throttle bodies from 2011–2016. They work differently.
• If the bike has had previous throttle body or TPS adjustments, returning everything to this baseline is often the fastest way to fix idle and off-idle issues.

Common Symptoms of Incorrect TPS or Idle Setup

• Hard starting
• Bike will not idle without throttle input
• Erratic or hanging idle
• Off-idle hesitation
• Inconsistent cold start behavior
• Poor running after throttle body or TPS adjustment