The KTM Group 125, 250 and 300 SX models all come with an electronic power valve which is operated via an electric motor controlled by the ECU. This power valve is programmed to open at a certain RPM over a preset duration. When the cylinder has been removed to do any work such as replace the piston and rings then this power valve needs to be reset. Here’s how to reset a KTM TBI Power Valve

#1

Firstly you will need the wake-up dongle that fits your brand of motorcycle. While the KTM, GASGAS and Husqvarna all require the same process to reset the power valve, they all require their own brand-specific dongle that can be purchased through your dealership. If you bought your motorcycle new from a dealership then this wake-up dongle should have come in your spares kit with the bike.

#2

Remove your seat and locate the communication plug under the seat. On some models this plug is floating around and others it is fixed to the airbox. Once you locate it you will need to remove the plastic protective cover by pressing in the locking tab and pulling the cover off.

#3

You will then need to mark the halfway position on your throttle housing. The easiest way to do this is mark the closed position, then the fully open position, and then directly mark the centre position using either a permanent marker or paint pen.

#4

Start with the wake-up dongle slightly plugged in but not pushed all the way in that the ignition wakes up. Having the plug partially inserted makes it easier for you to connect it all the way using one hand and then frees up your other hand to work the throttle.

#5

Hold the throttle at the halfway position and then squeeze the wake-up dongle so it connects the entire way and the ignition wakes up and the lights illuminate on the map switch.

#6

Hold the throttle in the halfway position for 10 seconds and then let the throttle close completely. At this stage you will hear a bunch of noises as the power valve cycles through its end ranges of motion and sets its end parameters in the ECU. Once it stops you can disconnect the wake-up dongle and the map switch light will go out after a few seconds.

#7

Once you have finished this process you start the bike and make sure it revs correctly and runs as it should. Once you are happy that the bike is running correctly you can fit the communication plug back into place and then refit the seat.

Dos

  • Make sure the bike’s battery is fully charged before completing this procedure.
  • Use only the wake-up dongle that fits your make and model.
  • Reset after each time you have had the cylinder removed from the engine.

Don’ts

  • Use paper clips or loose wires in place of the correct wake-up dongle.
  • Try to perform this procedure with a low battery.
  • Skip this procedure or the motorcycle will likely bog or not rev correctly.

TOOLS

Wake Up Dongle

WARNING

If you don’t perform this procedure correctly or not at all after having the cylinder removed it will likely result in the motorcycle bogging or not revving correctly.

EXTRA TIPS

Two-stroke motorcycles have long been known to load up with fuel when idling for too long and the answer has always been to rev them hard to blow all the excess fuel out of the engine. Unfortunately this is not the case with a TBI model two stroke.

If you have a TBI model two stroke that has loaded up with fuel and it is spluttering and it won’t clear out by revving it at constant full throttle then stop and rev it on and off to about halfway through the rev range. Holding it at constant wide open throttle will continue to pump fuel into the engine making your problem worse, whereas continuing to rev the engine up and down to half rpm will clear the engine out without loading the engine up with even more fuel.