Making the throttle light as it should be

One of the things I didnt like on the Xtrainer is the hard throttle pull.
In normal riding condition its not so bad, but when negotiating super technical obstacles or when you need the last bit of traction, precise throttle control is required and the hard pull won't help.

Trying to understand the source of the problem, I tried first to re-route the throttle cable. Didn't help any, even when (for the sake of the test) I had it completely straight.

Taking routing out of the question I have been left with one option only - the TPS lever return spring!

Compering to the buttery smooth any EU 2S bike with Domino throttle, the Xtrainer (and starting in  2016, the 250/300 RR's as well) equipped with a different version of the Keihin PWK carburetor. This version have a TPS (Throttle Position Sensor) installed, together with a leading arm which is spring pre-loaded forcing the TPS arm against the slide to eliminate hanging.
The problem is that Keihin left the same PWK spring in place, and the hard pull caused by the added resistance of both springs together.

9$ later, I bought another PWK spring and trimmed about 1/3 of the length. Install it back in (trimmed side up) and VOILA! smooth and easy as it should be :)

Now I got it right!
I did a custom made throttle springs, softer than the original and throttle pull went to where it should be. Got some extra if some interested! :)