I will bet in 25000 kms the "Puke Tube" is full! Find it, drain it and put the plug back in it! The nasty stuff in the tube won't burn. Located at the front of the CVT cover, black plug, finger spring retainer. Squeeze the spring and slide it up the tube, pull the plug carefully. Stuff stinks like gasoline and other things unrelated to fresh air. Draining may not fix your speed problem but couldn't hoyt!