I have been playing with the fueling on my Xt660X to improve it's performance & rideability.

I have fitted variable adjustable resistors to the Air temp sender & Coolant temp sender. Adjusted them to lower temp readindgs, of 5 deg C for both. Increased CO from 9 to 28. Adjusted throttle angle sensor from 16 to 22. Removed the snorkel from the airbox & added 2X 50mm holes to the airbox. I still run STD pipes.

The bike rides very smooth now, with a little improvement throught the whole range & not much more in fuel. This might help other riders who can't afford a power comander or local Yamaha dealership that can't get your Xt to run smoother or stop it cutting out.