DISCLAIMER: YOU DO THIS AT YOUR OWN RISK AND MAY VOID THE MANUFACTURERS WARRANTY.

Step 1. Before turning the ignition on press and hold Select and Reset buttons, turn the ignition on and keep holding both buttons until you see the Diag screen appear.

Step 2. Press Select once to toggle to the CO MODE

Step 3. Press both Select and Reset together. Hold for about 3 seconds to enter co mode. The number displayed is the cylinder selected (genereric computer for all Yamahas) You need to select 1, Press select to scroll up and Reset to scroll down.

Step 4. Press both Select and Reset simultaneousley for a few seconds to see the setting for the selected cylinder. This number will be different on every bike and has no relationship to the mixture its just a number it can range from -128 to +128. Write down the number and keep it in a safe place in case you need to return to your original settings.

Step 5. Pressing select will increase the value (richen the mixture), pressing Reset will decrease it.

I initially increased my setting 5 digits from 10 to 15. This smoothed the bike out but still had a little surging. After reading what Alan and others have said it should be safe to increase your original setting by up to 10 digits. I will now adjust mine up another 3 to 18.

Step 6 To exit CO mode, turn off ignition.

Noticed benefits. The bike is now very smooth to ride and on my 1st adjustment took out almost all the surging/jerkiness. This has made the bike much easier to ride through corners where i can now get on the gas earlier in the corner increasing the mid corner speed.


More info can be found on the forum: fueling fix.

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.

Seems like you sorted your bike out well, it cost me a fair bit of dosh to get mine sorted ! did you have any problems with the bike cutting out,another of our members has this problem i thought it could be the throttle sensor?

My bike cut out from the very day I bought it. I took it back to the agents a few times, they had no clue what the problem was, that was a year ago. It was very intermittent.

I then started to do a little research on the fuel injection system. I found away to richen the CO through the dash & moved the throttle sensor up in angle & never looked back. No more cutting out

The bike still ran very lean. A few weeks latter I then played with the Temp sensors. Add two variable resistors & that richen it up nicely.

I have also made 2 spacers for the front fork springs, as I have found the front end starting to sag. Spacer size 37mm outter, 25mm thick, with a 20mm hole in the center. The front end feels nice & stiff & has not topped out with the extra spring tension.

Hi kev!

Nice one there. Looks like you have managed to outrun the system with that trick.
It looked almost like one trick we used to try on the Golf GTI 16v. There you have a full throttle switch, wich we runned over a relay with a sertain resistor connected to it so it was fooled to belive that the engine was cold and opened the coldstartvalve. But only when you pushed the pedal to the metal

Please let us know how you did it and wich ohm you used for the air and coolant temp senders so that others could try it

Nice mod

Hi Stoppstadd

I left the motorcycle trade as a mechanic after 12 years & now have work for Volkswagen for the past 14 years. As a workshop foreman. I have been playing with fuel injection systems for a few years now. So the Xt was pretty easy to sort out.

I used 2x. Adjustable resistors from 0 Oms to 1k Oms, rated voltage 50VDC & 0.8 watts. You can get them from you local electronics shop.

I cut the Coolant temp wire green/red in half, just below the fuel tank. Ran two wires from the variable resistor to each end of the cut wires & joined them. IE, the resistor between the cut wires. I did the same for the Air temp sender. IE, the resistor between the cut wires.

I then went in to the dash into zone 5 & 6, then adjusted the Air & Coolant temp sender deg C & found after may hours playing. The best variable for my bike, being 5 degs C below the actual reading. I can turn the resistors to 0 Oms & the bike is back to STD for work, good fuel consumption. Then can adjust the resistors up, in turn lowers the temp deg C, for the weekend mountain racing. I have marked the resistors 5 & 10 degs settings, for quick adjustment. I had already adjusted the CO up some time before I carried out this mod.

Great!

Another easy way to fool the injection system.

I dont need it becauso of the PC wich i quick adjustable manually if you want to richen the mixture. But maybe for someone who wants to save a buck its worth it.

I have not worked with VW but im a audi/ VW freak and i have owned about 20 golf cars and several audis over the years but my favourite is still the audi UR quattro -81 a silvercoloured one that i had 10 years back. Had to let it goe because of military duty I still miss it...

Good work/ information ther kev!

Kev, that sounds very interesting and I am sure our members might find it extremely useful on their bike, however is there any chance you could take some pics of the step-by-step operation so we can publish it here and call it the KEV-MOD?

See what you can do. Thanks a lot for the tip

Fueling fix photos, of Air & Coolant sensor wiring. Red wiring for Coolant temp adjustment, yellow wiring Air temp adjustment.
Also warm the bike to operating temp before setting the variable resistors.

Hope it helps someone.

Kev

Excellent work Kev, later I will make this a dedicated thread called the Kev Fuelling Mod.