Above o2 link is dead
 

Want to purchase the o2 mod. Could someone give a link to somewhere i can purchase it. Does it come with instructions.

Send Kev a PM or buy on eBay...

http://www.ebay.com.au/itm/Yamaha-XT...item1e77c5c493

Yes

I have a 6 X O2 controllers left as I have sold more than expected, with the OEM connectors on back order again so not sure when the next batch will be ready last time it was 2 months before I got the back order connectors.

Kev's mods

http://www.xt660.com/showthread.php?t=20592

So, let me see if I got this:

O2 eliminator required to fix closed loop so the jump in AF ratio between closed and open loop is not so big.
On that note closed/open loop refers to idle throttle/open throttle.. ?

Moving on - Kev's mod fixes the open loop AF ratio so that you can turn the knob to experiment and find where you feel the bike running better (as in stronger or smoother?)

And may I ask - where have you all fitted it? I've got the ABS version there is *no space* under the seat to speak of. Will I need to dismount half the bike to fit it?

Yes. It fixes the AF ratio to 13.6:1 instead of 14.7:1

Sort of, but it's a bit more complex than that.

Closed loop is where the O2 sensor is feeding information back to the ECU about air/fuel ratio and fixing it to 14.7:1 - this happens at idle, small throttle openings and constant throttle when cruising below 3500(ish)rpm. It will be fixed at 14.7:1 regardless of what any fuelling device is set at.

In the open loop the information from the O2 sensor is not used to correct the air/fuel ratio (a fuelling devise will be able to control the air/fuel ratio in this state and get it down to 13.6:1) - the open loop operates at large throttle openings, high revs and while accellerating.

Yes.

I fitted the O2 controller on the flat underside of the tank behind the left hand grey panel with a sticky pad. The Kev mod is quite small and I dare say could be sqeezed under the seat, but you can lengthen the two wires very easily and mount it practically anywhere. Some folk have mounted it by the dash so it can be adjusted on the move. You'll be able to get it in somewhere for sure.

The break in point is just above the engine on the left side of the bike (as you sit on it) I have the O2 tuner cable tied to the long bolt that holds the tank on. The red light puts sort of a red glow all over the engine in the dark, looks weird!

It doesn't go under your seat, not sure the cables would reach. Takes about 5 minutes to fit from start to finish, and you can remove it just as quick if you want/need to.

Yeah, I first fired mine up (with the O2 controller fitted) at night and I thought something had caught fire under the tank!:incon_aargh[1]:

Great explanation guys. I've been hanging around this forum for a couple of years now seeing "closed loop" this and "open loop" that but never really gotten a sense of what it is. Someone should sticky it :p

The XT's fuel injection is explaned in detail in the ASK Kev section.:happy:

Some reading can be done in this thread, http://www.xt660.com/showthread.php?t=14746&page=19

...never was there a better reason to join the XT Supporter's Scheme!