Thanks for asking that question Petenz as I was just thinking about the same thing today.
And thanks Kev for the answer.

Just on one another thing Kev, would I be correct saying that the O2 controller should get rid of that annoying occassional stall.

By the look of the figures you posted it will be much much better when switching from open loop to closed loop.

The main function of the O2 controller is to tune the closed loop, if the cutting out is been caused by the closed loop being to lean lets hope it fixes it, those results unknown at this stage.

Copy below of a message I just sent to Kev. Pretty self explanatory.
Very happy XTX owner !

Also new Dunlop Sportmax Mutants are excellent. May just be because they're new and the old tyres were knackered and mismatched (Michelin fornt ,Bridgestone rear).


Kev,

Its been a long cold and wet winter here in England. I finally got out last week for a couple of hours and was astonished how well the Xtx ran.. It was first proper ride since last autumn with your O2 controller. I also fitted a DNA Stage 2 before the ride and suspect that this has contributed considerably to how well it runs.

No hesitation at low throttle openings making it very confidence inspiring to ride.

Current mods list:- Co set 25 up from standard, Kev mod at +8 degrees, Kev's New O2 controller, K&N filter, DNA Stage 2, Snorkel still in !, MTC Exhaust cans and link pipes,
WHAT A BIKE IT IS NOW ! If Yamaha sold them like this they would be everywhere.

I'm going to leave it pretty much alone as it is now. I might try the snorkel out but it's so good I dont want to tinker too much. It feels like it needs another gear now !

Only one thing still on my mind - other than doing a spark plug colour check how do I know when the Kev mod is adjusted correctly and mixture is not too lean or weak ?

Thanks for all your help - I've finally got the bike I hoped for !!!

As per PM. Thanks for the feedback, glad you have a much better ride now.

You need to adjust the mod as per the mod instructions as they were tested on the Dyno to get the A/F ratio settings & you will be fine, if you need the tuning instructions again PM me your Email address again & I will send them to you when I get home tonight.

Thanks for this information. Most of it is over my head, but nice to read. I installed the Kevs mod to my bike that had the original pipes cut/gutted and re-welded. Was initially happy with the mod, but it was only making a very limited improvement. I have since purchased some new mufflers and link pipes. I am still having issues around the 40-50K speeds with poor fuel delivery, and back firing is still an issue. I have made adjustments from 0.15 - 0.45(imagine a clock face), it's currently sitting at .45. I have just bought a Nitro kit, but after reading this seems a waste of money.
The bike has a stage 1,2 DNA kit, but maybe the holes that were cut in the sides of the air box were too big and the adjustments are not adequate?
Any help would be appreciated

What model & year XT660 are we talking about? As the XT660 that are 2007 model on wards with O2 sensors require an O2 controller to fully control the A/F ratio.

Have you blocked off your AIS pipe to reduce the popping when the throttle is closed.

I would increase the fueling to 8 O'Clock with all your mods.

Fuelling issues
 

My bike had poor fuelling at low throttle openings and also in the transition from closed to low throttle openings such as feeding power in gently when mid corner or low speed cruising. Kevs New O2 Controller fixed this for me.

Your set up looks similar to mine but don't know model year of your bike. Mine is 2009 with Oxygen sensor in the exhaust.

The Kev mod adjusts the fuel mixture to prevent running weak but didn't (can't ?) cure the poor fuelling on its own.

It is worth persevering because the bike is a joy to ride when the fuelling is fixed.

Good Luck.

Thanks for the replies.
2005 XT660X

I saw the bit about AIS and blocked it off. Also adjusted CO up 8 places. Yes Kevs mod is sitting at 45(9pm). I will take it for a ride this afternoon.

Coming from a Ninja 250 this thing is just great. So will try to sort it out. Really want it running nice so I decide if this style of bike is the way forward. But the seating position is god dam brilliant. No pain in the wrists or arms any longer and more road presence.

02 Controller? Haven't seen that.

2005 XTX ECU info, if you have a 00 ECU is is very hard to get rid of the surging, a fuel mod will help but you will never get a perfect ride with a 00 ECU.

http://www.xt660.com/showthread.php?t=8546

Also check your rear sprocket holder rubbers there should be no free play in them, what is the condition of your chain & sprockets?

Checked the ECU, it's 5VK-8591-01.

Took it out Yesterday, with CO up 8 places & AIS done. Seems to be better. Have increased the CO up another 2 to make that 10 in total. Any limits on that increase? Still getting a lot of back fire. But that doesn't really! worry me too much. It's more the fuel delivery.
Will get back on how this runs again.