A reply from Dyno Jet today.

While testing this bike over the last month or so it has become apparent we cannot disable the O2 sensor with the eliminators we already have, we also found just disconnecting the O2 sensor caused a lot of problems, chiefly the bike will cycle very rich during cruise situations.

We are currently working on a solution, however as it isn't going to be an immediate answer we have decided to release the XT660 power commanders with a note attached explaining that:



"Due to the close loop emission system used on the above bikes it is not possible to make fuel changes with the power commander between 3500 and 6000 RPM, below 20% throttle.
It is not recommended to disconnect the O2 sensor on these bikes."

The surging in caused by the bike running too lean during cruise situations. We have not "contacted Yamaha".

Hope this clears a few things up.

Martin.
Dynojet UK
01995 600500
www.dynojet.co.uk
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When I get on the Dyon next I will do some testing with the PCIII. I do not think I will be running my O2 sensor with my PCIII for now, it does not make sence to me.

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Mods that I have done to my XTX's

My 04 XTX
Stage 1 & 2 DNA filters / Kev fuel mod / snorkel mod / Drilled air box mod / Engine breather mod / Fork Spacer mod / 15w fork oil /
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My 07 XTX
Raptor 700 cylinder 102mm / Modified Crank Case to take a 105mm Raptor Cylinder / 11:1 102mm JE Raptor piston / Stage 1 Raptor Hot Cam / Ported head / Colder Spark Plug / +2mm Throttle body / DNA stage 1 & 2 filters / Modified Air Box / Snorkel removed / Worry Brothers stage 2 filter cover / 6mm & 8mm Bolts Replaced with Titanium Bolts / Recovered seat in Black / O2 Eliminator /

My 09 XTX
59HP at the rear wheel / Stage 2 Raptor Hot Cam / DNA stage 3 Air Box / Carbon Can Exhausts / Modified Exhaust Link Pipes / PCIII With Custom Fuel Map / Wideband Commander O2 Data logger / LCD100 Dyno Jet display & fuel adjuster / 2500 OHM HT lead instead of a 10K OHM XT lead / Extra Coolant Cooler / Protaper Fat Bars / Tail Tidy With LED Tail Light / OKE Protection Knobs / LED indicators / AIS blocked / Modified rear sprocket rubbers / Rear Foot Pegs removed / 09 ECU With 02 Sensor Changed To A 06 ECU / Complete wiring harnes Changed from 09 to 04 / Home made LED resistor flasher / Hole drilled in the fuel tank filler neck to allow quicker filling / Modified Bar End Weights / Progressive front fork springs, 15W fork oil, forks lowered 25mm, used XTR rear links lowering the rear 20mm, rear spring one click stiffer / Changed front & rear guards from blue to black / 47T rear sprocket / Speedo Healer V4.0 / Kev throttle cam mod / Throttle grip mod / The new 2010 O2 sensor mod is out, works a treat, The new 2012 O2 Controller is out, PM me for details

Now ride a 2018 MT09SP ABS + TCS

My KTM 990 SMR Mod book. http://www.ktmsmt.com/viewtopic.php?f=13&t=4946