Hello.

I am a new owner of a xt660x from 2004.

I have read alot in this forum and want to get some clarification regarding the fuel mod.

My model does not have the o2 sensor but does it have open and closed loop? If the engine cant read the oxygen levels of the exhaust it should not be able to correct it either. Right? So my ecu is therefor open loop all the time?

The fuel mod, from what I have read, adds resistance in serial of the tempsensor in the airbox? Fooling the ecu to richen the mixture compensating for colder temp.

My bike runs great when engine cold and running on choke. When engine gets warm it gets more uneven when cruising and not as alert on throttle.

Would a fuel mod act similar as the when the engine is cold?

Firstly... Welcome on board!

Yes

It will certainly help! When the bike's cold it will run a richer A/F then when hot. The fuel mod will allow you to richen up the A/F ratio when warm, so achieving a similar effect - smoother running and more power.

Get one - you'll not be disappointed!

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Thank you, just the type of info I was after.

Welcome mate, here is some further info for you.

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

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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