Hi, I'm a long time member of the forum and proud owner of a 2004 xt660x, and i'm writing from Italy.
During last year I've tried many possible solutions to minimize the typical on-off problem of this bike.

These experiments just ended with a new type of fuel mod that i think could be interesting for the community.
The main problem with the classic fuel-mode obtained adding a trimmer ins series with the NTC is that the correction is not linear due to the non linear behavior of the NTC.

In fact for instance a 1kOhm correction changes the temperature read by the ECU by ,more or less 5�C when the real temperature is 10�C and by over 20�C when the real temperature is 40�.
This causes an engine behavior that's changes together with the outer temperature.
It would be much better to have a linear correction over all the temperature range.

This is possible by adding another NTC in place of the trimmer.
To guess the correct value of this NTC you can simply:
- measure the resistance of the original NTC @ 25 �C (1.9Kohm fom me)
- found the optimal correction (in Degrees) that allows your bike to run smooth (form me is around -5�C)
- put a resistance or set the trimmer to obtain that correction (around 500 ohm for me)
- Buy a NTC with the correct resistance @25�C (i've bought a 470Ohm @ 25�C NTC)
- Put the NTC in series with the original one and put it on the air flow (another hole in the snorkel?)

That's all.

This type of mod is not comparable to a system like a power commander, but works much better than a single trimmer for me.
I'm sorry if my english is not so good but i hope my explanation will be understandable and useful for you too.

Gabriele

Grazie Gabriele, noi ti capiamo e apprezziamo i tuoi suggerimenti.

Cortesemente, manda un private message con il diagramma e le specifiche delle resistenze usate al nostro esperto meccanico Kev cosicche' lui potra' fare delle prove e verificare se funziona uniformemente su tutte le XT.

Grazie ancora e cordiali saluti.

Ottimo, la lingua ufficiale � diventata l'italiano?:-) tempo di fare qualche foto e recuperare i diagrammi e mando tutto, magari in serata o domani

No la lingua qui' e' sempre l'Inglese pero' sei fortunato che io sono italiano.

This mod has been around for a few years now.

I have tried this mod before & the only draw back with this mod is it can not be set for a wide range of mods when you are trying to market a fuel mod.

You need a different NTC resistor resistance for different mods, fuels, altitudes & temp all require different resistances, so one resistance of NTC resistor will not work for everyone around the world.

The mod works well if you know the exact resistance you need for all your mods.

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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

Thanks Kev for your clarification