Hi folks, I'm trying to get my head round all these mods and kinda struggling a bit.

There seems to be a Kev mod, an o2 thing and what seems like various different filters.

So can someone explain them in plain english, and please don't send me links to Kevs page as I honestly can't make head not tail of it all.

Can someone also tell me how much these mods will cost me if I purchase them

Many thanks.

Now if I remember right, you have a Tenere. So here's what applies to you...

O2 Controller

Without getting too technical, this little box plugs in line with the bike's O2/lambda sensor and sends a signal to the ECU telling it to set the air/fuel ration to 13.6:1 under certain conditions (idle and at lower engine speeds for example). In other words when the ECU is running in the "closed loop" and fuelling is dictated by the O2/lambda readings. At all other times the ECU runs in an "open loop" and fuelling is controlled or set by a combination of other sensors, conditions and factors. In stock trim (without an O2 controller fitted) the XT660 runs too lean in the closed loop (up to 14.7:1) which can result in surging, poor throttle response and a lack of power.

Kev Mod

This little box with a rotary knob helps to set the fuelling in the "open loop", or when the O2 sensor is not being read by the ECU. It fits in series with the air intake temperature (AIT) sensor and basically increases or decreases the voltage reading the ECU receives from the AIT sensor. By increasing the resistance (turning the knob clockwise) you richen the fuelling and by rotating anti-clockwise it has the opposite effect. When in the zero position the fuelling in the open loop is as it would be as stock. The reason you might want to fit a Kev Mod is to compensate for the extra intake air flow provided by an aftermarket filter/filters - the more air flow, the greater the fuel needed so the knob should be rotated clockwise to compensate.

Air filters

Here's what DNA filter options you have available. As you move down the list, you get more air flow and there will be a greater need for fuelling adjustments:

= Stage 1

+ = Stage 2

+ + = Stage 3

With a stage 1 filter only, there is no need to adjust the fuelling, the ECU will cope with the change. However, as the XT already runs on the weak side of what's acceptable, you won't maximise the potential of the increased air flow without adding a little more fuel.

The stage 2 requires a Kev mod to richen things up, or the motor WILL run lean. There are a good few horses to be released from the stable with this filter and a correctly set Kev mod.

The stage 3 increases air flow further and requires even more fuel, but with further benefits in terms of horsepower.

There is also a restrictor insert you can fit in the Stage 2 top cover to effectively makes a Stage 1.5, which would be as far as you could go with out fitting a Kev mod and modifying the fuelling to suit.

I hope this helps? I've tried to keep it as straight forward as possible for you.

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Thanks, appreciate it.

So can you tell me costing for lets say, a kev mod/an o2 thing and a stage 2 filter, as I presume that they would be needed together. Oh and where does one get all these things ??

Filters: Best place to get them is from BR Special Tuning.

http://www.motorcycle-exhausts.co.uk/Yamaha_DNA_Filters--category--785.html

Kev Mod/O2 Controller: Best price can be obtained from Kev directly by send him a PM. He does sell them on ebay, but they'll be a little more expensive to cover his ebay fees.

http://www.ebay.co.uk/itm/Yamaha-XT660X-XT660R-XT660Z-XTX-XTR-XTZ-O2-Controller-Fuel-Mod-/141627590325?pt=LH_DefaultDomain_15&hash=item20f9a 986b5

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