Just found out (despite my dealers assurance of otherwise) that the Yamaha XT660R '07 with lambda probes, cannot run on leaded fuel.

Models prior to '07 should be able to run with no problems.

A "fix" is being researched and I'll let people know in the XT forum. Just a heads up in case you were considering purchasing a brand new '07 model for your overland trip.

If I missed a post regarding any solutions to this problem, could you perhaps direct me to it?

That's a PITA. What's the problem?

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What's a PITA?

Pain in the bottom.
Or some similar word for bottom.

PITA...haha. Ok, got it .

Anyway, Tim, the problem is that apparently the '07 lambda fitted xt660r models cannot tolerate leaded fuel exhaust. Not only does leaded fuel cause havoc to your catalysts (they'll die) but apparently also to the lambda probe. Driving a bike with no catalysts is not a big problem, unless you're an enviromentalist buff. I've heard that you can deliberately "kill them" and not care. Or you can avoid the situation completely by fitting some after market exhausts. But killing off your lambda probe is a definate no no. To be honest I realy have no idea what kind of damage it could do (if any) on the engine itself. But happily riding across Africa with the engine warning light on, is not a prospect I'm looking forward to. The lambda probe is there to ensure correct fuel/oxygen ratio. If it doesn't work, I can imagine the mess it'll do to your fuelconsumption. Or the other scenario, failure to give the output needed to actually drive.

That is the problem in a nutshell. It's propably even more complicated than I have knowledge to explain.

Keep in mind that this is only a problem because I wish to venture into parts of the world where leaded fuel is the only available option (Africa). Had I not planned to leave the boundries of the western world, I would propably never have realized this problem. Regardless, it's definately a PITA .

Just to confirm......

My '04 XT660R went for many a good mile in Africa using only leaded petrol. That's all there was at times. Admittedly, fuel consumption did suffer a bit, but that may also have been due to an unrelenting headwind and trying to keep up with a 1200 GS!
It is still going strong, but these earlier models do not have a lambda sensor, as the later ones do.
If planning a trip where there is likely to be no unleaded, get yourself a model before the '07.

According to Wikipedia (Oxygen sensor - Wikipedia, the free encyclopedia) the lambda sensors can be damaged by as little as a couple of tankfuls of leaded fuel. Which is a bit worrying as I've done more than that on my 1200GSA (and did on the 1200GS I had before). Am I being hopeful in thinking that somehow my 'RTW BMW charriot' is less sensitive to leaded petrol compared to other bikes?

Tim

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and enlarges the world in which you live," Irving Mather (1892-1966)

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Beemers are fine apparently. It'll sensor (geddit?) the change and alter the fuel mapping accordingly so as to not stuff up the engine. The only thing you need to be aware of is that you're more limited to the fuel octane rating now.

Hello there,

Having a XT 660R '05, I wondered "what is an oxygen sensor or a lambda probe?" and "what happens if it stops to work?". The answers I found is summarized below for riders in need to know

- An oxygen sensor, also known as lambda probe, is a device to measure amount of oxygen in exhaust gas and sends signals to engine control unit (ECU). Then, ECU adjusts the amount of fuel injected to provide the optimum air-fuel mixture.

- Reading below references, I found that if this sensor stops to work, then the engine continues to operate using a "over-rich" mixture to protect itself against "lean" mixtures. And that increases the fuel consumption.

oxygen sensor: Information from Answers.com
Howstuffworks "How does the oxygen sensor in a car work?"
+ the Wiki page Tim Cullis provided before.



So, this post became my first in the HUBB, greetings

Coskun

That is correct. Although an overrich mixture will not damage your engine as such. It will choke up the plug and hasten carbon deposits on the bore and valves.

Bad move by Yam if they are selling the 660 an an overlander (which they are)

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Tim, you should definately check with your mechanic before assuming that your lambda probe is tolerant to leaded fuel (indefinately). From what information I have gathered, such a probe does not exist. And as you've discovered yourself, Wikipedia says the same due to how a lambda works. According to my mechanic as a rule of thumb, a lambda can operate on leaded fuels for about 40-50 hours before failing. Sometimes more, sometimes less. I'd strongly suggest talking to a pro regarding this. Who knows, tolerance may be model dependant.

But whatever damage your lambda takes or doesn't take from leaded fuel exhaust, is not eliminated by remapping the fuel.

Just found a relevant thread on UKGSer re BMW sensors,

__________________
"For sheer delight there is nothing like altitude; it gives one the thrill of adventure
and enlarges the world in which you live," Irving Mather (1892-1966)

Access the Morocco GS Knowledgebase

Great Tim. Can't beat hands on experience. Sounds like your worries are over .

I'm guessing destroying the lambda will shave off a few miles of your MPG. I mean, BMW (and Yamaha) put it there for a reason. But it seems that the MPG cost is neglegable. Running on dodgy fuelquality will propably do that anyway.

As for the xt660r, I'm going to test it this weekend to see what the effects are by disconnecting the lambda. I'm guessing it will consume more fuel. How much more and if it's neglegable like on your bike, time will tell.

I'll come back to this thread when I know more.

Hmm, very interesting McThor,
As I understand these things, those "exotic" fittings, like Lambda probes and cats, are there for European legislation requirements (another example: it has been proposed/discussed by the Eurocrats to introduce legislation to ban after-market exhausts on bikes).

Naturally this takes no account of the majority of the world!!
I suppose this is all part of that age-old discussion about high-tech Vs low-tech bikes for 3rd world countries.

Anyway, why destroy these fittings, when it may be better to remove them (lots of cats have been chucked) for a journey with the option of refitting them later?

Dave

ps A bit confusing; this topic is running on 2 threads!!

pps reference your first posting: I have just about had enough of dealers who employ suited salesmen who know naff all about bikes - why do dealers think that I would be inclined to talk with them, much less buy a bike on their advice or assistance!?

Yeah it is a bit confusing with two threads. My bad .

Just to clarify; I don't think that the lambda is there due to enviromental legislation. I think it's there for better fuel mileage. That cat however is mandatory.

As for killing off the cats, I'm getting conflicting views and oppinions eventhough everyone agrees that they will "die" from overheating when running on leaded fuel. Some say that it may clog up and eventually impare performance (they do admit that this is only theory. Not hands on experience). And others again say that it wont matter one bit, apart from the fact that the exhausts now emmit particles that were otherwise filtered out.

I'm still debating with myself whether or not I am going to fit aftermarket ones without a cat. I don't have enviromental qualms with killing off the stock ones. I am just a bit worried about the clogging issue. Even if it IS only a theory.

And about the suits selling bikes; I totally agree. I'm a lot wiser now with regards to gathering "expert" advice. Ofcourse the suit in question was not my only source of information. But with regards to the '07 model he was the natural assumed "authority" since other sources of info on such a new bike is limited. Knowing what I know today, I would propably have bought a '06 model without the probe.

Having said all that, I am still happy with my choice of bike. The probe is just a "snag" that is seemingly easy to solve/overcome. But I'd have prefered not having to deal with it at all, ofcourse .