F650GS 2002 Single Spark issues / mods / improvements? - Page 2

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Thread: F650GS 2002 Single Spark issues / mods / improvements?

  1. #11
    Bike
    GS/Gd Dakar 2003
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    Oct 2008
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    Quote Originally Posted by Andy.I View Post
    As you were thanks, scratch that - easy enought to find!

    However, when I switched the fuel units from US gallons to UK gallons the average consumption is as follows:

    2002: 63.4mpg
    2006: 69.8 mpg

    This doesn't tell such a rosy story...
    personally think these ave imperial MPG realistic , my single spark from records goes from 60-70 mpg, depending on long motorway runs to Scotland/Lakes or local town runs. I don't dawdle .. . ..
    Twin sparks are a bit more efficient
    2003 GS Dakar
    BMW Panniers, top box, tank bag
    + loads TT stuff that came with it!

  2. #12
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    F650GS 2001
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    Aug 2018
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    Hi Chaps,

    I have checked my plug and can confirm that my GS is definitely running on the rich side.

    I've been reading a lot about O2 sensors and it's all very interesting...

    Apparently the business-end of the sensor is a sintered porous ceramic which allows O2 to diffuse though it to make contact with a pair of electrodes which produce a potential difference somewhere between 0V and 1V, depending upon the level of O2, and this voltage instructs the ECU to increase or decrease the fuel mixture. It makes sense to me that the sensor will have a finite life because its function will depend upon the porosity of the ceramic which will become increasingly blocked by exhaust deposits. While these sensors are supposed to last 100,000+ miles we all know about the bath tub failure curve don't we?

    There are numerous videos on Youtube claiming that we have been convinced / hoodwinked / brainwashed into believeing that O2 sensors fail completely and need to be replaced, rather than regularly cleaned - possibly becauase it's a quick and easy fix - although this is relatively easy process. These videos O2 sensors being soaked overnight in petrol, thinners, carb cleaner etc and then residual deposits being removed by an ultrasonic cleaner. A general recommendation is that they should be cleaned every 10-15k kmiles, ie at every service. This makes sense to me because the porous ceramic will eventually become blocked with all the carbon and whatever deposits in the exhaust, and that regular cleaning should slow down the blocking process.

    As it looks as if my O2 sensor is not working properly I will try cleaning and report back my findings.

    Has anybody else any experience of this matter to add to the thread?

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  4. #13
    Bike
    F650GS 2001
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    There was another fall at the first hurdle yesterday!

    JayDee arrived for a BBQ with a brand new O2 removal tool in his pocket. We grovelled under the bike, slid the tool onto the O2 sensor and it was so slack that it rotated around the hex flats without gripping - a vernier showed it to be 33mm, not 32mm. I sorted out an old 22mm ring spanner and attempted to grind it open but my angle grinder made very heavy work of it so I gave up and decided I needed to buy a suitable tool.

    This leads me to the following question: the various tools seem to fall into several basic designs and variations thereof:

    1) a deep socket like a plug socket but with a slot down the side and 3/8 or 1/2 inch drive square such as Ebay item 190754427966

    2) a flat open-ring crowfoot spanner for either 3/8 or 1/2 inch drive square such as Ebay item 163663425378

    3) a cranked open ring crowfoot spanner for 3/8 or 1/2 inch drive square such as Ebay item 183726054782

    4) a deep open-ring with a pivoting breaker bar such as Ebay item 392534151835

    I can see possible difficulties arising with any of these types of tool due to the awkwardness of access and limited space: would any of you chaps with experience of removing and replacing the O2 sensor kindly advise me as to which type of tool is most suitable please?

    Thanks in advance.

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  6. #14
    Bike
    F650GS 2001
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    I thought I found a definitive answer to my question on https://f650gs.crossroadz.com.au/ExhaustRepair.html and I bought such a tool.

    This morning JayDee and I discovered this tool wouldn't fit because the sumpdrain plug was in the way.

    JayDee had brought his 22mm slogging ring with him but this wouldn't fit either because there wasn't enough clearance between the frame's front down member and the sensor to get it onto the hexagon flats.
    However, we discovered that a 22mm cranked ring spanner could be slid over the electrical connector and with a couple of minutes' heat from a blowlamp the sensor was extracted and the replacement was fitted.

    We reset the ECU, topped up with fuel and set the trip; the engine seems to run just as it did before but I'll judge future consumption from facts and figures.

    More to follow...

  7. #15
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    GS/Gd Dakar 2003
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    Andy I

    have a look at another thread here,' Emissions' if not seen it already,
    Antony put a link which may be relevant
    2003 GS Dakar
    BMW Panniers, top box, tank bag
    + loads TT stuff that came with it!

  8. ThanksAndy.I thanked for this post
  9. #16
    Bike
    F650GS 2001
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    Aug 2018
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    Smile

    I have done 187.4 miles since I last filled up and zeroed the trip, with a mixture of gentle country roads and some rather spirited riding where I was, ahem, making good progress. ;-)

    It has just taken 13.8 litres to fill to the brim again and I make this 62MPG so it looks as if I've had a result and I'm well happy.

    To me the engine's performance was the same as ever but the frugality stands out.

    The only significant thing to report from this experience is that you don't need a special tool; a blowlamp, a bit of alloy as a heat shield to protect the frame's paintwork and a 22mm ring spanner does the job, along with some sidecutters to cut the cable ties and some replacement cable ties.

    While I was at it I degreased the underside of the engine and frame which seem to collect chain oil and I replaced the sump guard torx screws and washers with stainless items.

    Note that my comment about not needing a special tool and that a cranked ring spanner if all one needs applies to my 2002 single spark model although I don't see why it shouldn't apply to a twin spark but as I'm informed that its exhaust pipe is 2mm greater diameter so it is conceivable that this could make a difference. Maybe a twin spark owner can confirm this?

    Thank you for the information and suggestions chaps.


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