Help, my 990R has become a 2 stroke!

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by Martynho, Nov 3, 2012.

  1. Martynho

    Martynho No more Chilegringo.

    Joined:
    Mar 16, 2010
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    2010 990R with 62,000kms on it started burning 1 litre of oil per 500km after a trip to Bolivia! I limped it 1500kms home topping up as I went along

    Got home and had it checked out by my friendly neighbourhood mechanic (he is a Dakar and ISDT mechanic)

    Evidence of some oil in the airbox
    Valve guides shot - replaced with some we had made locally in bronze
    Valve seals shot - replaced
    Rings showed some wear but not critical, we replaced them all anyway

    Just got it back running a few days ago so took it out for a run yesterday

    Still burning oil, like 700 ml in 300 km, oh and the idle kept going up to 2k, then 4k, then settled down again.

    Does anyone have any pointers as to where we go next? He is puzzled also despite his 20 years + experience

    Going back in the shop Monday. As I use my bike for commuting my mechanic buddy is kind enough to lend me a new KTM200 Duke, that should be a laugh in city traffic! :D

    Appreciate any advice
    Thanks - Martyn
    #1
  2. Peanuts

    Peanuts Long timer

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    Balancer shaft seal (inside the generator/starter cover)? Cheap and easy to change.
    #2
  3. Martynho

    Martynho No more Chilegringo.

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    Thanks mate, I have seen that on here before and we will do it first thing Monday. Question is....will an oil leak from that balancer seal go into the combustion chambers or just soak your air filter?

    Started it up this morning and there is a lot of black smoke in the exhaust over 4000 rpm

    BTW there are no leaks anywhere.

    Thanks - Martyn
    #3
  4. LukasM

    LukasM Long timer

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    Unfortunately I don't know the oil circuit of the LC8 well Martyn, but with Kevin aka Mr. Peanuts you are in very capable hands. :1drink

    Did you check the pistons thoroughly when you had them out? How about the coolant, any trace of the oil or is it clean?
    #4
  5. Martynho

    Martynho No more Chilegringo.

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    Thanks Lukas. Never had a problem with the coolant now or before the new p rings and valve guides, clean as a whistle.

    Pistons and bores were in great shape, well within spec

    BTW mate, as I cant ride the bike you will be pleased to know I am just sat at home, sweating in 30C heat, drinking a pisco sour with Katie waiting for the cow on the parrilla to get to its punto! :yum:yum:yum
    #5
  6. StmbtDave

    StmbtDave AKA Invisible Dave

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    Balance shaft seal should only oil your filter. I can't imagine there would be anywhere enough oil going through the breather hose to make it into the combustion chambers. Did you change the valve seals when you did the new guides? Bad valve seals can suck a lot of oil.

    Dave
    #6
  7. Martynho

    Martynho No more Chilegringo.

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    Thanks Dave. Yep, we changed the valve seals when we did the guides, they were pretty knackered when they came out.
    Is there any direct connection between a balancer shaft seal and the combustion chambers?
    #7
  8. Rafagas

    Rafagas Rafagas

    Joined:
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    Cambiar aceite cada 10000kms, no andar bajo 5000 rpm no mecanicos jamas.

    Probablemente quebraron los anillos al ponerlos, las guias cambiadas no tienen el ajuste preciso, tu problema Martin es mucho mal mecanico........................

    Mandasela a Sebastian yo le ayudo con un cincel y martillo a repararla.

    Saludos
    #8
  9. MortimerSickle

    MortimerSickle Semi-Adventurer

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    Not exactly a direct connection, but the breather hose will drip a good share of its spew into the front carb.
    #9
  10. Martynho

    Martynho No more Chilegringo.

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    Casi todos con quienes he hablado hechan la culpa al Roland por maltratarlo durante sus primeros 9.000kms de vida :rofl

    #10
  11. bloc

    bloc Been here awhile

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    Since most of the oil coming out of the breather hose would go into the front throttle body, maybe check to see if the plugs look different front to rear? Surely that kind of oil consumption would leave evidence on the plugs..

    I'm not familiar enough with the 990, but on my 950 oil can go almost directly from the breather hose into the front carb inlet via gravity and crank case blowby air flow.. anything getting onto the filter is spray or what has run down the top and side of the box.

    All blowby gases must go through small holes drilled radially in the left counterweight, which should have significant centrifugal effect. If that balance shaft seal is bad, however, you lose this system built into the breather to "sling" the oil out of the airflow.
    #11
  12. Rafagas

    Rafagas Rafagas

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    Ta muy viejo, no es capaz ni de maltratar a la Jenny, yo le compré la Naranja con 30k kms y con más de 100k sigue superando los 200, es problema de chofer y mecanico no mas
    #12
  13. Martynho

    Martynho No more Chilegringo.

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    Stripped it tonight and sure enough the new air filter is black at the front and damp with oil, evidence of oil in the front throttle body and butterfly. Not sure it looks like a couple of litres have gone through there. Would it have gone through mostly as mist and then burnt?

    Opened up the casing and the seal is shot. Replacing in the morning and will change out the front plug while we have it open

    Did not smoke when we ran it without the airbox and breather hose on so I am keeping my fingers crossed we have the fix in hand.


    Thanks for all your help guys

    #13
  14. LukasM

    LukasM Long timer

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    So did the seal solve the problem? :ear
    #14
  15. Martynho

    Martynho No more Chilegringo.

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    Went ok for 300 kms, but then it developed a fuelling problem. Erratic Idling going between 2000rpm and 4000rpm!

    Took it back in to get that sorted, put a new fuel pump on it, just got it assembled and now the fucking immobiliser has taken a shit and even KTM dont seem capable of fxing it.

    Grrrrrr!

    #15