Please help - high oil consumption

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by RedRupert, Feb 7, 2013.

  1. RedRupert

    RedRupert Brit in the Soviet Union

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    Thanks. I will answer so that there is a record of what I've done etc.:

    I used a Flex-Hone to hone the bores in accordance with the manufacturer's recommendations and instructions. I used the 240 grade Aluminium Oxide version, which produced a nice light and even cross-hatched surface. I used WD40 to lubricate, and ran the tool through the bore with quick strokes for only 20 seconds. It does not look as if I've ruined the cylinder - remember that it drank oil before I honed, as well as after. Flex-Hones should not be used in two-strokes because of the ports.

    [​IMG]

    This is the result:

    [​IMG]
    #21
  2. charlie264

    charlie264 Long timer

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    Good on both, the compression test is showing 16 bar. I think the lc8 is rated at 11.5:1.

    Is there oil on air filter, if you’re not loosing oil down the guides and seals and no oil is being blown on the filter, I would say due to your resent top build its just burning the oil. My lc8 burnt oil till 9k miles, then stopped.

    Plug looks fine, not oily and just looks like the engine is running a little rich.
    #22
  3. WRW9751

    WRW9751 7th Day Adventurist

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    I'm with Dave he's spot on!
    #23
  4. ragtoplvr

    ragtoplvr Long timer

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    The leakdown is too high.

    You need to run the leak down and listen at the crankcase vent, if it is going by the rings you will hear the air escaping.

    Sometimes you have too much blowby and overheat rings, they lose temper. 30 % is too high. When this happens you have to install new ones. You oil will turn black very fast if this is true

    Sometimes rings crack, this can be from installation or from excess piston groove wear. Rings can also be put on upside down

    Rod
    #24
  5. Boatman

    Boatman Upward and onward!!

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    I agree also. What the OP may have accomplished is makeing the bore even smoother in the end. Thus the same or worse than before.
    #25
  6. Orange Toaster

    Orange Toaster Been here awhile

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    Looks pretty normal to me.

    /OT
    #26
  7. baloneyskin daddy

    baloneyskin daddy bikaholic

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    If you think using thicker oil is the answer you're ass backwards as it is harder for the rings to wipe off the thicker oil. Try going to a lighter oil it takes less power to circulate and may even improve gas mileage a little.
    #27
  8. pdxmotorhead

    pdxmotorhead Been here awhile

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    Yea,, it does not take very long at all to seat rings when everything is right.. 30 weight non detergent oil can be found at marine suppliers sometimes in my country.. as hard and sharp aas nicasil is I'd expect less than 100 miles ot bed the rings, sometimes some mild lugging for 2 or three minutes will help..

    On a engine with forged piston and aluminum bore the leakdown needs to be done as soon after stopping as possible, you need the motor warm. The forged pistons loosen way up when cold.. The cosworth I mentioned would go from 30% cold to 5% hot.. :)

    Cheers

    Dave
    #28
  9. Racer111v

    Racer111v Been here awhile

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    I can't report on KTM 9xx pistons, but I have seen worn 1st/2nd ring lands causing oil consumption in automotive and motorcycle engines. They also had good compression and moderate leak down.
    #29
  10. walstibsf

    walstibsf ADVENTURE-HOLIC

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    excess crankcase pressure or poor/improper venting can contribute exponentially to oil consumption. As before, you sound like you've got your shit together....but something to consider......


    Good luck and laters.....
    #30
  11. azcagiva

    azcagiva new orange flavor

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    I think your rings are not seated all the way. With the fairly smooth cylinder surface and the syn oil it will take awhile (if ever), for the rings to take a complete seat. The top rings have the benefit of cylinder pressure to push them into the cylinder wall, the oil rings do not.

    I have had a few ring seat issues with some trucks in my fleet. The trucks run propane and since the reformulation of oil here in the US we have had issues with new rebuilds. I had to start using a high zinc oil in combination with a rough hone and higher tension oil rings to solve our problem. I am a believer in the break in oil now.

    Regular oil would be a lot easier to try than tearing it down and starting over.

    -John
    #31
  12. Orange Toaster

    Orange Toaster Been here awhile

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    All I'm saying is that when I ran my 950 with 10W-40 oil it used more than when running the KTM recommended Motorex 10W-50.
    I am not saying that it have to be Motorex, now (20,000+ kms later) I run private label 10W-50 and it is using around 0.1-0.3 l/1000 kms subject to riding style. Bike has now done around 66,000 kms. Mostly touring.

    /OT
    #32
  13. adcolor

    adcolor Adventurer

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    Not to avoid troubleshooting your rings. But.

    I presume the LC8 has smooth rod & crank bearings. If they are loose enough, the big end of the rod bearing can spray oil onto the cylinder walls, overwhelming the oil ring. No suggestions on how to determine that w/o a tear down.

    Does this engine design have a cooling jet of oil that sprays the under side of the piston? If so, how is this regulated?

    Good luck.
    #33
  14. RedRupert

    RedRupert Brit in the Soviet Union

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    Yes, I'm going to try using straight 30W oil as you and Dave have suggested, in order to seat the oil rings.

    Please can you give me some advice on:

    a) The best oil and how to find/identify it - API standard S?

    b) The best way to seat the rings, and what to avoid doing.

    Thanks for your help,

    Rupert
    #34
  15. RedRupert

    RedRupert Brit in the Soviet Union

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    Thanks for your advice. I was reluctant to accept it at first, partly because I was annoyed with myself - I did know that synthetic oils are no good for running-in (I've read about the problems Yamaha had a few years ago). I made a half-hearted effort to find a suitable oil, but ended out settling for semi-synthetic.

    There is too much soot in the exhaust pipes. The oil is being burnt. The valve-guides and the pistons were in very, very good condition.

    Also, as I've said, I led the engine vent pipe into a catch-bottle - rather than into the top of the air-box. Since doing this, the pre-filter has been very black, and so was the front of the OE paper air-filter before the pre-filter was fitted - almost as if there's too much oil in the air around the air-box intake.

    I'm going to try using straight 30W oil as you and John have suggested, in order to seat the oil rings.

    Please can you give me some advice on:

    a) The best oil and how to find/identify it - API standard S? (what suffix if any to go for?)

    b) The best way to seat the rings, and what to avoid doing.

    Thanks again,

    Rupert


    Re the leak-down: I ran the engine 'till the fan cut-in before conducting the test, but was surprised to see that the readings were very close to the ones I'd taken while the engine was cold. I should try it again.
    #35
  16. charlie264

    charlie264 Long timer

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    Rupert, I spoke to Bob Presslee ex KTM machanic. He said try 10-40 mineral bike oil for a couple of thousand miles, he added they had a SD that kept burning a lot of oil, the guy sold the bike and the new owner took it on a few track days and that cured it.
    #36
  17. RedRupert

    RedRupert Brit in the Soviet Union

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    :D KTM true to their word then! Really, Ready To Race!

    Thanks for the info. I'll use some mineral oil, but it'll be a while before I know the results, as we'll have snow and ice on the ground until the end of April!

    How should I ride it with the mineral oil inside - plenty of acceleration and engine breaking, or thrash it?

    I do thrash hell out of my bike - it's only used abroad while on holiday. Never any commuting, touring or pootling, I promise.
    #37
  18. azcagiva

    azcagiva new orange flavor

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    Rupert,

    In the US, the EPA made the oil companies reformulate the gas and diesel oils, they took out the zinc and some other stuff. I imagine since you do not have the EPA to deal with your dino oil should have higher zinc and other good things for engines. A good 30 wt, or similar diesel oil should work in a pinch. I use Maxima break in oil and have had good luck so far with it.

    As far as what not to do I would wait for the engine to warm up to give the pistons time to grow. I would then flog the piss out of it and hope for the best. If that does not fix the high oil consumption I would just live with adding oil until the next rebuild. ( Which is what I am doing with my ducati at the moment:D).

    Let us know how it goes and good luck.

    -John
    #38
  19. Pistolero

    Pistolero W. F. O.

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    :ear:lurk
    #39
  20. AdvRonski

    AdvRonski They call me......Ronski

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    I replaced the rings on my 2004 950, and honed the cylinders with the same type of hone. I also added the crankcase vent valve that did not come on the early bikes. I had no issues with ring seating, and oil consumption is quite low.

    [​IMG]

    However, the picture of your cylinder shows the angle of the cross-hatching is way too shallow. I am a professional auto technician, and have found honing properly takes a while to get the hang of. It appears the you had the hone rpm too high for the frequency of your up and down movement. The ideal angle is 60 degrees between the up and down lines, while yours appears to be about 10 degrees. Hopefully some break-in oil will help seat those rings without another tear-down.
    #40