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Thread: Big end banging

  1. #16
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    Quote Originally Posted by aware View Post
    Another mystery is that the right sprocket if the chain jumped one tooth then the mark should be lower by one. Mine is higher.....
    Did it kick back and try to counter rotate?

  2. #17
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    Today I timed correctly the sprockets and no improvement, maybe even worse.

  3. #18
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    I have no idea. Most probably it was wrongly timed already by me last time I checked valves.

  4. #19
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    I said I did not have high hopes on the timing being the solution. Obviously you reset the valve lash while you were at it. How did the oil pump look when you inspected it? Nice and clean or gunked up with cooked on oil?

    You could still have a partial blockage and since you have been running it the chances of collateral damage has greatly increased.

  5. #20
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    Oil pressure test showed same behaviour like my second same type bike (much younger only 20.000 km's).
    I will focus first to camshaft and sprockets (maybe slipped), then chain guides (remove to inspect) BUT makes sense that something still maybe blocking the oil passages or the oil pump. So next move would be to remove the oil pump.

  6. #21
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    check the valves, the oil pump and other moving parts
    also check the crankshaft and piston rod for wear

  7. #22
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    Quote Originally Posted by aware View Post
    Oil pressure test showed same behaviour like my second same type bike (much younger only 20.000 km's).
    I will focus first to camshaft and sprockets (maybe slipped), then chain guides (remove to inspect) BUT makes sense that something still maybe blocking the oil passages or the oil pump. So next move would be to remove the oil pump.
    It showed the old one when cold jumped to a high that was almost double of the one that appeared to be running correctly if I am remembering correctly.

    Cold idle:

    Problematic bike starts with 0,8 and quickly climbs to 3,4 bar
    ...../ Other bike starts with 0,5 and climbs quickly to 1,65 bar

    High cold pressure readings yet extreme knocking when warm could be a blockage and even once that's cleared you may find extensive wear on the parts Jog mentioned.

    Those Rotax engines tended to self destruct when pushed to their limits. To me they should have restricted them a bit to ensure long life as many will push them past the reasonable speed of 55/60 mph just because the engine will let them.
    Last edited by Rockynv; 10-14-2018 at 10:34 PM.

  8. #23
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    I was never pushing the bike (max 50 kmh) since I was aware of the vulnerability of pressing it.
    Correct point that this high pressure upom startup is somenthing that needs investigation.
    Today I will start stripping out parts to get a closer look (camshafts, flywheel, oil filter).
    I wonder if any gasket bit has broken and got stuck somewhere.

  9. #24
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    Thanks for the insightful replies, today I discovered some bad to horrible things:
    1) Staples were attached to the flywheel and TDC sensor. How on earth these entered the system is very mysterious (same with ones I have in garage; my little boy threw them in oil container?)
    2) Oil filter is full of aluminum paste. No idea what this is. Look at pic with filter on my gloves, the paste is on my fingers
    3) Magnetic screw had a lot of black particles (very thin ones like dirt) which is peculiar given the fact that I washed it some 100 km's ago.
    4) Timing is OK with TDC screw in place.
    5) I jog the flywheel and realise that rod and crank move together and present no slack (this is the only maybe positive news)


    Seems one-way street that I must at least remove oil pump to check.


    https://drive.google.com/file/d/1-Z1...w?usp=drivesdk


    https://drive.google.com/file/d/1-xH...w?usp=drivesdk


    https://drive.google.com/file/d/1dcW...w?usp=drivesdk


    https://drive.google.com/file/d/1iEo...w?usp=drivesdk


    https://drive.google.com/file/d/1FZh...w?usp=drivesdk

  10. #25
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    That aluminum paste is unfortunate as it points to severe wear to the piston skirts, main bearings or potentially the camshaft bearings. Yes a flaky gasket or a errant glob or gasket sealant could have come loose and be at the root of it all.

    If the main bearings cast into the case halves have been scored its usually considered a total loss since there is not enough material there to bore them out and press in a reliable insert.

    Any chance some vandal poured something into the crankcase?
    Last edited by Rockynv; 10-16-2018 at 07:11 AM.

  11. #26
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  12. #27
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    Quote Originally Posted by aware View Post
    Jog it without the pointy bolts to eliminate the sound of them wobbling in the alignment holes.

    You had aluminum paste in the oil so something was ground up pretty badly and you really need to keep digging until you find the damaged parts.

  13. #28
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    The next step is to remove oil pump and water pump (last thing changed and close to the time the whole thing started messing with idle).
    Seems that at the time I changed oil during water pump change, the wire staples entered the oil and this may be related to the abnormal oil pressure behaviour (oil light flashing at idle) as well as the bad idle (crank sensor possibly affected by those staple wires attracted by the flywheel).
    Even all this alu paste can be a result of those wire staples grinding into the oil pump.
    I wonder if the chain jumped a tooth too because of this.

  14. #29
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    Today I opened oil pump and found it in very good condition.
    However, these wire staples scratched badly the flywheel and slightly the crank sensor.
    Water pump in mint condition too.
    This means that all signs lead to something wrong with the rod and will open little by little to check.
    Will keep you posted.
    BTW my son had no idea about these wire staples, so most probably I have been a vandalised. This damn dipstick can't lock and this can bring lots of troubles.
    https://drive.google.com/file/d/1ad9...QMeReC4g1/view
    https://drive.google.com/file/d/1FUS...mApnuuGiz/view

  15. #30
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    I opened head today. Half valves are brown! Some brown liquid too?
    I checked piston slack too. Marginal slack (check video below).
    Head gasket blown?
    Piston slack normal or not?
    Thank you


    https://drive.google.com/file/d/1-Vv...w?usp=drivesdk
    https://drive.google.com/file/d/1-W7...w?usp=drivesdk


    https://youtu.be/5KclvV9RrFs

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