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Discussion FZR250 - Cylinder 4 - big end bearing failure

Discussion in 'Yamaha 250cc In-Line 4's' started by simidau, Dec 11, 2009.

  1. simidau

    simidau Well-Known Member

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    Hi everyone.

    We have a few FZR250 (3ln) that we race. I have 3 dead engines currently all the same death. Cylinder number 4. It seems the big end bearing has failed - which usually happens due to lack of oil on the bearing.
    So has anyone had any experience with this, we think one of the crank shafts is ok, the other 2 will probably need to be reground.
    Bearings. Where can I get them from?
    Has anyone upgraded the oil pump in one of these, maybe a larger oil pump with more pressure would stop the bearing wearing out and dying a terrible death <!-- s:) --><img src="{SMILIES_PATH}/icon_smile.gif" alt=":)" title="Smile" /><!-- s:) -->
    Other ideas?

    Cheers
    Simon

    *Edit to big end <!-- s:) --><img src="{SMILIES_PATH}/icon_smile.gif" alt=":)" title="Smile" /><!-- s:) -->
     
  2. dave

    dave Well-Known Member

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    Re: Cylinder 4 - small end bearing

    Thats terrible news...I have not heard of it happening before..

    Small end? - I presume you mean at the piston end of the conrod... Guess there is no oilway through the conrod to there? Just relies on oil being splashed about.. Did you use the same brand of oil on each failed engine???
     
  3. simidau

    simidau Well-Known Member

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    Re: Cylinder 4 - small end bearing

    Sorry.. mean big end. don't know how I wrote the wrong one..
     
  4. alittlegreymouse

    alittlegreymouse New Member

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    Re: Cylinder 4 - small end bearing

    Hey sim, just came across this

    its for the 400s, but it sounds like a similar problem. will keep looking thou

    Source : http://www.fzrarchives.com/fzr400/FZR400 Frequently Asked Questions.html
     
  5. dave

    dave Well-Known Member

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    Re: Cylinder 4 - small end bearing

    That sounds interesting with the oil supply problem.. I take it the restrictor is actually in the crankcase drillings to the mains???
     
  6. simidau

    simidau Well-Known Member

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    Re: Cylinder 4 - small end bearing

    Thank you for that find. All failures have been on an outer big end (number 4 ever time in fact).
    Once we pull a crank out I'll tell you guys how it goes.

    Cheers
    Sim
     
  7. cornulio81

    cornulio81 Active Member

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    Or drive with less angle on left corners <!-- s:D --><img src="{SMILIES_PATH}/icon_biggrin.gif" alt=":D" title="Very Happy" /><!-- s:D -->
     
  8. PhTanJo1

    PhTanJo1 New Member

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    hi dude
    i got the same problem as yours,i race one of my bike and suddenly destroyed the engine,upon dismantling the engine i found the same problem as yours,i posted my problem couple of months ago and dave gave me some decent advice with regards to it,can u update this post if you find the best solution for this one problem especially if you tested it and problems won't occur again,tnx!!!!
     
  9. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    To make it clear what the issue is with the 400s, I have one.
    You may have seen the article from BDK here http://www.bdkraceeng.co.uk/Bike1.html#Ignition this is where I started.

    It states that:
    "If you measure csa(cross sectional area) of oil loss at rod ie:area of pin minus area of rod inc shells, times 2 for both sides . Plus oil loss for outer main brg(since these are fed together). This is the total area for oil loss assuming the crank is not moving(no centrifugal pull). A rule of thumb is that the supply csa is at least a third larger than the loss csa. This also assumes no 90 degree bends etc. If you look at the oil feed in the btm case it has an arduous path to the outer main and consequently the big end. The oil rises in a 5mm drilling (where the restrictor jets are) and then horizontally in a 6mm hole and then up again at 6mm to the outer big end. The 5mm drilling has to be because they wanted to put a M6 thread in it for the jet. Anyway, take the 5mm hole out to 6mm and then use a thread repair, Time sert or Helicoil, to restore the thread for the oil jet. The reason the main is OK is because it always has sufficient oil and little centrifugal force, however the big end throws the oil away at a considerable rate .Remove more than you are putting in and bang! I have seen hundreds of FZR's with outer b.ends gone. All modified as above sorted them out without fail. "


    The procedure as recommended is correct but some simple errors make it a little difficult to follow. For clarity here are my corrections based on my FZR400RR 3TJ1. The feed to the outer mains is not 6mm. The final hole is 6mm but there is a reamed section below that (shown in red on image) that is 5mm.

    First the corrected text:
    The oil rises in a 5mm drilling for main bearings 2 & 5, where the restrictor jets are (2.55mm diameter), and it also branches horizontally in a 6mm hole and then up again at 5mm to the outer main and big end. The 5mm drilling has to be because they wanted to put an M6 thread in it for the restrictor. Anyway, take the 5mm hole out to 6mm all the way to the bottom and then use a thread repair, Timesert or Helicoil, to restore the thread for the restrictor.

    The 5mm gallery (shown by blue arrows) is not large enough to feed both the 5mm main & big-end, and the 2.55mm restrictor.
    [​IMG]
    [​IMG]
    [​IMG]
    As I recall, some forum members have already checked and said that the 250 does not have the same problem.
    Cheers
    Blair
     
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    Last edited: Feb 7, 2019
  10. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    The FZR250 3LN1 oil feed diagram for the crankshaft does not show the same problem.
    OilFeedToCrank.jpg



    With multiple mentions of big end failure on cylinder 4, the first step is to try and identify from the shells and journal what kind of failure it was. If that can be determined I think it will be easy to find a solution. IMHO an engine that runs at 19000 rpm demands that special attention be paid to its lubrication system. If you want to save money on oil changes, buy a Virago.

    Example 1:
    I noticed in the 3LN1 manual the following information
    FZR250_Oil.jpg

    Which appears to be recommending 10W-30 engine oil. Many owners think that it is better to use a heavier grade like 10W-40, but the oil pump output is directly proportional to engine speed. Then it is the job of the pressure release valve to compensate for too much pressure. A heavier viscosity oil is going to open that valve sooner than a lower viscosity, at 18000+ rpm that would be a disaster waiting to happen. I am not saying this is the cause but that these are the kind of things that need to be taken into account.

    https://www.pgfilters.com/blog/can-happen-oil-filter-pressure-relief-valve-fails/

    Thoughts welcome and information from Fizzer owners, which I am not, greatly needed. Then we can fix this problem too.
    Cheers
    Blair
     
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    Last edited: Mar 6, 2019
  11. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    Had two KTM 390 Duke's in at work for high oil pressure warnings. After a lot of stuffing around, the problem was the oil. They had 10w60 in them and the spec is 15w50.

    So the lesson is always run the recommended weight oil unless there is a damn good reason not to do so.
     
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  12. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    The secret of being a good diagnostician is to find out what the owner did.

    Owner: This piece of **** blah blah blah. I'm going to sell it. (Yes, naughty motorcycle. That will teach it a lesson it will never forget)
    You: So can we go back to a time when you did not have this problem?
    Owner: Yeah, yeah, piss, moan, bitch.
    You: So did you do anything to the bike between then and when this problem first appeared?
    Owner: Nope, I never touched it. (lie)
    You: Nothing at all, you didn't wash it, change the oil, lift up the seat, tighten the chain, fill the tank with diesel, nothing?
    Owner: Oh well I did this, and I did that, and there was the other thing, but we did a good job and my mate helped me.

    Cause of problem has now been revealed.
     
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    Last edited: Feb 17, 2019
  13. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Just a thought, would be good to test a pressure release valve and see at what psi the thing opens and then hook up an oil pressure gauge to a bike. I don't own one so can't help with that.
     
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  14. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    I've just removed the oil pressure sender unit from my 3LN3 FZR250R and hooked up an oil pressure gauge just for a look.

    FZR250R cold start, with 1/2 choke (high idle), oil pressure test, need's an oil change going by the colour of the oil too,
    Oil line to the gauge wasn't bled either.

     
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  15. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    I'm guessing your neighbour might have an aneurysm if you take it to redline.
     
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  16. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Just saw this mentioned at BDK in a blurb for the 400 slipper clutch.
    "One of the quickest ways to kill an FZR400 is to over-rev the machine.
    Due to the oil pressure release valve only being a couple of psi higher than is needed to get the oil into the crank at the redline and subsequently lubricate the inner main bearings it is very easy to damage those bearings."
    https://bdkraceeng.co.uk/tc/products.php?357&cPath=77

    Nothing proven for the 250 but where there is smoke there is fire and all that. I think if I wanted to race a Fizzer a few tests would be in order first.



     
  17. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    The FZR hit the limiter/redline in 1st and 2nd every run I did at that last drag meeting .... and Ive done it many a time in the years beforehand ..... time will tell maybe .... or maybe the magic Delo400 is doing an exceptional job :cool:
     
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  18. ruckusman

    ruckusman Well-Known Member Premium Member Dirty Wheel Club

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    FWIW I have read somewhere, that I have been unable to relocate since I read it, it was FZR400 related, they put a washer to increase the pressure on the spring in the pressure release valve for that very purpose.
     
  19. jmw76

    jmw76 Well-Known Member

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    Its not so much about pressure but more about flow.
    Typically on a race engine you would run with bearing clearances on the larger side of spec.
    Then you want to make sure your oil pump is in good shape or upgraded to provide plenty of flow.
    Flow is important to ensure good lubrication and cooling.
    When I have worked on GSXR oil cooled motors I have increased the pumping capability of the system.
    Check to see if later models or bigger engined siblings have an uprated pump that could simply be dropped in.
     
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  20. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    Pressure is resistance to flow, so oil flow is critical. Excessive pressure could be described a s a lack of flow, or restriction/blockage in the oiling system. It's critical to run the specified oil viscosity, too thick will create flow problems, too thin and you will get accelerated wear. Assuming oil pump and lubrication systems are OK.
     
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