Help Does anyone have a 3LN C-stamped conrod for sale?

Discussion in 'Yamaha 250cc In-Line 4's' started by Xavier492, Aug 18, 2018.

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  1. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Have you got photos? I'd be very interested to see what yours look like and compare to the ones that I used
     
    Linkin, Aug 19, 2018
    #21
  2. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    Yours was good info as well @maelstrom so many combinations of rod length / Piston and then the need to take into account piston speed, volumetric efficiency of the inlet and outlet systems to be able to cope with the volume of air that the engine can utilise.. I love all that stuff :)
     
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    Andych, Aug 19, 2018
    #22
  3. Xavier492

    Xavier492 Member Premium Member Contributing Member

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    20180803_170422.jpg 20180801_200054.jpg 20180803_170432.jpg
     
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    Xavier492, Aug 19, 2018
    #23
  4. Xavier492

    Xavier492 Member Premium Member Contributing Member

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    I went to my usual workshop for the FZR (which seems to be the only place open on Sunday) and while they had 2 FZR250s in there, they had no conrods or records of where to get them.

    Either I could buy another 3LN engine ($550) or try my luck with the eBay conrod.

    I am moving house next weekend so there will be no more garage to work on the FZR and I will have to sell one of the bikes.

    20180819_140707.jpg
     
    Xavier492, Aug 19, 2018
    #24
  5. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    That's unfortunate that it chipped like that. Looks different to the other piston by my eye.

    Are they oversize? The bottom of the bores should have a lip to assist with installation.
     
    Linkin, Aug 19, 2018
    #25
  6. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    I should have some 3LN conrods possibly later today
     
    GreyImport, Aug 19, 2018
    #26
  7. Xavier492

    Xavier492 Member Premium Member Contributing Member

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    The engine rebuilders said my engine looked good and said it's not honed out enough for oversize. I noticed the lip on the bores, but I suspect that may have been what caused the oil ring to move and be bent out.

    Also the top picture is the original piston. You can see the weight difference between OEM and imitation.
     
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    Xavier492, Aug 19, 2018
    #27
  8. Xavier492

    Xavier492 Member Premium Member Contributing Member

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    Any that you can fastmail to NZ?
     
    Xavier492, Aug 19, 2018
    #28
  9. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    It isnt exactly a lip on the bottom of the bore.. it is a taper to allow the rings an easy entry when installing the barrel over the pistons.
    If they were new rings... did you check the end gaps?
    The best method is as @Linkin mentioned before.. but dont have the middle pistons at TDC.. and support the barrels either end so you dont drop them.. or have someone to help you..
    They are not the easiest motor to reassemble but well within most peoples skill level.
    Are you doing it with the engine in the frame or on a bench?
     
    Andych, Aug 19, 2018
    #29
  10. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Only found 1 ... and its :oops:


    IMGP1676 (Medium).jpeg IMGP1679 (Medium).jpeg IMGP1677 (Medium).jpeg IMGP1678 (Medium).jpeg
     
    GreyImport, Aug 19, 2018
    #30
  11. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

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    Close and hone and that would be fine.
     
    Murdo, Aug 19, 2018
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  12. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    So long as the cap is the right one for the conrod.. then I agree with the Good Dr @Murdo
     
    Andych, Aug 19, 2018
    #32
  13. Xavier492

    Xavier492 Member Premium Member Contributing Member

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    @GreyImport How much would you let that go for? I still have the old conrod but it looks a bit toast.

    FZR3.JPG
     
    Xavier492, Aug 19, 2018
    #33
  14. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    GreyImport, Aug 19, 2018
    #34
  15. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    Wow, that has been very hot. What is the crank pin like?
     
    Andych, Aug 19, 2018
    #35
  16. Xavier492

    Xavier492 Member Premium Member Contributing Member

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    As far as my untrained eye can tell, it just needed a polish. If you spot something fatal then I'll just buy a new engine.

    20180722_174442.jpg
     
    Xavier492, Aug 20, 2018
    #36
  17. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    Is that pic after you have polished it?
    You will need to measure it and also make sure that there isn’t wear on the sides. You don’t want excessive sideways movement.
    Not much you can do until you get the other Rod from @GreyImport as you won’t get accurate info from the heat affected unit.

    Just remember that these things rev to 18000 plus so big ends etc need to pretty good otherwise the end result can be nasty and dangerous.


    Sent from my iPhone using Tapatalk Pro
     
    Andych, Aug 20, 2018
    #37
  18. Xavier492

    Xavier492 Member Premium Member Contributing Member

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    That was right after I removed the burnt rod.
    I took the vernier caliper to it and there was almost no difference from the next pin.
    I made sure to order new bearings - take a look at the attached photos.


    FZR7.JPG FZR4.JPG
     
    Xavier492, Aug 20, 2018
    #38
  19. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    Wow, I wouldn’t be using either set of those bearings.
    If you are changing all the big end bearings just make sure you know which cap goes with which conrod. They are matched sets so mixing them up will not be good.
    They should be marked, generally with a light hit from a Centre punch. 1 dot for Cylinder 1 on the cap and the rod and so forth across each one.




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    Andych, Aug 20, 2018
    #39
  20. Xavier492

    Xavier492 Member Premium Member Contributing Member

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    I'll make sure to check.
     
    Xavier492, Aug 20, 2018
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