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Help 3LN1 1HX ENGINE Problems!

Discussion in 'Yamaha 250cc In-Line 4's' started by ROVER LARRAGUIBEL, Jul 23, 2021.

  1. ROVER LARRAGUIBEL

    ROVER LARRAGUIBEL Active Member

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    Hi friends.

    This piece of aluminum was broken where the input shaft bearing guide goes.



    Is it possible to weld?
    or
    Change the whole block?

    Which is the best option?

    Thank you!

    5B2818E2-12BE-45D8-93FB-E16C6C1B1F0A.jpeg
     
  2. thebeefsalad

    thebeefsalad Well-Known Member

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    I can't say for certain as I don't know that engine, but Honda has a similar piece in their MC14E power plants. My best guess from your picture is it's used to locate the bearing properly in the cases. Check parts fische/service manual to be sure if nobody here answers.
     
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  3. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Can u specify which engine or bike?
     
  4. ROVER LARRAGUIBEL

    ROVER LARRAGUIBEL Active Member

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    FZR 250 (3LN1)
    1HX ENGINE
     
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  5. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    3ln1 engine.png
     
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  6. ROVER LARRAGUIBEL

    ROVER LARRAGUIBEL Active Member

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    That’s right… i have the workshop manual.

    the question is…can the broken piece of aluminum be soldered or glued?
    This question is due to the fact that the bearing of the input shaft at this moment is without the guide of the aluminum block…

    Can the engine work without that aluminum guide?

    (Forgive me for my bad english)
     

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  7. gregt

    gregt Well-Known Member Premium Member

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    That half-ring takes the thrust from the clutch operating mechanism. Without it, you risk having the mainshaft move over in the cases.
    What I've done on other engines is machine the case flat outside the ring groove - and screw on a steel piece to retain the half-ring. There should be enough material there to get 3 or so 4 or 5mm countersunk screws in to hold it all in place.

    Welding risks distortion on what is a fairly critical area. Epoxy combined with loctite bearing mount would hold for a while.
     
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  8. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Forget glue.
    possible solutions:
    1/ Pin the bearing to locate it instead of using a ring. This was popular with two stroke gearboxes. The bearing is a 6204N (the N being the groove for the snap ring). I am sure that a 6204 is used on two stroke gearboxes, so you can just buy an OEM bearing which will have the hole. Drill the small locating hole in the case and fit the correct size locating pin. Note that the standard bearing is not a C3 but some of the two stroke bearings are.
    2/ Is there a recess in the top half of the crankcase or can you have one machined? If so then move then you can probably use a full circle original snap ring
    3/ Welding will cause a lot of distortion and will require post machining of course. Welding with low temp rod is definitely worth considering IMHO. Still need to be machined afterwards.
     
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    Last edited: Jul 23, 2021
  9. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Greg's solution is a good idea too. Didn't think of that one.
     
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  10. gregt

    gregt Well-Known Member Premium Member

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    Developed on vertically split cases where the bearing retaining circlip has been hammered out of the case cos the bearing won't come off the crank....If I get one that won't budge now, I take the bearing apart. Much less damage.

    At present, with supply lines in trouble, which method he uses may depend on what he can get to hand.
     
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  11. ROVER LARRAGUIBEL

    ROVER LARRAGUIBEL Active Member

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    Hi friends.

    Thanks for your opinions!

    I have an idea...

    I have two 1HX engines (3ln1) and I would like to replace the damaged crankcase with another crankcase that is in good condition.

    It would be a good idea?
    I need new plane bearing?
    Or can the ones already used by the crankshaft be used?

    image0.jpeg
    20845D22-7551-458B-83CB-E05B7D002815.JPG
    IMG_5919.JPG
     
  12. thebeefsalad

    thebeefsalad Well-Known Member

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    odds are you will have to change bearings on the crank unless the cases match up 100% not sure how yamaha does it, but honda stamps codes on the cases, crank, and rods. match up the codes in the FSM to determine which bearings you need.
     
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  13. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Do not mix and match crankcase halves. Where possible, use a matching set of cases and the crank that came with it.

    New main bearings are a good idea. I really felt the difference when I swapped a good crank and rods into another set of cases and put new mains in. Didn't touch the rods as they were okay. Just remember to seal the crankcase halves with the correct stuff. I didn't and it leaked, a lot.

    Can I ask what led you to pull apart the engine? Was there a big problem?
     
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  14. ROVER LARRAGUIBEL

    ROVER LARRAGUIBEL Active Member

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    Apparently yamaha doesn't make new main bearings ...
    There are only Chinese alternatives on aliexpress that don't give me much security ...

    With what material seal the crankcase halves?

    Disassemble the motor because the gearbox mainshaft bearing derailed and a piece of aluminum that supports the bearing race broke.

    I still haven't come to the conclusion what caused the bearing to derail ...
     
  15. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    The AHL brand on Aliexpress make good products in my experience, I;ve used their main bearings, pistons, rings, and wristpins without issue. I would avoid gaskets from aliexpress though, particularly head/base gaskets as they are made poorly and often don't fit.
     
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  16. Murdo

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

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    Possibly a 'missed shift' where the selectors try to engage two gears at once.
     
  17. ROVER LARRAGUIBEL

    ROVER LARRAGUIBEL Active Member

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    Hi friend.

    I tig welded the broken part of the gearbox input shaft bearing in aluminum…

    I hope everything done in the engine turns out ...



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