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Project My FZR250 3LN6

Discussion in 'Your 250cc Projects' started by driftwood, May 10, 2020.

  1. neoncrypnid

    neoncrypnid Member Premium Member

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    In my limited experience, i dont think the timing is adjustable. The slotted bolt is just a cover to inspect the flywheel and timing marks. The actual top dead centre mark is on the side of the flywheel, to see it you gotta take the whole cover off. I made the mistake confusing the two doing the valve clearances.
    Are the spark leads attached to the right plugs?
     
  2. driftwood

    driftwood Member

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    Ahhh, correct - it's just a screw-in plug. Leads were labelled. Clearances were fine BTW (28k on the clock)
     
  3. neoncrypnid

    neoncrypnid Member Premium Member

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    Does it try to start at all? Any spluttering or sounds like its trying to run?
    Maybe double check exhaust isnt blocked anywhere? Wasp nest or something will stop anything running
     
  4. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Have you checked the float height's/fuel level's ?
    How many turn's out are your mixture screw's ?
    Is the choke on full?
    If the engine is firing, you should be able to feel a slightly warm exhaust pipe up near the head


    The timing mark's are inside the engine case around the flywheel, take the stator cover/stator off the engine on the r/h side
    Picture courtesy of @Linkin

    [​IMG]

    Timing mark's on the end of the cam's should also be lined up close to the dot's on the rail's, that's if the engine is on TDC for cylinder 1 on the compression stroke

    [​IMG]
     
    Last edited: Aug 7, 2020
  5. driftwood

    driftwood Member

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    Ahhh, coupla coughs when the exhaust is removed. Strange, can pump air thru easily.
    Going back to take idle screws from 2 to 3 turns out.
     
  6. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    OK - just putting this out there, have you had the cams out to do valve clearances?

    If not, do you know if perhaps they'd been out previously to do same.

    We had someone here who was given a non-runner, same issue, similar symptoms - popping, but not running - turns out that when head had been done by P.O., cams went back into wrong positions Exhaust <-> Intake swapped - no damage done

    From memory IN & EX is cast on the cam between cylinders 1 & 2

    You can do a quick visual check, TDC - cylinder 1 firing should have those cam lobes for cylinder 1 pointing outwards - i.e exhaust cam lobes going to turn onto the buckets and the intake lobe a long way from rotating onto the buckets
     
  7. driftwood

    driftwood Member

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  8. driftwood

    driftwood Member

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    It had pretty black CR9EK dual sparks, tried CR8E and getting better - but still have a prob of running on 3cyls. Either 1 or 4, or both, are cold. Trimmed lead ends, measured resistance end-end of 33kOhm (which is same as 2&3).
    Thinking of putting in a couple hotter - any advice re CR7E, or CR7EB, or CR7EH-9 (shorterthread)?
     
  9. driftwood

    driftwood Member

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    oops, skip the CR7EB idea (solid connector)
     
  10. driftwood

    driftwood Member

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    Plug had gap of 0.7, tried 0.8mm ... same. Nice white spark.
    But it's wet when I pull it out.
     
  11. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Could be something to do with the mixture screw's being 3 turn's out
     
  12. DannoXYZ

    DannoXYZ Active Member

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    Measure mains, I’ve seen many, many cases where jets were drilled put by POs thinking that would give them more power.
     
  13. DannoXYZ

    DannoXYZ Active Member

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    “drilled out”
     
  14. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    You can edit your threads @DannoXYZ . I have to do it all the time because I am not politically correct :)
     
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  15. driftwood

    driftwood Member

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    I'm getting more & more confused. Euthanasia is looking good.
    The float can sit at 3 positions: the backstop (pictured), just touching the needle, and with spring compresses(sealed off). What height do I set a 3LN6 pls??? 18mm shown (excuse the camera parallax error), then rotate the body off the mounted position and get 12mm as it rests on the valve spring IMG_20200904_195606_977.jpg IMG_20200904_195606_977.jpg IMG_20200904_195606_977.jpg
     
  16. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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  17. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    IIRC, @my67xr and I nailed it down to exactly 14.7mm float height, well that's what he's checked and measured it at for best performance on his 3LN3, the fuel height is 10.5mm

    WHOOPS should actually answer the question, it's measures with the float just touching the spring and not compressing it
     
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  18. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Yeah 14.7mm is perfect in my 3LN3, same height as 3LN5, 3LN6 and 3LN7
    So where your's measure's 18mm, it should be 14.7mm with the float tab just touching the pin in the end of the needle (needle and seat)
     
  19. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    This is the 'tool' i made for setting my float's, i used a piece of icecream container lid,
    With the float sitting at this angle, the float tab is only just touching the tip of the needle

    [​IMG]
     
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  20. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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