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Discussion Fzr 250 problem

Discussion in 'Your 250cc Projects' started by Forky, Oct 27, 2018.

  1. Forky

    Forky Active Member

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    I’ve just done an engine swap on my 3ln1. Seems like a tight strong motor when running. I’ve chucked the carbs that I had on the old motor than ran perfectly on it and haven’t touched the standard recommended settings and isn’t receiving fuel. Fuel levels are all the same, float heights are all correct, jets, needles are all correct etc.. only runs once I’ve poured fuel down the carbs. Will also bog and die after a while. And a **** idle. The only thing I have done is changed the air mixture screws and still the same thing.

    It has 1hx over the motor and an internal oil filter so it is a 3ln motor. Identical to the one I just pulled out.

    Please help me again. This has me stumped..


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  2. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    No split's in the inlet manifold's ?
    Sound's like fuel level's are too high maybe ?
    Could drain the bowl's and the refill them and check the level's again
     
  3. Forky

    Forky Active Member

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    No splits anywhere..

    So if the fuel levels are too high, what should I set the float height at? I’ve set them all at 16mm measuring from the case to the top of the float.


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  4. Forky

    Forky Active Member

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    I’ve drained the bowls a few times and no difference btw


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  5. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    How are the needles and emulsion tubes? If they have any visible wear they will need to be replaced.

    When it starts bogging, try turning the fuel tap off, if it clears then you know the problem is fuel related.
     
  6. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    It has got the 3LN1 carby's ? if so 16mm float height is correct
    Have you checked that the needle and seat's are shutting off properly ?
     
  7. Forky

    Forky Active Member

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    The carbies worked perfect on the other motor, so since installing the new one yesterday, it’s not running right. I have the original carbies too. I’ve pulled apart and there aren’t any hectic wear for it to not work as it did previously


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  8. Tigger996

    Tigger996 Active Member

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    My Bike:
    Yamaha-Fzr250-3LN-EXUP 1989. Yamaha FZR400, Ducati 998S & 996 & 900SS & ST4. Dresda Triton. Suzuki T500 road & T500 race. RS125 with Rotax 257 engine. and a couple of Ossa trials bikes in bits and a Sachs rolling chassis
    Does the fuel pump work?
     

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