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Help ZXR250A Failure to idle. No Fuel?

Discussion in 'Kawasaki 250cc In-line 4's' started by RyanZXR, Mar 28, 2020.

  1. RyanZXR

    RyanZXR Active Member Premium Member

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    Hi,

    I have a video explaining what I've done to my bike, and showing how it's running, and not idling.

    I am pretty lost, I don't want to go ahead and replace everything because half the things on the bike have hardly 2,000 kms on them.

    Don't hesitate to reply or message me thanks,

     
  2. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Videos are never very good for hearing things. But it does not sound like 4 cylinders. Are all 4 exhausts equally hot?
     
  3. RyanZXR

    RyanZXR Active Member Premium Member

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    I agree with you there.

    They're not equally hot. 1&4 are not as hot as 2&3. I will double check tomorrow. Exhausted right now.
     
  4. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    That sounds like it could be a coil problem.
     
  5. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Or a TCI problem. 99.999999% of coil problems can be traced to plugs, leads & TCI units. IMHO
     
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  6. jmw76

    jmw76 Well-Known Member

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    The fact that you can not get it to idle makes me think an air leak or butterflies out of sync. Did you connect up all the vacuum lines to the carbs? Did you disturb the butterfly connections when you removed the carbs. Definitely doesn't sound like it is running evenly on all cylinders. I am assuming you have brand new plugs.
     
  7. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Swap the coils and see if the result is the reverse

    Get a laser temp gun ... cheap and gives u a more accurate result

    A bike running correctly ....
    cold start : choke , no throttle , starter
    hot start : no choke , no throttle , starter

    With the manual choke on it will idle high initially

    First thing I would do is fit the airbox ... with or without filter

    And put the fuel tap on 'prime' .... this bypasses the vacuum fuel tap system so fuel runs direct to the carbs

    I didnt see you use the throttle and rev the bike at all .... ?


    gun.jpg
     
  8. PilbaraGuy

    PilbaraGuy Active Member Contributing Member

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    Capture.PNG G'day Ryan.
    I am by no means an expert on these things, just learning myself at the moment as I am having problems with my own running but at the start of the video you said that you set the float levels to 15mm as it was running lean previously.
    I have recently rebuilt, cleaned & set my carbs, synced the butterflys etc & it says in the manual that float height is supposed to be 9mm (+/- 1mm). I think if you have blown your level out to 15mm that the level may be lower than is needed for pickup & possibly starving for fuel?
    The float level if lower than what it is supposed to be could be so low that the only way it does run is if the choke is on?
    Maybe someone with more knowledge on this can confirm?
     
  9. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Fuel level vs float height/level are two completely different things. Mixed message about these happen a lot on this forum.
     
  10. RyanZXR

    RyanZXR Active Member Premium Member

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    Thanks GreyImport.

    at 4:20 into the video I manually opened the throttle, you can hear.

    I've since tried starting it with the airbox on and fuel on prime. Result worsened. The bike died while choke was full on.

    I can swap the packs and pick up a temp gun, good idea.

    I haven't touched the butterfly settings.

    I'll have a look at the manual and triple check all my settings.

    If it''s dumping fuel into some of the cylinders, that's not good and means I could have faulty floats, seats, or needles. The needles mightn't be moving freely.
     
  11. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    The problem there is the o-rings in the seats for the needle valves, they perish and split allowing too much fuel into the carb and flooding the engine, no matter what condition the rubber tips on the needles are in.

    With the fuel tap on prime it will be gravity feeding and there will be nothing to stop excess fuel flooding the engine.

    As for air leaks, the carb to airbox seals are essential, as are the o-rings on the plastic t-pieces between each carb body, they also perish and split causing air leaks, leading to a flat spot between 6-8k RPM.

    On the diaphragm side of the carbs, the little brass piece in the diaphragms is apparently a restriction. I've been told that removing them makes a difference in how the bikes perform. On my ZXR, I modified the slides by drilling an extra 2.5mm hole next to the original one, it improved throttle response but if you were in too high a gear at too low a speed, the slides would start bouncing and the carburation would crash into a flaming heap. I never got to mess around removing the brass restrictors before I sold the bike.
     
  12. RyanZXR

    RyanZXR Active Member Premium Member

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    I replaced 2 of the float seats with zxr6 float seats and needles. I noticed the new seats came with rubber seal and washers but since my old float seat needles didn't have them on, I didn't put them on the new one. I should mention the hole at the bottom is smaller in the zxr6 float seat.

    Yeah that makes sense. I have those seals between carbie and airbox.

    Oh wow. interesting.

    It's also worth mentioning all my needles in the diaphram part of the carbies were n76b. Where 2&3 should be n52x right?
    My friend who has a zxr6 and owned my zxr250 before me said this won't cause my issues I am having.
     
  13. jmw76

    jmw76 Well-Known Member

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    If you think fuel level in the float bowls might be an issue (ie too high/flooding), just try turning OFF the fuel tap while the big is running. If it starts to sound healthy, before finally dying as a result of lack of fuel, then this might be worth exploring.

    Cheers
     
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  14. RyanZXR

    RyanZXR Active Member Premium Member

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    Ah that's a good idea jmw.

    I can give this a shot thanks.
     
  15. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Fuel tap is vacuum operated, so it's only 'off' when the engine is not running. If the diaphragm in the tap is split or damaged it can leak like it's on the prime (gravity feed) position. You can pull of the vacuum line and see if it has fuel in it down where it connects to the inlet manifold. If it's not leaking there then the fuel tap is not your problem.

    Only replacing two of the seat o-rings won't solve the problem if the other two are bad, it will still leak and flood the engine.

    I suggest a complete set of keyster kits and litetek seals, and a complete overhaul of the carbs, inspecting everything for possible damage or broken parts.
     
  16. TonyZXR

    TonyZXR Well-Known Member

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    Tried it for myself , makes run like absolute shite.

    Sounds to me like you're using too much choke . Should follow this as a guide when starting it. Straight from a owners manual

    [​IMG]

    Sent from my SM-N960F using Tapatalk
     
  17. RyanZXR

    RyanZXR Active Member Premium Member

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    Yeah I am going to do a complete overhaul. Will most likely get myself a litetek kit too. Something is off but i'm not quite sure and I need to know more about the machine before doing anything else.

    Thanks for that, It's revving at 5k with the choke on which is too high. Mainly because my pilots are further out than the manual recommends. But it won't idle with them set to factory specs. But the pilot screw isn't the problem. Cheers
     
  18. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    With the pilot screw's removed from the carby's, if you shine a bright led torch down the carby's bore from the cylinder head side, can you see light through the tiny hole at the bottom of the thread's where the mixture screw screw's into ?
     
  19. RyanZXR

    RyanZXR Active Member Premium Member

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    Yeah that's correct
     

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