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Help Help required please FZR250

Discussion in 'Yamaha 250cc In-Line 4's' started by Tigger996, Jun 25, 2018.

  1. Tigger996

    Tigger996 Active Member Premium Member Contributing Member

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    Very hot day sprinting often when I started the bike it would start but would not rev at all, the tacho starts at 3k and it did not twitch. It wouldn't tick over and had zero response to the throttle. It would sometimes be OK if I restarted it, or if I just sat near the start line (looking like a complete pratt) letting it idle with a bit of throttle. Any ideas please.
     
  2. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Which model FZR?
    My guess is the float height's are set too high, or leaking needle and seat's, or o'ring's on the seat's
     
  3. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

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    If you havnt overhauled/cleaned/rebuilt the carbys then thats your first step
     
  4. Tigger996

    Tigger996 Active Member Premium Member Contributing Member

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    They were cleaned and rebuilt by a Yamaha main dealer 24 miles ago.
     
  5. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

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    Then take it back and tell them to sort it out

    Did they give u an inventory of parts replaced and what was done ? ... tuned ? balanced? test run?
     
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  6. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    I wonder if they're set the float's at the wrong height ?

    Check the float height's /fuel level's first then, just need some clear pvc hose and put it on the barb on the bottom of the fuel bowl, then turn the ignition on and open the drain screw

    Is it a 3LN1 or 3LN3 ?

    3LN1 float's should be set so the fuel level sit's 9.2mm above the line on the fuel bowl's, Float height is 16mm

    3ln3 float's should be set so the fuel is 10.5mm above the line on the middle of the bowl's, float height is 14.7mm


    Yamaha_FZR1000_1989_BDST_FuelLevel.jpg
     
  7. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Isn't this the same problem that the recent owner fixed by cleaning out his pilot circuit, including pilot merge chamber, and dressing his ignition leads?
     
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  8. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Isn't response mainly to do with the float height's if everything else is ok, eg good / new emulsion tube's and needle's, and mixture screw set in the ballpark.
    The op had problem's starting and idling didn't he ?


    But this sound's like it's set up too rich to me.
    If the fuel level's are ok then try leaning off the mixture screw's

    This is quoted from the Factory Pro guide to tuning Mikuni CV's
    http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html

      • To get best low-end power, set float height (fuel level) so that the engine will accept full throttle, without missing or stumbling, in 2nd gear from 2.5k to 3k rpm at minimum.


      • The Fuel level height in the float bowl affects full throttle/low rpm and, also, richness or leanness at cruise/low rpm.
    • Reference: a bike that runs cleanly at small throttle openings when cold, but starts to show signs of richness as it heats up to full operating temperature, will usually be leaned out enough to be correct if the fuel level is LOWERED 1mm. Check out and RESET all: Suzuki (all), Yamaha (all) and Kawasaki (if low speed problems occur). Needless to say, FUEL LEVEL IS EXTREMELY IMPORTANT!!!
    . If there are low-end richness problems, even after lowering the fuel level much more than 1.5mm from our initial settings, check for needle wear and needle jet
     
  9. Tigger996

    Tigger996 Active Member Premium Member Contributing Member

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    When it ran it was doing high 14 second quarter mile, no smoke screamed like a banshee so I would think the mixture is ok.
    Dealer who did the work is closed on Mondays so will check with them tomorrow. How do I "Dress the ignition leads"? I would replace them but they are molded to the coils. Could the high temperature be a factor (high for England but probably sub zero for all you Aussies).
     
  10. Tigger996

    Tigger996 Active Member Premium Member Contributing Member

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  11. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    To dress the lead's, unscrew the cap's off the end of each lead and trim of 10mm off each lead, then screw the cap's back on firm and refit to the spark plug's
    Are all 4 exhaust's the same temperature ?
    Do you know how many turn's out the mixture screw's are set to?
     
  12. Tigger996

    Tigger996 Active Member Premium Member Contributing Member

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    I didn't check the exhaust temp. It acted like it was only running on 1 or 2 cylinders but opening the throttle did not vary the rpm at all. I took the fairing off to check the plugs and wanted to start it and disconnect plug leads to find out which cylinders were at fault. But it started up with no problems. I will dress the leads. No idea what the mixture screws are set at. I will check the plugs later.
     
  13. TonyZXR

    TonyZXR Active Member Premium Member

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    Not sure how the fzr coils are wired but with my mates zxr we noticed it would do that when getting hot and it was the positive feed wire on one coil losing voltage. It would stumble and missfire with no throttle response and when shut off would not restart.
     
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  14. Tigger996

    Tigger996 Active Member Premium Member Contributing Member

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    I will check that, but there was no misfiring just very slow gutless tickover.
     
  15. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

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    Well looks like the carbs were done properly and if it was running 100% for a time afterwards then most likely rules out anything there

    Coils/ignition will start to fail, if faulty, under heat ..... and as 1 coil runs 2 cylinders sounds like it was running on maybe only 2

    As mentioned start by trimming the leads ... u can replace the leads as they do come out of the coils but its very tricky and easy to break the holding 'clip'


    coil leads 1.JPG coil leads 2.JPG

    I see there was a broken wire at your coils ... I would be having a very close look at the other wiring in that area

    Test the coils also

    https://www.2fiftycc.com/index.php?threads/multimeter-coil-test-–-twin-lead-coils.9510/

    https://www.2fiftycc.com/index.php?threads/trim-your-spark-leads.8032/

    https://www.2fiftycc.com/index.php?...eads-spark-plug-configuration-inline-4s.8176/


    If u end up replacing the leads and/or the plug caps these guys have everything ... and they are in your part of the world :thumb_ups: ... they sell on ebay also

    http://www.gsparkplug.com/ignition

    The other thing is to check the breather in the fuel cap ..... if its blocked and your pulling large amounts of fuel running on the strip it would create a vacuum and not much fuel would flow eventually, but would probably be fine after sitting for awhile ..... when its running badly just open the fuel cap and see if it improves (not with a full tank though)

    Fuel tap can be rebuilt with new seals

    https://litetek.co/Fuel_Tank_O-Rings_Yamaha.html

    Oil level light staying on is common ... my 3LN1 goes on and off at random times .... the sender/sensor in the sump gets full off junk

    oil level sendor.jpg
     
  16. Tigger996

    Tigger996 Active Member Premium Member Contributing Member

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    I will test the coils etc. I did try it with the fuel cap open (it was a problem I have had with an MG and a Ducati) so it's not that. I dropped the sump and cleaned everything I could see after having the carbs sorted, I had to make an alloy gasket/anti surge plate as the originals are not available. Thanks
     
  17. Tigger996

    Tigger996 Active Member Premium Member Contributing Member

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    Don't know if it is connected but as my battery (brand new) flattens in a couple of days, I disconnected the earth and then checked the voltage between the earth and the battery (ignition off). I got a just over 12 volts. So I have a problem there.
     
  18. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    How are you getting 12v if the batterys' earth wire isnt touching the frame?
    Or were you measuring across the battery postive and negative's
     
  19. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Connect the battery again and measure from the negative lead at the battery to the end where it bolts to the frame, how many volts do you get then? You could alao measure how many amps are going through the battery if you change your meter to amps and the disconnect the battery positive, put the red lead from to meter to the battery positive terminal and the negative meter lead to the positive battery lead.
    The unplug all the connections and see what is drawing power with the ignition off. Might be a corroded switch thats stuck on somewhere ?
     
  20. Tigger996

    Tigger996 Active Member Premium Member Contributing Member

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    I disconnected the earth cable, then measured between the earth cable and the -ve battery terminal.
     

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