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Project FZR400 Dragster

Discussion in 'Other Projects - Other Bikes (non 250's)' started by GreyImport, Oct 20, 2022.

  1. Murdo

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

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    Wow, they stung you on the postage considering it was only coming from Wollongong.
    I see you have resistor plugs, have you removed the resistors from the plug caps or are you resisting the resistors? :D
     
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  2. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    They are the plugs that were in it and Ill be replacing them
    So what happens if theres resistor caps on resistor plugs? .... reduced spark?

    From what I can find from other FZR400 models, NGK CR8E is standard

    This is the markings on the stock caps

    400 plug cap.jpg
     
    Last edited: Jan 17, 2023
  3. jmw76

    jmw76 Well-Known Member

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    Typically the high tension side of the ignition runs optimally with about 10k ohms of series resistance.
    This can often be made up with a mixture of resistors in the plug caps, resistor plugs and sometimes resistive plug leads. On cbrs they typically have 5k ohm resistors in the plug caps and 5k ohm resistor plugs. the plug wires are straight copper.
    You can measure each with a multimeter to see what they are. For plugs measure centre electrode to pin on the top. For plug caps measure between each end.
     
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  4. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Same as the FZR250


    CR8E are 5k

    Stock cap .... :idk:


    PXL_20230117_091230721 (Medium).jpg
     
  5. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    FWIW, just in case you've got errant plug cap resistor readings - if you look into the plug end of the cap and there's a slotted brass part, then it can be unscrewed and you'll find a resistor in there - got that far diagnosing YZF600 plug caps, I haven't located replacement resistors
     
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  6. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Yea Ive done that before with the 250 caps

    Theres no markings on the resistor but reads 9.5

    And my question would be surely Yamaha would have it correct from the factory

    Now does the little metal disc go back between the spring and the resistor? :cool:


    PXL_20230118_002256226 (Medium).jpg
     
    Last edited: Jan 18, 2023
  7. jmw76

    jmw76 Well-Known Member

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    I would expect that Yamaha had worked it out correctly.
    Secondary HT resistance on cars is often as high as 20k ohm.
    I wouldn't worry about it. If they all measure similar than you are good to go.
    If it an't broke, don't fix it.
     
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  8. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Thinking on it, I think the little metal disc should go between the spring and the resistor because it gets full circumference contact with the spring and full contact with the resistor.

    BTW, what spec does the manual give for the plug cap resistance?
    Is it 5K and that's what's got you flummoxed?
     
  9. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    That was my thinking also

    The "top" end of that spring had a little corrosion on it so Ill have to check the others

    I was just going on peoples comments :D

    The 3EN2 doesnt have a PDF manual but this I finally found from one of the other models

    cap resistance.jpg



    Carry on ... nothing to see here ..... :crazypilot:
     
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  10. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Upside, now you know for certain that it's within spec and need not be worried about again.
     
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  11. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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  12. Why?

    Why? Active Member Premium Member

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    Do the fairings from an FZR250 fit a FZR400?

    Thanks in advance
     
  13. gregt

    gregt Well-Known Member Premium Member

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    Be careful changing ignition resistances. Some years back I got caught with a customer FZR400 racebike. Needed plugs so i put in non resistor 10's. It fired twice - I heard it - and refused to fire again until resistor plugs went back in.
    We came to the conclusion the ignitor box had a diagnosis circuit built in that required a minimum resistance in that circuit to function correctly.
    Something like the FZR1000 box which has a "limp home" mode when something fails. Found out about that one at the track...
     
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  14. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    Here you go @GreyImport a quick 30 minute rebuild on an FZR400 engine :)
    They didnt even get their tee shirts oily and dirty... they just didnt try hard enough.
     
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  15. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    They cheated ... they didnt even pull the carb bank apart :lolsign:
     
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  16. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    ... and they spent so much time measuring bore clearances, mains, big ends, ring gaps, gearbox bearings, gears, selector forks, and so on ad nauseum.
     
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  17. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Old RR plug is shot .... was fused in place and well and truly stuck

    PXL_20231006_034135377.jpg

    PXL_20231006_034941298.jpg
     
  18. gregt

    gregt Well-Known Member Premium Member

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    If it's track only use, you can run it total loss to save some HP. Most of the 400's raced here in our early F3 were running total loss ignitions. That carries through to alternator rotor cutting back to leave the ignition triggering lump(s) on a narrow rotor.
    Starter motor, starter clutch removal is also weight saving - but leaving the starter on is convenient for the (cough) older competitor.
     
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    Last edited: Oct 6, 2023
  19. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Took a punt on another models carb boots as mine are unobtainium .... all the way from the US of A

    Close but no cigar
    Ill have to contact Dodgy Bros Inc and get some advice when its airbox fitment time :cool:


    PXL_20231114_034712644.jpg


    PXL_20231114_034735869.jpg
     
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  20. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Hopefully they run as good as they now look :D


    carbs before.jpg

    carb rebuild.jpg


    carb clean 2.jpg

    carb clean 1.jpg
     
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