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Help Restricted FZR250

Discussion in 'Yamaha 250cc In-Line 4's' started by Willrcr15, Oct 4, 2019.

  1. Willrcr15

    Willrcr15 Well-Known Member Premium Member

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    What's done to de restrict it ? I've a fresh re built FZR 3LN & she does a lap & comes back in saying it won't go & little else feedback other than maybe it was seizing but it's not that, then it dawned on me it'll be restricted. I have other ECU's I can try but is it more than that or maybe it's just cut a wire that reads the ignition pulse of the RPM. Thought I read somewhere there was a link in the speedo related to a restriction. Busting to get her going & see what a fresh engine pulls like, we currently run another one that goes so well.
     
  2. kiffsta

    kiffsta Administrator Staff Member Dirty Wheel Club Contributing Member

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    What year is yours ? Jap law changed in 1994 which restricted the power output to 40hp, Honda changed the cylinder head and cdi to reduce their power output, Kawasaki changes were in the cdi. Most restrictions were in the speed limiter so that you couldn’t go over 180kms per hour
     
  3. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    The only restrictions besides the 180km/h speed restrictor in an FZR250 is the valve spring's and cams.
    You probably have carby issues
     
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  4. Amara

    Amara Member Premium Member

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    Make sure that you have the right CDI box for your bike. You could have one for the later lower revving version of the 3ln engine like the one in the Zeal
     
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  5. Willrcr15

    Willrcr15 Well-Known Member Premium Member

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    Thanks all, i'll check the box, now i'm wondering if the exhaust valve isn't opening. Carbies are perfect but anythings possible,
     
  6. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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  7. Willrcr15

    Willrcr15 Well-Known Member Premium Member

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    That's a good link, i'm sure it's not that, also it's a 240 speedo.
    Carbies are perfect & better than new, i have 3 sets, tried em all.
    The more I think about it the more i'm thinking the exhaust valve, already had it apart but maybe a cable snapped or the servo's playing up or something sent to test me again. Be bloody beautiful if they just started making them again, i'd buy a new one tomorrow !
     
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  8. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    EXUP should be easy to diagnose, it cycles with the ignition, pull the left rear fairing off and watch the servo motor to see if it's working... should be able to pinch the free play out of the cables on both ends... check the exhaust side too.

    Disconnect the cables and manually operate the exhaust valve. It can also be removed for service and cleaning.
     
  9. Amara

    Amara Member Premium Member

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    Doesn't the rev gauge double as a fault code reader ? e.g. 7,000rpm = bad fuel pump ? Or am I thinking of a different bike ?
     
  10. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    Not on these... early fuel injected bikes, yes.
     
  11. Laceysnr

    Laceysnr Member Premium Member

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    Related: I was wondering just yesterday how the Across was restricted? It's a lower power output AFAIK, not a speed limit, but haven't seen anything around the intake during my work on the bike. Anybody know?
     
  12. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    The across is a heavier bike and only has two twin-throated carbs. More touring oriented. All grey import jap bikes of this era will have a 180km/h speedo restrictor circuit. Later 40hp bikes are generally built to that power via heads and cams, sometimes ignition timing and carb jets.

    Really the 250's are built to 45hp and 40hp, to get more out of them you have to spend big and do a lot of work, then you start blowing clutches and transmissions without modifications... focus on finding and fixing the problem.

    If the EXUP is stuck or not fully open, that will be a problem at full tilt.

    If it has no power I would start with checking that it is getting adequate fuel... a blocked breather on the tank can do this, as can a blocked filter, or a kinked fuel line... work your way down the system you are diagnosing.

    The only real common issue on the FZR's is the emulsion tubes and needles wearing badly. They will run pig rich, bog, and consume 5L V8 amounts of fuel. Turning the fuel off temporarily can help to diagnose this. Generally with this problem they are OK at high revs and terrible everywhere else.
     
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    Last edited: Oct 8, 2019
  13. Laceysnr

    Laceysnr Member Premium Member

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    Yeah I don't need more out of the Across, was just curious if it was easy to get the restricted later models back up to 45.
     
  14. Amara

    Amara Member Premium Member

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    Fairly sure this is for the FZR
     

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  15. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    FZR250's don't have a TPS, speed sensor (gearbox driven speedo) or tip over sensor.

    Those codes apply to some early fuel injected Yamahas, and some late carb Yamahas like my R6, which has a TPS on the carbs, a gearbox driven speedo, but no EXUP. Has a 4-2-1 exhaust instead.

    Each manufacturer will have a different built in diagnostic.

    Modern bikes are all OBD2 standard and can be read with a code reader and the right cable.

    It's not common for carbed bikes to have anything like that, generally the only electrics they have are ignition system and lights/instruments.
     
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  16. ruckusman

    ruckusman Well-Known Member Premium Member Dirty Wheel Club

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    Keyster kits through the carbs?

    If so stay tuned whilst I find the relevant posts for you - I think I know what the problem may be
     
  17. ruckusman

    ruckusman Well-Known Member Premium Member Dirty Wheel Club

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    First post located

    https://www.2fiftycc.com/index.php?threads/the-second-fizzer.9044/page-15#post-108129

    @my67xr - original discovery
    https://www.2fiftycc.com/index.php?threads/fzr250r-3ln3-bdst28-carburetors.9643/#post-105292

    Second thread - note; if at some stage because you have several sets of carbs, different components - emulsion tubes N625 VS N638 etc need the corresponding air jets, main jets differ and so on - all 5CT7 needles with shims below centre carb pair of or a combination of 5CT7 - outer pair and 5CT9 - inner pair all on the same clip setting and no shims underneath any of the needles

    https://www.2fiftycc.com/index.php?...ne-behind-block-head.10478/page-4#post-123212

    This thread covers the differences in the needle(s) - it's a PITA, but as @my67xr & @Joker discovered - minute differences/errors produce big consequences where the carbs are concerned

    https://www.2fiftycc.com/index.php?...8-26mm-carb-settings-specs-3ln-3yx-zeal.9787/

    How much do we all love Fizzer carbs - let's have a show of hands shall we...
     
  18. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

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    :D

    middle-finger-middle-finger-hand-png.png
     
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  19. ruckusman

    ruckusman Well-Known Member Premium Member Dirty Wheel Club

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    OOH Lah dee dah - Mr Fuel injection is showing off now - which makes me wish that if microsquirt units were a little cheaper I'd have a go at fuel injecting a fizzer, but alas they're not so I won't
     
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  20. Grasshopper

    Grasshopper Well-Known Member Premium Member Dirty Wheel Club

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    Yeah, we love Fizzer carbs!!!

    fzrcarb01.JPG

    Got the LiteTek kit ready :thumb_ups:

    LitekFZR1.JPG
     
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    Last edited by a moderator: Oct 11, 2019

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