1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Help FZR 250r 3LN1 rev issues

Discussion in 'Yamaha 250cc In-Line 4's' started by Spen, Mar 15, 2020.

  1. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

    Messages:
    4,313
    Likes Received:
    2,383
    Trophy Points:
    898
    Joined:
    Jun 18, 2016
    Gender:
    Male
    Occupation:
    Panel Beater, Spray Painter, Custom Fabricator
    Location:
    Adelaide, South Australia
    My Bike:
    Yamaha's , 1990 FZR250R 3LN3 , 1986 XT250TS 57R , 1984 IT200L 43G, 1976 IT400C 510
    To open the TCI use a small flat head screwdriver and gently press in the tab's as you pry it apart

    tci repair.jpg
     
    • Like Like x 1
    • Informative Informative x 1
  2. Spen

    Spen Member

    Messages:
    11
    Likes Received:
    0
    Trophy Points:
    5
    Joined:
    Jan 21, 2020
    Gender:
    Male
    Location:
    Plymouth
    My Bike:
    Fzr 250
    My tci isn't like that, it's got loads of clip connections rather than those insert holes and the components are in different positions, I'll take a pic today
     
  3. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

    Messages:
    4,313
    Likes Received:
    2,383
    Trophy Points:
    898
    Joined:
    Jun 18, 2016
    Gender:
    Male
    Occupation:
    Panel Beater, Spray Painter, Custom Fabricator
    Location:
    Adelaide, South Australia
    My Bike:
    Yamaha's , 1990 FZR250R 3LN3 , 1986 XT250TS 57R , 1984 IT200L 43G, 1976 IT400C 510
    Sorry forgot your's is a 3LN1,

    This style
    3LN-82305-00
    131800-5290
    [​IMG]
     
  4. Spen

    Spen Member

    Messages:
    11
    Likes Received:
    0
    Trophy Points:
    5
    Joined:
    Jan 21, 2020
    Gender:
    Male
    Location:
    Plymouth
    My Bike:
    Fzr 250
    Ok, starting to suspect float heights now, the manual say 9.2mm but where am I measuring that from, do I need a tube and attach it to the fuel bowl drain and see how hight the level is or do I need to take the bowl off and measure it with a rule?
     
  5. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

    Messages:
    4,730
    Likes Received:
    2,870
    Trophy Points:
    943
    Joined:
    Mar 18, 2014
    Location:
    Sydney NSW
    My Bike:
    FZR250R 3LN6
    The Float height setting changes the fuel level. Measure the fuel level and adjust the floats accordingly.
     
    • Agree Agree x 1
  6. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    3,225
    Likes Received:
    1,416
    Trophy Points:
    918
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    This post which has the pic and a link to the original thread with the details - 9.2mm is the fuel level which is the important measurement

    https://www.2fiftycc.com/index.php?threads/first-bike-the-fzr250-3ln.10816/page-3#post-130275

    Note, as it turns out - the float height as measured PLUS the 'fuel level' sums to 25.2mm - 25.4mm - so a float height of 16.0 - 16.2mm for the 3LN1 appropriately yields a fuel level of 9.2mm - so you can measure the float height without disassembling, measure the fuel height and then 25.4mm MINUS "fuel height" should give a good indication of the float height and vice versa

    If anything is out, then at least you know what the target measurement should be for the float height to achieve the correct fuel level
     
    • Like Like x 1
    Last edited: Mar 22, 2020
  7. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

    Messages:
    4,313
    Likes Received:
    2,383
    Trophy Points:
    898
    Joined:
    Jun 18, 2016
    Gender:
    Male
    Occupation:
    Panel Beater, Spray Painter, Custom Fabricator
    Location:
    Adelaide, South Australia
    My Bike:
    Yamaha's , 1990 FZR250R 3LN3 , 1986 XT250TS 57R , 1984 IT200L 43G, 1976 IT400C 510
    Float height for the 3LN1 is 16mm from the base of the carby to the point of the float, with the float tab only just touching the tip of the needle (needle and seat),
    this will give you a fuel level of 9.2mm above the line on the outside of the fuel bowl
     
    • Nice Work Nice Work x 1
    Last edited: Mar 22, 2020
  8. Spen

    Spen Member

    Messages:
    11
    Likes Received:
    0
    Trophy Points:
    5
    Joined:
    Jan 21, 2020
    Gender:
    Male
    Location:
    Plymouth
    My Bike:
    Fzr 250
    Can't see your image for some reason, anyone know where I can get a new one?
     
  9. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

    Messages:
    4,313
    Likes Received:
    2,383
    Trophy Points:
    898
    Joined:
    Jun 18, 2016
    Gender:
    Male
    Occupation:
    Panel Beater, Spray Painter, Custom Fabricator
    Location:
    Adelaide, South Australia
    My Bike:
    Yamaha's , 1990 FZR250R 3LN3 , 1986 XT250TS 57R , 1984 IT200L 43G, 1976 IT400C 510
    Might be able to get them from Japan if someone has some new old stock, but they are obsolete now
    Part Number is 3LN-82305-00-00

    https://www.megazip.net/zapchasti-d...trical-1-13355868#/il-314557290-789767-789767


    @kiffsta from motoREcycle has a used one on ebay atm
    It has been labelled wrong as a 3LN3, but is from a 3LN1
    https://www.ebay.com.au/itm/1994-Ya...552636?hash=item215545b5bc:g:H1QAAOSwKb1bRsVc

    [​IMG]


    These guy's can fix them
    Or supply and fit brand new internal's from $380
    http://www.carmoelectronics.com.au/index.php?main_page=index&cPath=493_4686_2129
     
    • Like Like x 1
  10. Spen

    Spen Member

    Messages:
    11
    Likes Received:
    0
    Trophy Points:
    5
    Joined:
    Jan 21, 2020
    Gender:
    Male
    Location:
    Plymouth
    My Bike:
    Fzr 250
    Okay, I'm back gentlemen
    Recently I had restarted the fzr fix, as we know the misfire problem only happens a 13000rpm and above.
    The mechanic I spoke to said they check compression which I should have done really in the first place. Turns out number 2 cylinder was at 40psi, no good, so I've replaced all 4 ring sets with new ones and there up to 110psi. The kind gentlemen before me said to replace the tci, I've gotten a second hand one from Japan and fitted it. This is all very nice but guess what? The misfire is still there, the added compression helps as it's not as strong nether the less it's still there.

    So far I've rebuilt the carbs and dynotuned them with an a/f reading.
    Replaced both coils
    New plugs and caps
    New tci
    Calibrated the exup valve
    New oil and filter
    New rings and gaskets

    I'm starting to pull my hair out with this thing!!
     
  11. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

    Messages:
    10,914
    Likes Received:
    6,709
    Trophy Points:
    1,168
    Joined:
    Jun 14, 2012
    Gender:
    Male
    Occupation:
    Between a Rock and a Hard Place
    Location:
    North by NW NSW Oztralia - Tamworth
    My Bike:
    *Kawasaki ZXR250C *Yamaha FZR250R 3LN1 *Yamaha FZR400 *Triumph Bonneville 750 T140V *Triumph Daytona 675 *Triumph Tiger 800XC
  12. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    3,225
    Likes Received:
    1,416
    Trophy Points:
    918
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    Perhaps take a look at the thread by @Mike Green and his experiences with valve float because of the installed spring lenght, at this point you've all else

    https://www.2fiftycc.com/index.php?threads/fuel-injected-turbo-fzr250-half.10957/
     
  13. Mike Green

    Mike Green Well-Known Member Premium Member

    Messages:
    177
    Likes Received:
    246
    Trophy Points:
    248
    Joined:
    May 9, 2020
    Gender:
    Male
    Occupation:
    Taking it easy
    Location:
    Auckland
    My Bike:
    Yamaha FZR250
    If the mixture is going lean it may be valve float.
    I wouldn't skip checking simple things as well like the battery voltage at the revs where the problem is happening. It may also be damaged trigger wiring. At speed the signal speed is getting up there for a plain wire pair. Not so much the frequency of the pulses, but the rise time of the pulses. I haven't run a bike and scoped the waveform but I have run a trigger disk in a mill and monitored the pickup coil output(no load).
     
    • Like Like x 1
Tags:

Share This Page