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Project FZR250 2KR 3HX1 resto-1project

Discussion in 'Your 250cc Projects' started by BlackBladeDesign, Aug 2, 2018.

  1. Murdo

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

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    Is the EXUP valve working? If this is not working correctly it could be your 10K problem.
    You've done a great job so far, looks good.
     
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  2. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    The mixture screw has input from idle to wot
    Is the mixture screw set at the factory setting, or have you warmed up the bike to normal operating temp and tuned them ?
    Could be something like the carb sync and mixture screw setting's.


    effects3.gif


    As @Murdo mentioned could be the EXUP not opening fully, but if it goes ok to 10,000 rpm then i reckon it must be close and still in the ballpark.
    Maybe just check the holes line up, and that the cable's are not too tight.
     
  3. BlackBladeDesign

    BlackBladeDesign Consistently Inconsistent Premium Member

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    It seems like the exup valve is opening up, the servo definitely works and there's and audible difference between open and closed when I rev it up.

    By mixture screw do you mean the pilot screw(on the bottom, and on the diagram side, the small flathead screws?)? I set that to 3 turns out for each one. It's really easy to start, but I can only start it wide open and *without* the choke on. It idles easily immediately after I start it though.
    So 3 turns out is too much, should I go 2 1/2 or 2 3/4
    I don't know which screw to adjust while the bike is running besides this one.

    IMAG0066-2.jpg

    The problem with the bracket I made for the exup cables is that the cables are held in to the chrome cover. So I can't really take it off to see if it opens fully because they won't be held in place. They are the proper cables though and they are in good nic'
    I couldn't find the original bracket anywhere besides one for a fzr1000 that looks similar to the one in the diagram but I didn't want to see hundreds on that part that might not work.

    One more thing, how are the cables routed originally? Do they take the same path as the battery & coolant overflow pipes past the suspension? If anyone could post a pic of their one itd help alot cause I'm really not sure
     
    Last edited: Nov 9, 2018 at 9:12 AM
  4. ruckusman

    ruckusman Well-Known Member Premium Member Dirty Wheel Club

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    I'm searching for the thread which had another cause for the problem of not revving in gear, which was the jets being in the wrong locations if memory serves - we prompted the OP to go back and re-check past work which located the cause.

    I'll post that thread if I can locate it

    In the meantime there is this one as a possible cause/solution.

    https://2fiftycc.com/index.php?threads/fzr-2kr-wont-rev-over-10000-when-in-gear.3500/

    Edit

    OK found it, this was from fitting Keyster kits with the main jets in the incorrect boxes for inner and outer carbs - it is definitely worth double checking if you've disassembled & cleaned the carbs

    Note that smaller the main jets go in the inside carbs, larger main jets go in the outside carbs

    https://2fiftycc.com/index.php?threads/fzr250-3ln3-carb-problem.8770/page-3#post-111942
     
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    Last edited: Nov 9, 2018 at 10:10 AM
  5. BlackBladeDesign

    BlackBladeDesign Consistently Inconsistent Premium Member

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    I cleaned out each one individually before putting each back in, and I haven't put any kits in. Though I don't know any history of these carbs so it's possible that they're incorrect. Thanks for the info
     
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  6. ruckusman

    ruckusman Well-Known Member Premium Member Dirty Wheel Club

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    Yes welcome to the world of dealing with the quirks and intricacies of previous owners - troubleshooting can be difficult when there are errors which can present ambiguous symptoms
     
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  7. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

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    Check also that the main jets arnt mixed up with the starter jets

    Jets.jpg
     
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  8. BlackBladeDesign

    BlackBladeDesign Consistently Inconsistent Premium Member

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    Thanks again guys, I'll pull it apart later tonight and upload some pics
     
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  9. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

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    Heres the carb specs from the 2KR manual

    Main jets are all #72.5
    Starter jet #15?
    Float height 17.5-19.5mm ?
    Needle clip at #3 slot ?


    2kr carbs.png
     
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  10. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    You can just see the EXUP cable's running down between the starter and the clutch pivot arm in this pic

    Inkedp6_LI.jpg

    The 3HX1 carb's are slightly different to the 2KR carb's, like the difference between 3LN1 and 3LN3 carb's with the jetting

    https://en.impex-jp.com/catalogs/moto/yamaha-2/fzr250/fzr250-3hx1-010-1988-3846/carburetor-134561.html

    Air jet is a #140 (small one in carburetor intake throat)
    Main jet is a #72.5
    Pilot is a #17.5
    And no starter jet's, they just have a pick up tube


    I would be putting the mixture screw's (Pilot screws) back to 2.5 turn's out and see what it does,
    i've found the FZR's need choke to start when cold when the engine is running the best.

    6e5797c7af8f7e1753b910f61d40db47.png


    The fuel level's in the carb's should be 17.5mm below the marking on the side of the carb,
    This mean's the float height's should be set at 10.5mm off the base of the carby

    2kr carbs.jpg
     
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    Last edited: Nov 9, 2018 at 2:45 PM
  11. ruckusman

    ruckusman Well-Known Member Premium Member Dirty Wheel Club

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    That's good info right there, so obviously the main jets being the same across all 4 - the wrong inner and outer carbs jets isn't a possibility

    Like @GreyImport suggests checking - I did seem to recall someone else having mains and starters mixed up with a similar symptom because up to ~10K it was needle and tube governing fuel flow, then it progressed onto the main jet and stumbled
     
  12. BlackBladeDesign

    BlackBladeDesign Consistently Inconsistent Premium Member

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    Put the pilot screw to 2.5 turns out. It's running the same but I haven't had a chance to ride it outside yet. The rectifier was running hot again today too so I'm pulling the rectifier connector apart to replace the wires and tabs. Can anyone tell me where the three wires from the stator goes on each pin(wires fell apart after I removed the tape)

    I know the red wire goes to the bottom right of the rectifier, but don't know where any of the three stator wires go. Eg.where does the horizontal pin and either vertical one go(assuming the red in this case is bottom right, and the pin above the red is upper right) 15418149682169169164384790776578.jpg 15418150243926646347378061966312.jpg
     
  13. ruckusman

    ruckusman Well-Known Member Premium Member Dirty Wheel Club

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    If I've understood your query correctly, the stator is 3 phase alternating current - what does that mean, it means it doesn't matter which order they are connected in

    So if there's a 4 pin connector to the Reg/Rect and you know which one is the positive DC output, the other three are for the stator in no particular order, which also means that the earth is through the case and needs to be as clean as possible for good performance
     
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  14. BlackBladeDesign

    BlackBladeDesign Consistently Inconsistent Premium Member

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    Thanks for that man, I've cleaned up the mounting point with some sandpaper and a wire brush. The bike frame was painted at one point by the previous owner but the guy didnt cover the rectifier mounting bracket.
     
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  15. BlackBladeDesign

    BlackBladeDesign Consistently Inconsistent Premium Member

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    No more light flicker. Win!
    And the rectifier has some normal operating heat now, but nothing as ridiculous as before.

    Also when I first press the killswitch, the servo rotates, and I've confirmed that the exup valve does too. *but* it doesn't rotate when the bike as actually running, or when I twist the throttle, it just stays closed. If I turn the key off when the servo is "calibrating" in the open position, then disconnect the servo the bike runs alot better, haven't tried for redline yet but I got it to about 14k

    Edit:
    Is it normal for the fan not to come on till the red?
     
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  16. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Fan should come on at 85 degree's C
    Try topping up your water, best off doing it when the bike has been running for a little while (radiator cap off)
    Make sure the bike is upright too, maybe rock it side to side to help get rid of any air pocket's while topping it up

    I reckon you might need to hold the rev's for a bit for the EXUP to open.
    Mine only slightly move's if i blip it.
     
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  17. BlackBladeDesign

    BlackBladeDesign Consistently Inconsistent Premium Member

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    Up
    I filled it up with coolant when I put actual Orings on the coolant pipe(rather than that sillicone "repair" I did a while back)
    It took a while to get all the air out but it's all bled(?). Wouldn't really be a good fix but I could just make the fan be permanently on.

    The exup valve opens ever do slightly but not enough when I'm riding. Took it for a spin today and it goes to redline but only when the valve is kept open by disconnecting the servo at the right moment.
     
  18. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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  19. BlackBladeDesign

    BlackBladeDesign Consistently Inconsistent Premium Member

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    *ignore the polishing compound for the first pic*
    Started cleaning up the muffler, drilling out old pop rivets and replacing them with new ones. Still gotta sand out the scratches somehow but it looks alot better with all the rivets cleaned up.
    IMAG0206~2.jpg IMAG0246~2.jpg IMAG0245.jpg
     
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  20. BlackBladeDesign

    BlackBladeDesign Consistently Inconsistent Premium Member

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    Front indicators.
    Once the fairing kit arrives I think she's good for a roadworthy(need the windscreen and can't have cracked front cowl)
     

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