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Help FZR250 - coolant leak in hardline behind block/head

Discussion in 'Yamaha 250cc In-Line 4's' started by skylinerd1, May 4, 2019.

  1. skylinerd1

    skylinerd1 Member Premium Member Contributing Member

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    So from my67xr's carb thread I probably need to order: K-1203YKS and K-1203YKU from keyster? Can you re-clarify what the issue you had was or do I not need to worry about it?
     
  2. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Last edited: May 15, 2019
  3. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    The needles and tubes are not available on their own.

    @maelstrom may be able to recondition your tubes.

    For the Keyster carb kits, you need to identify what body the carbs are and order the corresponding kits - 2 inners and 2 outers.

    To use 3LN6/7 spring arangement, the whole slide assembly will need to be changed. There is a special black spacer that sits under the clip, has a small protrusion which aligns into a corresponding divot in the slide, and finally there is a plug with a spring that sits in the slide above the needle. That is followed by the actual slide spring.

    [​IMG]

    Zeal spring arangement is slightly different. Just a plastic cap on the end of the spring, with an additional smaller spring to help hold the needle straight.

    [​IMG]
     
    Last edited: May 15, 2019
  4. skylinerd1

    skylinerd1 Member Premium Member Contributing Member

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    Im using these 3ln3/5's because they have the correct throttle body size at 28mm.

    I figured it would be beneficial if I could use the zeal diaphragm springs as they have the helper spring and plastic seat to stop needle wear or am I wrong on that? Seeing as I have a broken one I figured that was the easiest solution??

    Im not sure if your following me or not here. Earlier in the thread we discovered the bike had zeal carbs on it which have the different diaphragm spring arrangement as you have pictured above. My question is can I substitute the zeal springs into at 3ln3 carb without creating other issues for myself?
     
  5. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    The emulsion tube spinning as you are trying to undo the nut, i'm pretty sure there is a pin pressed into the side of the jet holders' tube where the emulsion tube sit's?
    Try pushing the pin in and slowly turn the nut to undo it, you should feel a spot where the pin can go in deeper into the emulsion tube slot, then the nut should come loose

    As Linkin said the slide's are different in the other carby's
     
  6. skylinerd1

    skylinerd1 Member Premium Member Contributing Member

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    Ahh I see I understand so zeal springs cannot be interchanged into the early carbs because the black slides are different.... BUT are you guys saying if I swap the complete slide, diagphragm, spring it will work? And just stay with the 3ln3 emulsion tube? That makes sense to me...

    So I either need to do the above or I need to obtain a new 3ln3 spring set is that just a case of ordering from yamaha part numbers or is this an aftermarket thing or they dont exist?
     
    Last edited: May 15, 2019
  7. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    The diaphragm springs themselves should be swappable, just change them as a set.

    However if you have a set of good 3LN6/7 slides/springs/needles, then I would use them in the 3LN3/5 carb bodies and make adjustments as needed, as the benefit of needles/tubes not wearing is good in the long term.

    The only difference between the 3LN3/5 to 3LN6/7 is a reduction in redline from 18,500 to 16,500, with a small change in cam profile. The EXUP is still present, and the carb diameter is the same at 28mm.
     
  8. skylinerd1

    skylinerd1 Member Premium Member Contributing Member

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    All I have is a zeal carb and this 3ln3 set that is needing a spring, and new needles and emulsion tubes for sure. Everything else looks ok to me. So I might aswell just replace all the springs in the 3ln3 with zeal springs. Are you saying just the springs will be ok or I need to do the complete black slider and diagphram with the springs? I would prefer to do just the springs and leave the sliders correct to the 3ln3 if I can get away with it....

    But it sounds like I will have to order the 3ln3 keyster kits to get needles and emulsions so I might aswell just replace every jet and needle I can that comes with the kit.
     
  9. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    Okay, I just went and reviewed your pictures of the carbs / slides you posted.

    They are the Zeal arrangement, which match my 2nd picture in my previous post

    If I were you, I would use all four springs from the Zeal set, with the plastic end and smaller spring that goes over the end of the needle.

    As for the slides, whether they are flat or rounded changes the off-idle throttle response. I'm sure someone will be along shortly the post the image of what influences carbs from idle to 1/8, from 1/8 to 1/4, to 1/4 half, from half to 3/4, from 3/4 to wide open, etc.
     
    Last edited: May 15, 2019
  10. skylinerd1

    skylinerd1 Member Premium Member Contributing Member

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    Ok that makes sense to me swapping the springs with the little helper springs off the zeal and leave it at that if I swap the complete slides them im likely in for changing jet and messing around territory..?
     
  11. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    I'd leave it at changing the spring sets over for the time being.

    The slide cutaway (straight or rounded) only has a small effect which may not even be noticeable.

    As the rounded cutaway slides are from the Zeal, you would need to check that they properly fit the slide bore and are not loose etc.
     
  12. beano

    beano Well-Known Member Premium Member

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    The outer diameter is the same but i believe the inner bore is smaller on the zeal. carb intake thickness.jpg

    Just my 2c but if i were you i would change the springs over, give the carbs a good clean, dont forget the merge chamber, set the fuel level correctly and everything else to spec as per the carb chart. Then run the bike and see how she goes.

    Dont bother buying anything until then.

    I know my67xr has had good luck with keyster kits and his word is gold on these bikes but im still on the fence about them personally.

    The zeal slide conversion is interesting and definitely worth a punt at some stage, but get her going well first and then play around with that kind of stuff or you'll find yourself chasing your tail very quickly.

    again just my 2c.............
     
    • Agree Agree x 2
  13. skylinerd1

    skylinerd1 Member Premium Member Contributing Member

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    Heres the difference between the springs.

    The slides look identical other than the moon cutout.

    The needle brown spacer is slightly thicker on the 3ln3 carb.

    IMG_20190516_124151[1].jpg
     
  14. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    I would stay with the original 3LN3 slide's and set up the carby's on your bike.
    Once they are running good then you could try swapping the later model slide's in.
    The cutaway's in the later slide's will make the carby's leaner so you may need to play around with jetting after installing them
    Just as a future reference could you measure how tall the cutaway's are on the late model slide's please ?


    The issue i had with the Keyster kit's is the main jet's were in the wrong box's, the inner carby jet's were in the outer carby box's and visa versa
     
  15. skylinerd1

    skylinerd1 Member Premium Member Contributing Member

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    Nobodies done a static measurement of the floats on the later bikes after doing the float levels? I see the card measurement at 16mm on one stickied thread but thats for the early 3ln1 bikes?
     
  16. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

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    If u want this one to complete your set , message me your name and address ... just pay for a Premium membership or make a donation to the forum

    spring 2 (Small).png spring 1 (Small).png
     
  17. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    See post #37 ^^ for this chart, check out the bottom line
    And 10.5mm fuel level above the line = 14.7mm float height, i found that out the hard way :headbang:

    [​IMG]
     
  18. skylinerd1

    skylinerd1 Member Premium Member Contributing Member

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    Back working on this thing again. Carb is ready to go back on again but I think I will check the valve clearances before I fill it back with water.

    Can someone point me to the front and rear wheel axle bolt torque specs? I had a search dunno maybe im missing the obvious?

    Just repainted and put a brand new tyre on the rear wheel because the old one had a puncture.... But cant find the wheel torque spec for this bike?
     
  19. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

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  20. skylinerd1

    skylinerd1 Member Premium Member Contributing Member

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    I ended up doing it up to about 70lbft. 10.2 kg/m = 77 lb/ft. Never seen it put in m/kg before?
     

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