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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. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Factory float height is 14.7mm so you should have them close enough.
    You'll need to retune the mixture screw's again after changing the float height's
     
  2. skylinerd1

    skylinerd1 Member Premium Member Contributing Member

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    I think we might be on the right track.

    I started it with the carbs set as above and adjusted the mixture screws to 3.75 turns out. Im thinking I should try another half turn out and see what happens.
    It now idles way better (almost perfect actually I think not knowing how these should idle) and does rev out better but still has hesitation if you crack the throttle quickly. I looked at the spark plug and it looks same as before white on the tip after idling for a bit.

    So I tried the clear tube method again and was kinda perplexed.... noticed one carb is leaking slightly...sigh (maybe its slipped one of those bowl seals without me noticing).... so they deff got to come out again either way. When I move the clear tubes up they leak down to just above the line on the carb body. Sometimes they seem to leak down further than that.... Im not sure. Im finding it quite difficult to get an accurate reading how im doing it. The photo is the only time I could get it to stop leaking down to much.

    Heres some photos of how I set that up.
     

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    Last edited: Jun 15, 2019
  3. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    With the pvc tube's, let any fuel evaporate out of them, then heat up the end about an inch in from where it goes onto the drain barb of the fuel bowl with a cigarette lighter or hot air gun, when the pvc is hot enough bend it to a right angle then let it cool.
    this should stop the fuel from draining out when you lift each hose up near the fuel bowl's and make it easier to check each fuel level.
     
  4. skylinerd1

    skylinerd1 Member Premium Member Contributing Member

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    ^^ Yeah thats a good idea.

    I just tried it again they were near empty so I cracked the drain plugs and let them fill to get their level then quickly pushed them in a bit closer to the carb body. They look very good. Maybe a touch lower than 10.5mm. I'll try bending them properly later and try again.

    How many turns out until pilot screws start leaking fuel? They shouldnt really leak even when almost loose with that oring huh? Im just trying to tell if that tiny fuel leak is from the pilot screw or just from the bowl seal..... I should be able to go a fair bit more out on that screw without them leaking than 3.75 turns out huh?
     
  5. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Start the bike and take it for a ride if you can, to get it up to operating temp then adjust the mixture screw's in to get the highest/smoothest idle speed.
    Drop the idle back down to normal speed (1600rpm) and move onto the next mixture screw and repeat

    With the Keyster kit's my FZR run's the best with the mixture screws set at 1.75 turn's out.
     
  6. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Last edited: Jun 15, 2019
  7. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Okay, sounds good. Have to check these things.
     
  8. skylinerd1

    skylinerd1 Member Premium Member Contributing Member

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    Yep I get what you were getting at. When you compare a new needle to the old ones that were in this carb set I have the difference is night and day. Infact I doubt that carb would of ran at all with those in that state there's hardly any spring left in them at all.
     
  9. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    I worked that one out a while ago
    It's posted here- https://2fiftycc.com/index.php?threads/fzr250r-3ln3-bdst28-carburetors.9643/

     
    Last edited: Jun 15, 2019
  10. skylinerd1

    skylinerd1 Member Premium Member Contributing Member

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    Ok so im having to goto fairly wide swings to get it to drop idle in both directions. on cyl 1 and 2 I end up at 1.5 turns out to get the idle to drop then go out to 6 turns to get the idle to drop so set it at 3.75 turns out.

    Cylinder 3 im getting no change (I think it was running initially now its playing up) I touch the pipes 1,2 and 4 are to hot to touch. cylinder 3 is touchable but still quite warm I can touch my fingers on it for a good amount of time before it gets to hot unlike the others. I think on my initial tune this cylinder was running and I rode it around the block and the thing actually felt pretty good other than the hesitation when turning the throttle quick. I shut it down after trying to tune the cylinders a bit more and now its playing up a bit so im hoping its just spark. This is also the carb that has a slight leak I think at the bowl.

    Cylinder 4 seems to be 1turn out to get the idle to drop and then 6 turns out again but its very had to hear so I set it to 3.5

    When I initially started the bike from cold it was running on 3 cylinders and I could physically see the spark on cyl 2 jumping onto the head cover from the boot. (this is the one I knocked the wire off and refitted it)... I pushed it and the cylinder stated running and its been fine since.

    So im thinking I'll pull the plugs on cyl 3 and 4 and have a look place them on the valve cover and see what sort of spark I get.

    I will pull the carbs again and look into this leak aswell.
     
  11. skylinerd1

    skylinerd1 Member Premium Member Contributing Member

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    Yeah must of been just a band connection or something. When I pulled both those plugs and run it on the other two cylinders I can see them sparking but its not a bright white spark its kinds of a bluey/orange weak looking spark obviously quickly with it idling on 2.

    Could that coil pack be a bit sus? or do the coils cross over? Are the coils paired in cyl 1&2 then 3&4 or is it done another way?

    Im struggling to get much of a change in idle on those two cylinders the outer one I can hear drop idle at about 1 turn out then I take it back out to 6 turns out and cant hear much of any change.
    The inner cylinder number 3 the exhaust is now to hot to touch again so its deff running but I cant get much of any change in idle even when wound fully in on that pilot screw.

    Again cylinder 3 is the carb thats leaking so I think I will pull that again and try figure out this leak. Cant see exactly where its leaking weather its just the drain screw or the bowl seal is hard to tell.

    The best I can get it running as is seems to be with the pilot screws at about 3.5 to 3.75 turns out. Still slight hesitation most likely because of whatever is going on with this cyl 3 and 4 I think.
     
    Last edited: Jun 16, 2019
  12. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Spark plug's 1 and 4 run off the same coil, then 2 and 3 off the other coil

    Try taking the spark plug cap's off the lead's and check them internally for corrosion
    Look inside the spark plug end, you will see a flat head slot in the end, undo that and pull them apart.
    Check for any corrosion on the spring, washer and resistor, clean them up and apply some dielectric grease to help protect them from more corrosion
    Screw the lead's back on and check the spark again.

    When testing for spark, make sure all spark plug's can fire, if one is left off the coil lead it can damage the TCIs' internal's

    Have you checked the Ohm's reading's of the ignition coil's ?


    With the mixture screw's set at 3.5 to 3.75 turn's out, can you smell it being rich at the exhaust ?
     
    Last edited: Jun 16, 2019
  13. skylinerd1

    skylinerd1 Member Premium Member Contributing Member

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    The saga continues...
    Looks like it might of killed a resistor pill in one of the boots. I dismantled and cleaned and lubed all 4 boots after reassembly one measures 20mega ohms (I should of measure it before hand but they are simple enough that im confident its reassembled right). The other three are between 10.5k ohms and 13.5k ohms.

    The coils measure 3.2ohms. I couldnt get another measurement off the coil or the leads than that don think the probe tips are long enough?

    So I might try source a second hand set of boots the part number on the boot is TDT-137a
     
  14. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    You need to set the multimeter to 20k Ohm's (20,000) to test the secondary side
     
    Last edited: Jun 16, 2019
  15. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

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  16. skylinerd1

    skylinerd1 Member Premium Member Contributing Member

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    Its one of those auto ranging ones... Oh I was just measuring the coil secondary the wrong way. both coils measure 14.7 and 14.8 k ohms.

    The next issue I will probably have if I use those NGK SD10f boots is these leads have been cut down so much and the rubber is so damn hard its incredibly difficult to get the boots to screw into them without atleast drilling a pilot to get them started. The 2nd one I ended up drilling didnt seem to have the greatest connection with it arcing to the head... I probably need new ignition wires as well really will a local supplier like repco carry anything like this stuff?
    Has anyone had success removing those plastic clips that retain the ignition wires to coil they seem on the wire pretty well I couldnt move the wire in them at all. Is there another sneaky method to retain the new wires into the coils?
     
    Last edited: Jun 16, 2019
  17. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Get yourself a Morgan Carbtune too.
     
    • Agree Agree x 1
  18. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

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    Its just common 7mm HT wire

    https://www.gsparkplug.com/ignition...MIrczz3_Tt4gIVmJ3VCh3F8wJAEAAYAyAAEgJX_fD_BwE


    Now I spend time posting to offer assistance to people .... so if you would kindly read the thread I linked above in my previous post then you will find out about removing the clips and leads from the coils on an FZR :aggressive:

    https://www.2fiftycc.com/index.php?threads/help-required-please-fzr250.10045/page-3#post-115690

    And if your drilling into the leads then they are stuffed ... Im still using the original leads on my FZR and the caps screw in easily
     
  19. skylinerd1

    skylinerd1 Member Premium Member Contributing Member

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    Is it possible to have a problem with one carb where even when you screw the pilot screw right in nothing happens?
    I find that odd. Is that a potential sync issue?? I have not ordered that sync gauge yet but will do.

    The other three cylinders I can tune one and two are quite noticeable in the idle changes when turning the screw. number 4 not as easy but still can tell. Number 3 nothing happens when screwing in or out on that pilot screw. All 4 cyl ex pipes are hot to touch... I find it really odd that I cant shut down number 3 with the pilot screw.

    So I guess im going to have to compression test this thing now.

    There is just the slightest bit of blue smoke if you really give it a rev when sitting on the side stand other than that no crazy exhaust smoke it looks clean cant smell fuel.

    I rode it around the block and other than that number 3 cylinder causing the engine to bog on quick throttle application you would think this thing runs pretty good.

    Im suspecting this engine may have been run without water and maybe the rings (on number 3 in particular have lost their tension). Thats my suspicion.
     
    Last edited: Jun 24, 2019
  20. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Are the carby fuel level's all the same now, 10.5mm above the line ?
     

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