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Help Carb balancing

Discussion in 'Maintenance' started by Anne K, Aug 9, 2020.

  1. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Heres the FZR250 3LN1 carbs


    Sync screws 3LN1 carbs.png
     
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    Last edited: Aug 30, 2020
  2. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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  3. Anne K

    Anne K Member

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    Thanks for sharing this @GreyImport, I just bench synced conveniently using a broken E string I had I’ll finish it off with the sync tool. I’ve gotta add, bench syncing as a beginner is easier than trying to do while they’re on the bike. Trial and error lol
     
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  4. Anne K

    Anne K Member

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  5. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    In my view bench syncing as an experienced old fart is easier also .... I have an old school carb balancing set but painful to use ... my FZR has run with just a bench sync for years

    It was going to be my next suggestion but thats great u have already got there :thumb_ups:

    My expensive , highly professional special carb syncing tool ... sourced from the local music shop :D

    sync tool.png
     
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  6. Andych

    Andych Senior Member Premium Member

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    I hope you aren’t flashing your G string @GreyImport


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  7. Anne K

    Anne K Member

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    I was so happy to have synced the carbs... but when I put them back on the bike I forgot to connect the fuel line to the carbs and accidentally dumped about 2L of fuel onto the starter and God knows where else it leaked into.. now it won’t start (facepalm!)


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  8. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    It'll dry up quick, you may need to readjust the mixture screw's once they're synced with your digital tool
     
  9. Andych

    Andych Senior Member Premium Member

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    At least it didnt go up in flames... could have been a whole lot worse. Keep at it, you will get there :)
     
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  10. Anne K

    Anne K Member

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    I thought I’d check the fuses because the bike wouldn’t even crank.. and found this, accidentally disconnected the blue and white wires when I took the battery out to charge it [​IMG]


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  11. Cj Ryder

    Cj Ryder Member

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    This adds help when fitting springs
     
  12. Brandon Otte

    Brandon Otte Active Member Premium Member

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    Why do the mixture screws need readjusting once synced?
     
  13. Frankster

    Frankster "Play stupid games, win stupid prizes" Staff Member Premium Member Ride and Events Crew

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    I tend to find you have to play with the idle setting as you sync your carbs. The syncing process can sometimes cause your idle to drop or raise as you're doing it. The air/fuel mixture screws aren't as much of a problem, but when your carbs come down from a rev, they can sometimes go rich or lean depending on the mixture settings. This manifests itself as the engine revs dropping so low that the engine wants to stall or the revs hanging high for a while until they return to idle.

    Just like vacuum syncing your carbs, you might want to 'sync' your mixture screws across all 4 carbs. They're never exactly the same across all 4 carbs. I think @maelstrom has a good technique on his website. I may be wrong, but that's where I think I read about adjusting down until nearly stalling and then adjusting up until nearly stalling and whatever the middle value is, should be the ideal setting. e.g. 1 turn nearly stalls the engine and 3 turns nearly stalls the engine, therefore 2 turns is the ideal setting for that carb...repeat process with the other 3 carbs. You want the carb vacuum sync to be so right that after blipping the throttle, the engine revs return quickly and without fluctuation, to idle. That's my understanding of why you should sync air/fuel after vacuum.
     
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  14. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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