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Carb Sync Tool

Discussion in 'TY Tech Advisor board' started by grizztracks, Jan 22, 2012.

  1. grizztracks

    grizztracks Tech Advisor Tech Advisor VIP Member

    Messages:
    1,564
    Location:
    Scio, NY
    Country:
    USA
    Snowmobile:
    FX Nytro RTX, RS Vector
    I made my own sync tool out of 12' of 5/16" vinyl tube filled with a little transmission fluid. I mounted the tube in a "U" shape on a 4' 1X4 pine board and filled it so I had around 22" of fluid in each side of the "U". You can only sync two carbs at a time but I've had good results with it. #3 carb (stator side) is preset so you sync 1 and 2 to it. There are only two screws to adjust (3 screws on 4 cylinder engines) which are located between 1-2 and 2-3. It's an easy adjustment that can make a big difference in performance.

    Here are a few pictures of my Carb Sync Tool and it being used to sync the carbs on a Vector.
    Note: never run the engine with only one side of the sync tool connected or you'll suck the oil out of the tube.

    [​IMG]

    Carb sync (tool connected for #2 adjustment)
    [​IMG]

    Carb #2 out of sync
    [​IMG]

    Carb #1 slightly out of sync
    [​IMG]

    Sync'd carb
    [​IMG]
     
  2.  
  3. TOMBOB

    TOMBOB Paying Member VIP Member

    Messages:
    145
    Location:
    Saranac,Michigan
    GRIZZTRACKS,
    quesstions
    1. is 12 ft of hose total or for one side or booth

    2. at what speed do you test idle /wot

    3.do you fill the tube up to 22" +/-

    4. sync two carb's to 3rd at the all same height

    5. 5/16 hose o.s.----?

    thanks for all infor you give for this site

    TOMBOB
     
  4. TOMBOB

    TOMBOB Paying Member VIP Member

    Messages:
    145
    Location:
    Saranac,Michigan
    GRIZZTRACKS,
    43 degrees in michigan today so made your sync tool. less than twenty buck. booth 1&2 carb were out of sync. very simple idea but very effective.

    thank again, very helpful

    TOMBOB
     
  5. aVenture

    aVenture Newbie

    Messages:
    363
    Location:
    Quebec
    This differential type of guage always worked good for me, compared to the absolute type sold on the market. It is very sensitive, and contrary to a absolute connection, you can give it some gas after equalizing carbs so to have a feel how close the slides are opening together. All in all, this is not an absolute reading you need but the difference between cylinders, and it does it more precisely. The industrial one i bought for my bike has been collecting dust.

    Oh.... i use antifreeze..
     
  6. grizztracks

    grizztracks Tech Advisor Tech Advisor VIP Member

    Messages:
    1,564
    Location:
    Scio, NY
    Country:
    USA
    Snowmobile:
    FX Nytro RTX, RS Vector
    Sorry I didn't get a chance to answer your questions before you put together the sync tool.

    I used 12' total of 5/16 O.D. tubing which is just enough to mount it on the board and still reach the carb's. I cut about 4-5" off one end of the tube and inserted a tee for the fuel pump hose which is removed from the carb being sync'd.

    I filled the tube with transmission fluid so that both sides have about 22" of fluid measured from the bottom of the "U". I found it easier to actually suck the transmission fluid into the line rather than trying to pour it in.

    Syncing the carb's should be done at an idle with the engine at operating temperature (1350-1400 rpm). After each carb adjustment bring the engine rpm up then allow it to return to idle so that the carb settles. This is a differential type sync tool so all that matters when making an adjustment is that the fluid is level in both sides of the tube which indicates that the two carbs are balanced.
     
  7. 4strokeluvr111

    4strokeluvr111 Pro

    Messages:
    370
    Location:
    NW Wisc.
    Country:
    USA
    Snowmobile:
    05 Vector
    14 Vector LTX
    IMO....anybody with a carb'd Vector (any carb'd Yamaha 4S???) that likes to tinker even a little bit on their sled should build one of these!

    Easy to build and use. The hardest thing was getting the right amount of tranny fluid in! :o|

    ;)! Thanks Grizz! ;)!
     
  8. Horizonls

    Horizonls Newbie

    Messages:
    3
    How would you proceed to syn an Rx-1 with 4 carbs, only two carbs have the vac lines attached to them and the other two are capped off?
     
  9. grizztracks

    grizztracks Tech Advisor Tech Advisor VIP Member

    Messages:
    1,564
    Location:
    Scio, NY
    Country:
    USA
    Snowmobile:
    FX Nytro RTX, RS Vector
    If a carb has a vacuum line for the fuel pump pull it and reconnect it to the tee in the sync tool line. If their is no vacuum line then pull the cap off, connect the sync tool and then use the cap to plug the tee in the sync tool line.
     
  10. theewarrior

    theewarrior Newbie

    Messages:
    121
    Location:
    Canada, Cape Breton
    All I can say is this works ....thank you!!!
     
  11. gosnek

    gosnek Newbie

    Messages:
    12
    Location:
    Arkona,Ont,Canada
    Made one of these today,did a super clean on carbs was still having some issue, warmed up sled and hooked it up carbs where out of sync man what a difference after the sync. This site rocks :rocks:
     
  12. grizztracks

    grizztracks Tech Advisor Tech Advisor VIP Member

    Messages:
    1,564
    Location:
    Scio, NY
    Country:
    USA
    Snowmobile:
    FX Nytro RTX, RS Vector
    Glad I could help ;)!
     
  13. Bradford

    Bradford TY 4 Stroke Guru

    Messages:
    367
    Location:
    NB Canada
    I built one of these too. The only differnece is I used 2-smoke oil instead of transmission fluid. Finally found a use for that oil!
     

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