Briggs 20hp V-Twin Intek (407777)

Discussion in 'Mechanic and Repair' started by briggerman00, Oct 14, 2007.

  1. briggerman00

    briggerman00 LawnSite Member
    Posts: 10

    Hello,
    Kind of new here but this seemed like the best place to go, yesterday I was mowing and noticed that my engine just did not idle down low enogh, so being knowledgeable enough that when you turn your governor shaft on this particular engine then you can obtain a lower idle rpm, the problem is this, I did this and now is seems as if the engine has a higher rpm than before, any idea's on what has happened, any idea's on how I can solve this problem?
    I have a Briggs, Model#407777, Type#0124, has the two barrel carburetor, has a new carb. on it.
    email address is briggerman00@charter.net
    Thanks
    Jeff
     
  2. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,022

    Jeff,

    What you need to do is get the governor back to the proper factory adjustment as below;


    1. Loosen screw holding governor arm to governor crank.

    2. Rotate throttle plate linkage from idle position to full throttle position.
    Note direction of rotation of the governor arm attached to the throttle
    linkage.

    3. Place and hold the linkage in high speed position.

    4. While holding the linkage in this position, Use a appropriate tool to rotate
    the governor shaft until it stops in the direction noted in step 2.

    5. tighten screw holding governor lever to governor crank. Torque to 35-45
    in. lbs. (2.8-5.0 NM).

    6. Before starting engine, Manually actuate governor linkage to check for binding.


    Once the governor is re-adjusted properly clean and lube the control plate assembly and carb throttle shaft then see if that helps the high idle problem.

    If not there are two springs behind the control plate, The smaller diameter of the two is the governed idle spring, It connects to a non-moving tang on the control plate. Bend this tang to weaken the pull on the spring to lower the governed idle.
     
  3. briggerman00

    briggerman00 LawnSite Member
    Posts: 10

    Ok I have tried that and still I get the high idle speed, is there something that might have come loose on the inside that is keeping the governor rod from turning all the way to the right, I mean it only turns about 1/16 to 1/8 of an inch.
     
  4. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,022

    Check the throttle cable hold-down clamp, It's possible the cable slipped/stretched and is now not returning the control plate lever to idle position.
     
  5. briggerman00

    briggerman00 LawnSite Member
    Posts: 10

    checked the throttle cable, and everything is fine there, have a question how far should the governor shaft be able to turn, is it possible something might have slipped inside the engine?
     
  6. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,022

    Anything is possible, Was this engine revving higher than normal before you tinkered with the governor shaft ?

    There shouldn't be much more than 1/16 to 1/8 turn of movement in the shaft, That's why I over-looked what you said about that.

    Can you grab the throttle linkage going to the carb and move it so the engine idles lower ?
     
  7. briggerman00

    briggerman00 LawnSite Member
    Posts: 10

    The engine was a little high on the idle side before I messed with it, and yes there is only about a 1/16 to 1/8 inch movement in the shaft.
    I can take the throttle linkage and move it to make the engine idle down but it goes right back to where it was, I stopped by Big R store this afternoon to get a new throttle linkage, and two new springs, ithink that someone before myself has messed with this motor before and I am just hitting the problem that they had, I have put a new carb on it and that was a 100% better, but just having the idle issue is really getting me, so your help is greatly appreciated believe me.
    Thanks
    Jeff
     
  8. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,022


    The above is happening due to the governed idle spring I mentioned on top, Look at it closer and try to adjust.
     
  9. briggerman00

    briggerman00 LawnSite Member
    Posts: 10

    OK I have adjusted the small tang on the throttle lever assembly, have put two new springs on the governor assembly, have adjusted the governor arm and governor shaft properly, now the question I have is this, on the back of the throttle which the cable attaches to is a piece called the throttle restrictor tab, when this is turned to low speed is this tab suppose to push the governor arm up so it can only idle?
     
  10. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,022

    That is only a safety device to keep the engine from revving up when the throttle is at the slow (idle) position. It is not designed to push on the governor arm to MAKE the carb throttle shaft touch the idle adjustment screw.

    This engine among others have the governed idle for smoother low speed operation and quicker response when throttled up.

    One other thing just came to mind,

    You say you replaced the carb. Check the link from the governor arm to the carb, This link is super close to the intake on the carb end. If the link is installed the wrong direction or up-side down it could hit the intake and cause a high idle speed.
     

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