Briggs 18 HP operating RPM's

Discussion in 'Mechanic and Repair' started by cableman, Jun 13, 2006.

  1. cableman

    cableman LawnSite Member
    Posts: 14

    I have a Briggs 18 HP model 422437-0719 on a Grasshopper 1822 mower and I need to know what RPM they run at WOT? I installed a Tiny Tach and right now I'm running at WOT 3150 with no load and with load it drops to 2900. This seems low, how much drop should you have with a load on? What do I need to adjust to keep from having such a drop?

    Thanks Cory
     
  2. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    3600 rpm is a good no load speed on this engine, The amount of rpm drop depends on the amount of load applied. You may try replacing the governor spring as it may have gotten weak from heat being enclosed in that mower, Also make sure the spring is in the center hole on the governor arm.
     
  3. cableman

    cableman LawnSite Member
    Posts: 14

    This is what I tried this morning- The only way I was able to get 3600RPM was by moving the govenor spring from the middle to the far out side. It now maintains 3600 rpm no load and 3500 plus with load. It does drop when I get into a little taller grass but that could be normal. Since I had to move the spring to the outside hole is it a problem leaving it there or is the spring weak?
    Cory
     
  4. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    The pic. below shows the RPM rating per hole, So if you had to move it to the outer most hole to get 3600 then I would say the spring is weak and needs replacing. By moving the spring also changes the sensitivity of the governor which could have something to do with the bogging you encounter now.

    Briggs Twin Gov Spring.JPG
     
  5. cableman

    cableman LawnSite Member
    Posts: 14

    Thanks for the info, I had to order the spring so when it comes in I'll reset back to the middle slot and give that a whirl.
    Cory
     

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