Briggs and Stratton Adjusting Governor 3.5HP

Learn how to adjust the RPM on a Briggs & Stratton lawn mower

this will fix a mower which is revving too low or too high. This is accomplished by adjusting the governor spring

Tools/Parts Required 

  • Flat Head Screwdriver
  • Phillips Head Screwdriver
  • Needle Nose Pliers

Step 1.

Remove the bracket holding the throttle cable in place. Remove the air filter with a flat head screw driver.

Step 2

If the mower is idling at lower than normal RPM tighten the governor spring by cutting it shorter, this will increase the tension on the throttle and raise RPM. If the mower is idling at higher than normal RPM stretch the governor spring slightly to decrease the resistance placed upon the throttle.

Step 3

After adjusting the governor spring to the desired amount of resistance test the lawn mower (with or without the air filter, if testing without air filter only test briefly). if everything is now working replace the air filter and throttle cable bracket.



13 Comments

  1. I spent more than an hour trying to find info to work out what sort of tension I needed on both springs from the Briggs and Stratton site (some-one had put the throttle spring onto a random hole in the plastic [rocker] arm). your tutorial was a nice and simple explanation/example of what it does and what I need to aim for – thanks!

  2. Why not just move the speed adjustment lever (the thing that the spring is hooked to) instead of bending up the spring ? It moves to release or increase tension on the spring.

  3. Go to briggsandstratton.com/eu/en/support/faqs/adjusting-the-governor

    To reset the governor: Loosen the nut that clamps the governor arm to the governor rod. Turn the governor rod toward the full throttle direction until it hits a stop. Hold it there, and tighten the nut again.

    Adjust the top no-load speed by bending the tang that the spring connects to.

    Do not adjust by cutting or stretching the spring. Buy a new spring if necessary.

    • A couple of things here to point out. One, the governor may not be an internal one, but an external plastic vane around the flywheel. In a perfect world, an engine governor will evenly match rpm for load required, up to its load limit. On most mower engines, its a much coarser slide than on some finer equipment. The gist of the governor on mowers is to simply push the throttle open more when a load hits it, most noticeably the blades being engaged. And the happiest medium you can get for the design, is for the engine to operate within a specified optimum range. Everything down to the camshaft design centers around top performance within just a few hundred rpms.

  4. After much mucking around I found that the following works wonders for older wind vane governed motors that are worn.
    1. Tighten spring
    2. Cut 2 cm off the end of the governor vane plastic
    3. Chop 5 cm off the end of the exhaust muffler
    4. Drill two 5mm holes in the lower end of the crankcase ventilation valve on the inside.
    5. remove air filter and replace with foam sponge.

    Nothing will match the power now!

  5. I have nust gad what the mower repair shop called a cable adjustment, as the mower would not shut off. I had to wait for fuel to run out. I used it for 5 minutes this morning and all good, this afternoon same problem, the motor won’t stop, the cable appears to be moving up and down, what can i do.
    Thanks
    Penny

    • Hi Penny

      When the throttle cable is in the off position there is a small metal tab that contacts the metal plate the throttle cable is connected too. This is how the mower is turned off. When worn this part can become unreliable and require adjustment. If you move the throttle to the full speed position and remove the air filter so you can see the throttle linkages you should be able to locate the small metal tab that should be contacted when the throttle is in the off position. When you have located this you should check it is clean and that it is able to contact the moving throttle plate when in the off position. If it does not make contact either the tab is bent or the throttle cable requires adjustment.

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