A properly adjusted governor can maintain a steady engine speed regardless of changes in the terrain and other conditions that increase the work of the engine. These conditions are known as the "load." When engine speed starts to rise or fall in response to a change in the load, the governor responds, opening or closing the throttle. If you adjust engine speed manually, using the equipment controls, the governor's job is to maintain the new setting.
Your engine contains either a pneumatic governor or a mechanical governor. Remove the blower housing to determine which one your engine uses. Pneumatic governor linkages connect to a pivoting air vane next to the flywheel. On a mechanical governor, the linkages connect to a governor shaft.
For Model 90000/10000 engines, please view our tank mounted carburetor linkage.
For either type, follow the steps below to adjust your governor for best performance. NOTE: Governor procedures vary widely depending on the make and model of the engine. Check with your Authorized Dealer for the speed settings for your equipment.
Inspecting The Governor
With the spark plug lead disconnected and secured away from the spark plug, check that the governor linkages are attached and move freely by pulling gently on the throttle lever. This should stretch the governor spring while pressing on the governor lever. If not, check that the governor spring and the link to the governor lever are properly attached to the throttle lever.
Springs and linkages that are not attached may be reconnected if they are in good condition. Twist them carefully into place to ensure that the delicate springs and linkages aren't permanently bent or stretched. Do not use pliers or other tools to bend or distort links or springs. Replace the governor spring if it is overstretched and replace the linkages if they appear worn.
Adjusting The "Static" Setting On A Mechanical Governor
The following procedure eliminates play in a mechanical governor between the governor crank (the arm that protrudes from the crankcase) and governor system components inside the crankcase. This procedure does not apply if your engine has a pneumatic governor.
Loosen the clamp bolt on the governor crank until the governor lever moves freely.
Move the throttle plate linkage until the throttle plate is wide open. (To find the wide-open position, first position the throttle lever against the idle speed screw or a fixed stop plate. The throttle is wide open when it is all the way in the opposite direction.) Note the governor arm's direction of rotation as you move the throttle plate to the wide-open position. This is important for the next step.
With the throttle plate wide open, use a nut driver or wrench to turn the governor shaft in the same direction that the governor arm traveled.
Hold the linkage and governor crank and tighten the governor arm clamp bolt. Move the linkage manually to make sure there is no binding.
Some engines contain a shorter, smaller, "secondary" governor spring to discourage stalls when the engine is operating at idle under a light load. Under these conditions, the secondary spring keeps the engine at a "governed idle" speed slightly above its true idle speed. The idle speed screw is always set at less than the engine's governed idle speed. The procedure for adjusting governed idle varies depending on the engine model. Consult your Operator's Manual for the procedure or your model.
Keep in mind that the secondary spring affects all governor settings. If the governor on your engine has a secondary spring, you need to adjust the governed idle before setting the engine's top no-load speed.
Tang Bending And Other Adjustment Methods
The tang bending tool is the most common tool for governor spring adjustment. It's a simple metal lever with forked ends used for grasping and bending the tabs, or tangs, on the governor lever, spring anchor and other engine parts. Bending a tang increases or decreases the extension of the governor springs.
If the governor lever has multiple spring holes, you can increase top no-load speed by selecting a hole that is farther from the pivot point on the governor lever. On some engines, an adjustment screw alters governor spring tension, increasing or decreasing top no-load speed. Fine adjustments may still require the use of a tang bending tool.
Setting Top No-Load Speed
If your engine races when you set your controls to HIGH, you need to reduce the engine's top speed under no-load conditions. Ask your Authorized Dealer for the proper top no-load speed setting for your model. (If your governor contains two springs, skip to "Setting Dual-Spring Top No-Load Speed," below). The most common method for adjusting top no-load speed is to use a tang bending tool to bend the spring anchor tang to stretch or relax the spring.
Attach the Tiny Tach to the engine's white ground wire with the alligator clip. The red wire should be wrapped around the spark plug lead. Run the engine for five minutes so it reaches its operating temperature.
Place the equipment on a hard, smooth surface with the engine running and the controls set to HIGH. Decreasing top no-load speed by bending the tang toward the governor spring, until the manufacturer's specified speed setting is attained. Increase top no-load speed by lengthening the spring.
If your engine has a mechanical governor, proceed with the static governor adjustment
Setting Dual-Spring Top No-Load Speed
If your governor contains two springs, the smaller, shorter spring is the secondary spring and must be adjusted to prevent stalls.
Attach a tachometer to the engine. With the engine running, bend the secondary spring tang so there is no tension on the secondary spring.
Bend the primary governor spring tang until the engine speed is 200 rpm below the manufacture's specified top no-load speed.
Bend the secondary governor spring tang until the engine reaches its top no-load speed. Ask your authorized service dealer for the top no-load speed setting for your engine.
If your engine has a mechanical governor, proceed with the static governor adjustment.
NOTE: Please read and abide by any applicable Safety Information (PDF) before performing any engine work. This information is not meant to take the place of work performed by a Briggs & Stratton Authorized Dealer. Terms and Conditions apply to all of our information provided on this website. Always be sure to read and understand your engine Operator's Manual.