Wide open throttle

jjt0883

Member
Joined
Jun 15, 2022
Threads
2
Messages
17
My problem is with the following issue. The operation of the governor does not seem to be working properly. When the engine is at rest, the throttle is open. When I start the engine it runs wide open and will not idle down after starting. The governor spring will seemly not allow the throttle to close and therefore remains wide open. Any ideas as to what is causing the problem.

Kohler SV530-3222 MTD 17 HP (12.7 kW) Engine

Operation
As the governor gear rotates, centrifugal force causes
the flyweights to move outward as speed increases. As
the flyweights move outward, they cause the regulating
pin to move outward.
The regulating pin contacts the tab on the cross shaft,
causing the shaft to rotate. One end of the cross shaft
protrudes through the side of the crankcase. The
governor lever is clamped on the protruding end of the
shaft and connected with linkage to the throttle lever
on the carburetor, so any rotation of the shaft causes
corresponding movement of the throttle plate.
When the engine is at rest, and the throttle is in the
‘‘fast’’ position, the tension of the governor spring holds
the throttle plate open. When the engine is operating
(the governor gear assembly is rotating), the force
applied by the regulating pin against the cross shaft
tends to close the throttle plate. The governor spring
tension and the force applied by the regulating pin are
in ‘‘equilibrium‘‘ during operation, holding the engine
speed constant.
When load is applied and the engine speed (and
governor gear speed) decreases, the governor spring
tension moves the governor arm to open the throttle
plate wider. This allows more fuel into the engine;
increasing engine speed. This action takes place very
rapidly, so a reduction in speed is hardly noticed. As
the speed reaches the governed setting, the governor
spring tension and the force applied by the regulating
pin will again be in equilibrium. This maintains the
engine speed at a relatively constant level.
The governed speed setting is determined by the
position of the throttle control. It can be variable or
constant, depending on the application.
 

DaveTN

Well-Known Member
Joined
Jun 12, 2011
Threads
16
Messages
670
Rivets....The cops tried to arrest me the other day! Why?
Trying to "Impersonate a Small Engine Mechanic!" ;)
 
Last edited:

jjt0883

Member
Joined
Jun 15, 2022
Threads
2
Messages
17
I adjusted the governor arm counterclockwise and retightened it. The movement was about this much 1/16 if that. Very little movement. The problem seems to be spring tension. The spring attaches to the throttle arm. The spring attaches at the middle of the level governor arm and there is no other location. pic2. The other end of the spring attaches in the 6/27 pic within the linkage grouping. The linkage by itself holds the throttle open without the spring being attached pic3. When the spring is attached the throttle stays open and will not close or respond to the speed control handle.
 

Attachments

  • Mon 6:27 2.jpg
    Mon 6:27 2.jpg
    186.1 KB · Views: 12
  • Mon 6:27 3.jpg
    Mon 6:27 3.jpg
    168.4 KB · Views: 12
  • Mon 6:27.jpg
    Mon 6:27.jpg
    196.4 KB · Views: 12

sgkent

Lawn Addict
Joined
Sep 27, 2017
Threads
30
Messages
1,679
my understanding, limited, is that a throttle is held open with the spring, and a governor closes it. If the governor is attached then it is not governing. On my engines the governor is a vane. It is attached to the throttle to pull it back while a spring pulls it open. The actual RPM is a balance between the two. Some engines, and I think yours is one of those, the governor is inside the engine case.
 

VegetiveSteam

Well-Known Member
Joined
Jun 1, 2022
Threads
0
Messages
355
I adjusted the governor arm counterclockwise and retightened it. The movement was about this much 1/16 if that. Very little movement. The problem seems to be spring tension. The spring attaches to the throttle arm. The spring attaches at the middle of the level governor arm and there is no other location. pic2. The other end of the spring attaches in the 6/27 pic within the linkage grouping. The linkage by itself holds the throttle open without the spring being attached pic3. When the spring is attached the throttle stays open and will not close or respond to the speed control handle.
Did you also turn the governor shaft counterclockwise as far as it would go before re-tightening? The way I always explained a mechanical governor adjustment was to loosen the governor arm on the governor shaft. Move the governor arm which ever direction needed to open the throttle on the carb all the way. Some go clockwise and some go counterclockwise so if you just remember to move the arm to open the throttle all the way you don't need to remember clockwise or counterclockwise. Now once you have the governor lever moved to wide open throttle turn the governor shaft the same direction until it stops. Then tighten the governor arm fastener. One thing to be careful of on a Courage single is, when moving the governor arm to open the throttle plate on the carb to wide open, is to be careful not to let the link between the governor arm and carburetor flex. That is a very long link and it is easy to put too much pressure on it causing it to flex. If you tighten the governor arm fastener with the link flexed, as soon as you let go of it the governor is out of adjustment. If you've done the governor adjustment correctly and you get no resistance from the internal governor gear then something is wrong with the governor gear inside the block. The governor spring's job it to try and over speed the engine. The governor gear's job with proper adjustment is to not let the governor spring over speed the engine.
 

Rivets

Lawn Royalty
Joined
Mar 11, 2012
Threads
55
Messages
14,743
According to the manual you are attaching the spring in the correct holes, but I have 4 questions. 1. After you adjusted the governor, how far does the governor arm move, engine not running? 2. When you attach the spring, engine not running, can you manually close the throttle by pushing on the governor arm? 3. When the engine is running can you push the governor arm to reduce and increase engine speed? 4. What color is the spring we are talking about? It should be red and is part #20-089-11S. Let us know the answers to these questions and we’ll have a better idea on how to help you.
 

jjt0883

Member
Joined
Jun 15, 2022
Threads
2
Messages
17
According to the manual you are attaching the spring in the correct holes, but I have 4 questions. 1. After you adjusted the governor, how far does the governor arm move, engine not running? 2. When you attach the spring, engine not running, can you manually close the throttle by pushing on the governor arm? 3. When the engine is running can you push the governor arm to reduce and increase engine speed? 4. What color is the spring we are talking about? It should be red and is part #20-089-11S. Let us know the answers to these questions and we’ll have a better idea on how to help you.
Question 1. it has free movement, throttle stop to wide open
Question 2. yes I can, but at rest it stays open quarter way open
Question 3. wide open !!
Question 4. red
I almost pulled the throttle shaft out of the carb trying to control the speed. Is that suppose to happen?
 

StarTech

Lawn Royalty
Top Poster Of Month
Joined
Feb 19, 2020
Threads
76
Messages
10,221
Remove the carburetor and check that the throttle shaft vane (butterfly) is still attached. I had several engine in the shop last year where the vane mounting had came out and one engine partiallly suck it into the intake manifold. IF the screws are missing then you need to pull the cylinder head and make they are not in the cylinder. Sometime they pass all the way through to muffler and other times they don't. That when the cylinder, cylinder head, and/or piston get damaged.
 
Top