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Ferris 400S Series RPM

#1

S

Skippydiesel

My friend has a Ferris 400S Series Zero Turn Mower. Fitted with a new (now 13 hrs) B&S 25 HP, Model 44T977, engine.
He feels that it does not seem to have the power/cut speed of the original 23 HP engine.

I have checked the engine speed:
  • No Load is 3060 rpm
  • Cutter deck engaged but not cutting grass 2750 rpm.

Does the engine speed, with cutter deck engaged, seem low to you?


#2

M

MParr

No load is 3,600 RPM

CXi Series Engines

<p>These V-Twin engines are specially designed for zero turn mowers and other high-debris applications to endure extended use in extreme conditions. Cyclonic air filtering keeps dirt out and extends engine life. The V-Twin design delivers more power, is naturally balanced for less vibration...
www.briggsandstratton.com www.briggsandstratton.com
Click on the Power Curve PDF and it confirms 3,600 RPM with no load.


#3

S

Skippydiesel

So how to get 3600 rpm?

Governor holding it at 3000 rpm


#4

S

Skippydiesel

Heeelp!

Tried to adjust external governor/lever position - Internal governor position seems to have changed/slipped. Won't return to original position. Engine goes straight to very high rpm. What to do??


#5

Tiger Small Engine

Tiger Small Engine

Skippydiesel said:
Heeelp!

Tried to adjust external governor/lever position - Internal governor position seems to have changed/slipped. Won't return to original position. Engine goes straight to very high rpm. What to do??
Click to expand...
You need to reset static governor setting. There are many pages of service manuals, forums, and videos showing you how to do this correctly. Then once that is set correctly, the dynamic governor setting should be set to about 3600 RPM without blades on (no load). There are springs, slots, tabs, etc. that can be tweaked to achieve correct RPMs. You will need a good tachometer to get it right.


#6

S

Skippydiesel

Tiger Small Engine said:
You need to reset static governor setting. There are many pages of service manuals, forums, and videos showing you how to do this correctly. Then once that is set correctly, the dynamic governor setting should be set to about 3600 RPM without blades on (no load). There are springs, slots, tabs, etc. that can be tweaked to achieve correct RPMs. You will need a good tachometer to get it right.
Click to expand...
Care to guide me to:
service manuals, forums, and videos showing you how to do this correctly
Click to expand...


#7

H

hlw49

Most engines turn around 3600 rpms and drop about 100 to 200 rpms when blades are engaged.


#8

M

MParr



#9

S

Skippydiesel

Hi MParr,

That was the video I saw before attempting to get a little more no load rpm.
Thought I had done it with an increase from 3000 - 3300 rpm.
Dont know what happened after that - was messing with the springs. Anyhow I noticed that the governor shaft had rotated 1 flat (It's got a hex end like a bolt) anticlockwise and would not turn clockwise (to the right). From then on had no governor action at all.
I am going to have to remove the engine from the mower. Open the shaft end crankcase and see what has happened internally.


#10

A

Auto Doc's

Basic governor adjustment: In your situation, opening the motor will just create confusion and unneeded work. The governors are simple and do not fail on these engines.

Remove the air cleaner components so you can study the linkage operation. Manually move the throttle shaft on the carburetor to determine the correct full throttle position.

The video that MPARR sent you gives the basic governor shaft adjustment.

Make sure your throttle cables has the correct adjustment. Many times, the throttle cable adjustment is the fault.

The governor arm has multiple holes for no load RPM adjustment. the farther down the lever the spring is moved the more tension placed on it. Your spring needs to be moved to allow for less spring tension.

Not all machines that these engines were used on require 3600 RPM. Most riders require 3600 RPM.

Engine RPM is not calibrated for loaded conditions. A drop of a couple hundred RPM is not uncommon, but excessive drop can be cutting deck related or partially restricted fuel supply.

Internally collapsing fuel lines are becoming more common depending on the fuel quality and if the machine is left in direct sunlight all the time.

A majority of poor engine performance problems start at the fuel tank. Years of use, dust and debris will collect in the bottom of a tank and slowly starve the fuel outlet and strain the pulse pump.


#11

M

MParr

The governor adjustments are separate from the high idle adjustment.


#12

M

MParr

Skippydiesel said:
Hi MParr,

That was the video I saw before attempting to get a little more no load rpm.
Thought I had done it with an increase from 3000 - 3300 rpm.
Dont know what happened after that - was messing with the springs. Anyhow I noticed that the governor shaft had rotated 1 flat (It's got a hex end like a bolt) anticlockwise and would not turn clockwise (to the right). From then on had no governor action at all.
I am going to have to remove the engine from the mower. Open the shaft end crankcase and see what has happened internally.
Click to expand...
You had better find a repair manual before cracking the crankcase on that new engine.


#13

M

MParr

Skippydiesel said:
Hi MParr,

That was the video I saw before attempting to get a little more no load rpm.
Thought I had done it with an increase from 3000 - 3300 rpm.
Dont know what happened after that - was messing with the springs. Anyhow I noticed that the governor shaft had rotated 1 flat (It's got a hex end like a bolt) anticlockwise and would not turn clockwise (to the right). From then on had no governor action at all.
I am going to have to remove the engine from the mower. Open the shaft end crankcase and see what has happened internally.
Click to expand...
I don't think that you're doing your friend any favor with his new
engine.


#14

Craftsman Garage

Craftsman Garage

@MParr where is the high idle adjustment? My briggs is only at 3k with the throttle pushed all the way up.


#15

A

Auto Doc's

There is a tab for the larger governor spring that has to be bent out slightly to increase or decrease the tension on the spring. The tab is hidden by the lower throttle linkage plate that bolts to the engine near each head.


#16

S

Skippydiesel

MParr said:
I don't think that you're doing your friend any favor with his new
engine.
Click to expand...
Video the best advice/information I have seen to date. My thanks


#17

S

Skippydiesel

Update!
Opened the B&S - governor mechanism in bottom of engine - evidence of overspeed.
Cleaned all the debris using a magnet.
Could not find any other damage.
Replaced governor mechanism using parts from another dead engine (same series).
Reassembled - hope to start tomorrow - wish me luck.


#18

H

hlw49

When you set the static gov adjustment be sure you are torquing the gov arm clamp bolt to 130 inch lbs. That sounds like what happend in th first place. If the rpms are still too slow you then bend the tab where the large gov spring hooks that is part of the speed control bracket. Sounds like a lesson bought.


#19

M

MParr

Skippydiesel said:
Update!
Opened the B&S - governor mechanism in bottom of engine - evidence of overspeed.
Cleaned all the debris using a magnet.
Could not find any other damage.
Replaced governor mechanism using parts from another dead engine (same series).
Reassembled - hope to start tomorrow - wish me luck.
Click to expand...
🤦‍♂️


#20

S

Skippydiesel

hlw49 said:
When you set the static gov adjustment be sure you are torquing the gov arm clamp bolt to 130 inch lbs. That sounds like what happend in th first place. If the rpms are still too slow you then bend the tab where the large gov spring hooks that is part of the speed control bracket. Sounds like a lesson bought.
Click to expand...
Thanks for that advice/observation - been torquing to "wrist click" will now get the torque wrench out.

Advice on idle spring static setting would be much appreciated.

Thanks


#21

S

Skippydiesel

Update;

Engine starts & runs very nicely. Have managed to increase no load speed to 3300 rpm. Will get some feedback from him after he uses it.


#22

A

Auto Doc's

Skippydiesel said:
Update;

Engine starts & runs very nicely. Have managed to increase no load speed to 3300 rpm. Will get some feedback from him after he uses it.
Click to expand...


#23

S

Skippydiesel

After about 2 hrs mowing there are no problems.


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