Ferris 400S Series RPM

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?

No load is 3,600 RPM
Click on the Power Curve PDF and it confirms 3,600 RPM with no load.

So how to get 3600 rpm?

Governor holding it at 3000 rpm

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??

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.

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...

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

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.

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.