Engine rpms drop when releasing brake

[puttinalong]

Could there be a problem with the mower deck or any of the belt connections between the clutch and the deck? Normally if spindle or idler wheel bearings are bad, they'll make a lot of noise, but I'm wondering if there's something that causing more than usual power to be needed to start the blades moving. Check if it's excessively difficult to turn the blades by hand.

That is highly probable but I don't notice any unusual noises. I probably will pull the deck out and closely inspect it for anything unusual and report back. I'm certainly not going to rule anything out at this point. I did order an interlock switch for grins and giggles to see if that "magically" would remedy my rpms dropping during releasing the brake. I figured for $10, what did I have to lose at this point...

[puttinalong]

OK, I replaced ignition interlock switch....but like my wife says....I'm hardheaded. The switch has no different outcome as the original switch. The RPMs drop as well when just taking the brake off of the switch. As for the mower deck, that runs free and no hang ups. So I guess my next and final question is this...What would disengaging the interlock switch do to effect how the RPMs drop when no demand is on the mower??? Does disengaging this switch somehow engage the Hydro pump and that puts a demand on the engine? If the mower runs for a while and warms up, I remove the parking brake (disengage the brake) and the RPMs drop and pick back up so good it is hardly noticeable. After this I will just let it be until a bigger problem pops up with it and gets beyond my ability (which doesn't seem too hard to do here lately)....Penny for your thoughts???

[Arkie]

Just a armchair thought.
Similar to what KE4AVB indicates.

Try to see if the engine goes into a stall if the engine is accelerated from low idle to fast rpms.

Slow down the idling as low as possible and then manually open the carb throttle to wide open so as to simulate the governor opening the carb throttle fast and see if the engine has any momentary stall before it gains rpms.
You may have to remove the front hood and front clip from the mower so as to get good access to the engine.

Do this acceleration test with both warm and cold engine.

I suspect your engine is bogging right when the governor and carb is calling for more fuel.

If you have not done so already:
Install TWO new spark plugs of proper type. (one measley weak spark plug can make you feel really feel weak upstairs (like you are feeling now) when you encounter one.
Check or temporary remove remove the spark arrestor as a test.

[bgsengine]

Might help a lot if the engine model, spec, and serial were posted - Sears parts lookup for that model seems to sow a single cylinder Courage..?

[KE4AVB]

Hmmm, A single with twin exhaust. I haven't seen one yet; unless, it is a custom job.

Model #917.288613 should have came with a 26 hp Kohler Courage Plus 725cc (SV735) engine.

Going back to my knitting...

[puttinalong]

Hmmm, A single with twin exhaust. I haven't seen one yet; unless, it is a custom job.

Model #917.288613 should have came with a 26 hp Kohler Courage Plus 725cc (SV735) engine.

Going back to my knitting...

This is correct, it does have the 26 HP Kohler engine. I have tried the acceleration from low to high and it accelerates with no problem. Seeing that these plugs in the engine are the original, I will replace them as well. Only 70 hours on the plugs in it, but after 4 years in the mower, it couldn't hurt.

[puttinalong]

Might help a lot if the engine model, spec, and serial were posted - Sears parts lookup for that model seems to sow a single cylinder Courage..?

The engine is two cylinder Kohler Courage 26hp. Will get the serial number off the side of it later today and post this evening.

[Arkie]

Might help a lot if the engine model, spec, and serial were posted - Sears parts lookup for that model seems to sow a single cylinder Courage..?

Sears parts direct shows dual exhaust, but not much help in Id of engine.
Don't even show carb parts.
Correct, not enough real helpful info from the Sears site using just the mower model number.
Just some hints:
Make sure the flywheel is snug. (tight fit and not moving)
I probably would also use a Briggs spark gap tester (not the type with a light bulb) and while the engine is cold then hot I would carefully inspect the spark on each cylinder in a darkened place so as I could see the intensity of the spark real good. (and try it while the engine is stuttering if possible)
I've seen coils (especially magneto type) produce a weaker spark to one cylinder and the comparison spark gap test (using the Briggs spark gap tester) of each cylinder while the engine is running made the spark test visually more apparent. (sometimes these engines when hot would be starting on only one cylinder when hot or warmed up and then run on both cylinders after it started but one cylinder was weaker due to weak ignition. engine would start ok if cold but flood easily and hard to start SOMETIMES when hot. (and new spark plugs would help but problem would re-surface in few hours)
Very hard to find this type ignition problem when it first starts because it's usually intermittent and erratic.
Sometimes you can ground a spark plug with a screwdriver on a multi cylinder engine while it's idling slow and compare the rpm droop so as to see if each cylinder is producing equal power. If you can't slide the insulator boot up on the wire for such insert a solid bare wire into the spark plug boot or make a extension adapter using a piece of 1/4 inch ID copper tubing so as to apply a ground after the engine is running.
Don't just pull a plug wire off while the engine is running because this will usually produce a ignition feedback upset to the other cylinders or to yourself.