ENGINE won't REV UP

[bertsmobile1]

Ok it goes like this.
When you pull the throttle fully open, the throttle wire pulls on that big spring on the bottom which pulls the governor arm ( the bit that come out of the engine ).
The top of the govenor arm is connected to the throttle linkage which goes to the throttle butterfly at the carb.
When the engine is not running , pulling the throttle on fully should move the throttle link far enough to make the butterfly open and rest against the stop which in your photo is not happening.
So the metal ( not the plastic ) arm on the carb should be as far counter clockwise as it can go. This is wide open.
The tiny spring over the throttle linkage that looks like it is pulling against itself is there to smooth out the movements of this arm.
If you push & pull the arm you will see a tiny amount of stretch in this spring it is just a damper

When the engine is running the governor pulls on the throttle rod which will close down the throttle butterfly and make the engine go slow.
So I will guess that the Govenor arm is in the wrong position, or the govenor spring is in the wrong place.

Now I did notice that you have buffed the magnets on the fly wheel.
This is a no no as you can affect the strength of the magnets by doing this carelessly.
If you want to remove the rust then use a rubbing block with some wet , wet & dry paper.
Now when you did this that will have changed the air gap and the air gap controls the spark timing so it will have to be reset.

To take things any further we need to know the engine details which should be stamped ino the engine cowel near the spark plug.

 

[Street_Rod_Guy]

Thanks for the informative reply.
Couple clarifications....
Sorry if I implied somewhere the engine wasn't running or wouldn't start. It is.
In the photo I took the throttle wasn't up fully (in the choke position) so as it would make the butterfly open on the choke.

The govenor arm nor spring has every been off the back mounting point. It was just disconnected from the butterfly on the carb. The photo shows the throttle at the slow position here (maybe this is where you meant for me to take the photo from with the throttle in the full fast position - I wasn't sure where you wanted me to take the picture 'from' or what you wanted to see; so I just took a few pictures and started from there). There was only one place to put the spring and link when I put it back on (one small hole and one bigger one). Also as a 'fail safe' I took picks of everything before I disassembled anything to avoid putting anything in the wrong spot upon replacement; and this is where they were originally.

As far as buffing we did use a piece of sandpaper on a air grinder. Dad is very familiar with how magnets and timing; so we doubled checked it after we cleaned it to make sure the gap was correct. Since It's only running 1/2 speed right now; I can't say for sure the timing is off; but running at the speed it is now; it sin't skipping or sputtering or anything. Appreciate you notcing and mentioning about that because when we get it running wide open if it seems out of time, we can adjust it.

I want to thank you for the wealth of info and the time it took to write it and carefully look over the pics. You seem very knowledgeable and I'm sure many folks here could count on you to help them out with issues. I'll tinker a bit more (really not sure what else to do I hadn't done. But I'll tinker a bit more - raining here now so I can't use it anyway. LOL.

 

[Street_Rod_Guy]

Well I finally gave up on it and took it to a small engine mechanic.
I looked it over and he said everything externally was as it should be.
They just called and said the cam was bad. It'd cost $200 to fix it.
The mower is 10 years old. I know Troybuilt makes a great product; so now I am wondering if I should fix it; or buy a new mower...??
Just curious what else may be coming down the road....

 

[ILENGINE]

Well I finally gave up on it and took it to a small engine mechanic.
I looked it over and he said everything externally was as it should be.
They just called and said the cam was bad. It'd cost $200 to fix it.
The mower is 10 years old. I know Troybuilt makes a great product; so now I am wondering if I should fix it; or buy a new mower...??
Just curious what else may be coming down the road....

And that is what I was suspecting was wrong, but didn't have enough info to determine.

 

[Street_Rod_Guy]

The guy had a brand new 21 HP motor on hand and offered it to me for $600 + tax.
It's going to cost close to $250 to fix mine; or I can buy the new motor and install it myself for just an extra $400. To me that sounds like the smart route to take. The motor also comes with a two year warranty.

 

[Rod BS]

Hi Gang
Brand new here - just joined. always nice to have a place to do fixes yourself
Anyway here is my issue
I have a TroyBuilt Bronco riding mower
It has the 18.5 hp engine

I was cutting grass yesterday and noticed it started losing power.
So today here is what I had gone threw to try and fix it.
I put in new oil; cleaned plug; took off and cleaned out carb (it was already clean I noticed when I removed it) Disassembled everything from the gas tank to the place where carb mounts onto motor.
Put in new gas, checked lines for leaks.

Engine will start but not rev up. It does not smoke, skip, or anything like that - just seems to get revved up to about 1/2 speed, and won't rev no higher. When I put the throttle on high it seems just about 1/2 speed, and as I decrease the speed on the throttle the motor revs stays the same until I get to about 1/2 speed, then it decreases and as I lower it some more; then it will just dies. Never smokes, coughs, or sputters.

I have NO clue what is causing this, and like I said it ran fine while cutting the grass yesterday until I was just almost done. So this came up all of a sudden. Had never gave any indications of problems before, and I have used the mower off and on all winter.

SO what kind of ideas can you folks throw out that I might fix it easily.
I am guessing it won't be anything 'major' it's just trying to figure out where to start.

This is hard to explain...when your foot brake is released is it coming all the way back because this is what determines the tension on the drive belt to make it go faster or slow it down. What can happen is dirt and grass can build up on the of the base of the pedal arm where it contacts with the cross member of the chasis. This is what happened on my Craftsman and it took me a while to figure it out.