Engine speed on an mtd push mower

newtz

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What controls the engine speed on a 4 1/2 hp 123cc ohv MTD yard machine push mower? I bouf=ght this mower used and threw the deck away to put the engine on my 20" Lawn Boy trimming mower.

This mower has cables for a choke and a shut off switch. When I was changing the air filter I noticed the choke was almost closed. The range of motion was fron3/4 closed to closed. There was no sliding cable to adjust, all the choke cable mounting points were fixed. I bent the linkace so the choke would open but I had to bend it back to get the mower to run. This tells me that the carb is too lean, but ny eyesight is no longer good enough to disassemble ,clean, and adjust a carb. The plug was neither sooty or oily so I just cleaned and capped it. and put some seafoam in the gas tank.

The engine runs strong and starts easy now but at insane rpm. I am afraid it is going to destroy itself. I see no adjusting screws on the carb, How doI slow the engine down.
 

Fish

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You need to put up some pics, and an engine model number.
 

tom3

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Being an OHV engine it is a fairly new design motor and the carb is probably built to be non-adjustable and have an automatic choke. Choke would be mostly shut when motor is cold and not running. For speed control you can usually see a spring on the carb linkage that is attached to a metal tab on the carb mount. This spring is countered by the speed governor. Usually have to bend this tab to set the engine rpm to suit you.
 

newtz

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I can find no numbers on the engine, I think mtd put them on the mower deck which I don't have, my back is acting up so I can't disassemble the air cleaner assembly to take pics right now.
 

Fish

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I can find no numbers on the engine, I think mtd put them on the mower deck which I don't have, my back is acting up so I can't disassemble the air cleaner assembly to take pics right now.
If you can at least put up any pic of the engine, we can have a better idea of what you have.
 

StarTech

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With a 20" blade, the max allowable engine RPM is 3627 which produce a blade tip speed of 19,000 Ft./Min.
 

newtz

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I finally got pics, the deck is a 20: Lawnboy that I use as a trimmng mower that started blowing oil everywhere. I bought a used 22" MTD but it was too wide for some ov the places I had to mow so I put the handle, controls and motor from the mtd on the lawn boy deck. It was working ok but the choke would not fully open so I bent the choke linkage toget the choke to fully popen and close/ The yellow knob is the manual chole control.

It runs strong now but the rpm is way too high. Sounds like a car with a brick on the throttle. Was not doing that before I1594512469227.jpeg1594512469227.jpeg1594512469227.jpeg1594512469227.jpeg1594512469227.jpeg
 

newtz

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I am having a devil of a time posting photos, after I drop one it won't take any morehere is the 2nd 0ne, I tool 7.it would not let me upload more photos, the file size was to big and I don't know how to reduce them.
 
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Scrubcadet10

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Upload them to an image hosting website, they give you a link, and put the link here.
 

tom3

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Are these from a phone camera? I usually have to download to the computer, to paint, reduce size about 40%, then up load. Still get a really good picture.
 
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