Briggs & Stratten 20HP won't start, backfiring through exhaust and carb.

[Novo]

YEs that is normal
Engine starts on full throttle then the governor will slow it down to whatever you have set the throttle to.
It is a balance between the spring tension and the force generated by the governor bobweights.
Stationary the bob weights are of course fully in so exert no force at all .

Bert
"prior" to installing the covers, but after I checked linkage/governor and started, I could watch the throttle butterfly. It did slow to an idle and rested against the idle screw. The engine was NOT (Put, Putting) as a too slow idle might be. Was generally purring as you probably would want. "lol sorry for the description but you get the idea" When I pushed to full throttle, it revved to what I would expect as a normal high RPM "Not like it was over revving" That's why I put the covers on and drove it around. After driving it around, I noticed I was no longer able to lower the throttle to a normal idle. Lastly I may should have mentioned, when I engaged the the blades, the engine didn't try to compensate speed for added load. Manually increased speed.
Is that normal?

One stupid question please: I haven't owned a riding mower in many years. Did they put a kill switch on reverse when the blades are engaged?
If so what a STUPID feature! Can't count how many times the mower died from me forgetting to disengage before backing up!
Anyways, Thank you for sticking with me!

 

[StarTech]

Yes they did on most models. And it is not so stupid as I personal know of two kids that ran over while the operator was mowing backwards. The one was a little girl that had to have part of her foot remove. Now was it really worth it to bypass that safety feature? Now that little girl will have to pay the price for the rest of her life.

Toddlers just don't realize the dangers when they want to show Daddy or Mommy something.

Plus know one used mower that previous bypass the seat switch by installing the wrong safety switch. Then operator got knock off his seat by a tree branch and mower ended up plowing into the side of his wife's new car while still cutting grass. The auto insurance almost didn't pay for the damages.

 

[Novo]

First the carburetor looks to be a Nikki carburetor. Should have an aluminum fuel bowl on the carburetor.

As the surging try doing a static governor adjustment as there maybe a slight ply in the linkages from wear. If continues after the adjustment then the carburetor needs cleaning and probably a new main jet as the o-ring on the jet is probably gotten loose. Just to note some these Briggs engines do surge when cold as Briggs run them a little too lean. Usually adding a little choke to smooth it out indicates a lean burn condition.

Also another thing I have over the years is if the idle speed screw is set too slow the engines will surge too as the governor closes the throttle plate too much. I usually set the idle speed by holding the throttle plate closed and setting the idle speed using a tach.

StarTech
Indeed it has an aluminum bowl.
On the governor, "with motor off" I loosened the governor arm "throttle set to full" and tried to turn the shaft "through the motor" the same direction as full throttle on the arm. It was already as far as it could be turned. I assumed it was already correctly set. The carb linkage has "choke" on after full throttle. "No separate lever"
My mother in-law has done literally nothing to this mower in 10 years. Oil change, carb rebuild or anything else. Battery changed and garage kept, that's all.
I agree with carb rebuild.

 

[Novo]

Yes they did on most models. And it is not so stupid as I personal know of two kids that ran over while the operator was mowing backwards. The one was a little girl that had to have part of her foot remove. Now was it really worth it to bypass that safety feature? Now that little girl will have to pay the price for the rest of her life.

Toddlers just don't realize the dangers when they want to show Daddy or Mommy something.

Plus know one used mower that previous bypass the seat switch by installing the wrong safety switch. Then operator got knock off his seat by a tree branch and mower ended up plowing into the side of his wife's new car while still cutting grass. The auto insurance almost didn't pay for the damages.

I totally agree with safety and have no intentions of by passing any switches. At 64, I too have seen many tragedies from lack of attention or bypassing safety devices.
My only thought was a 12v gear reduction servo could have served the same purpose to disengage the blades automatically with out user input, other than brake and selecting reverse.
As far as that goes, a rear proximity sensor could also be added to warn the user with loud buzzer for all objects. Kids, Pets, walls, fence, trees, shrubs, wife's flower garden, ect.....
I simple thought it could have been handled better and STUPID was NOT the proper word.