Bobbing oil dip stick?

[7394]

That is IF it's blown around the edge, leading to the outside of the engine, right? Because the pressure inside the sump won't increase a whole lot, if it's an internal gasket leak. Will it?
Briggs don't normally fail from edges leading to the outside. I've only seen them leak between the valves and the opening to the push rods.

Valid point Sir..

 

[PTmowerMech]

Get an extractor (if you don’t already have one) and suck all that old bad cloudy fuel out, and blow out tank.
Suspected bad head gasket:
While at idle, quickly push throttle to WOT, then at WOT quickly go down to idle, waiting a few seconds in between. Does a puff of smoke come out? After running a bit, open dipstick and look for a little smoke coming out. Neither are definitive tests. Now perform a compression test and leak down test, watching for air escaping out of cylinder head with valve cover off. Just did one yesterday with 40% loss. Anything under 20% is acceptable. Single cylinder Briggs (ie: 31P677) is very common for bad head gasket.

So I took the fuel line loose from the pump (tank side, and drained about 6oz. This was after it had been sitting all night. And it was clear as a bell. So I put that line back on and pulled the fuel line off the carb , and pumped out about 1/2 quart, and it was milky, had tiny fragments in it and still a little more water. So I replaced the fuel pump and pumped a few oz and it was clear.
I removed the bowl and it wasn't just real bad. But you could tell had been coated in water. Kind of chalking film over it.
I have the carb apart now and in the USC, looking for a rebuild kit.

I sure wished the Stens 520-024 was for this model.

 

[Forest#2]

I've seen them dual throat Nikki's do some weird things when they get upset.

Do You see a Nikki carb number on the side of yours?
Is that the Aluminum bowl or the Steel bowl Nikki? The reason I ask is the Aluminum bowl kit is different than the steel bowl Nikki and the steel bowl type has two different kit's.
One size does not fit all on the Nikki's, close but no cigar.

If it has a Nikki name on the carb I would try to re-kit before going the Clone route is another reason I ask.

 

[PTmowerMech]

I've seen them dual throat Nikki's do some weird things when they get upset.

Do You see a Nikki carb number on the side of yours?
Is that the Aluminum bowl or the Steel bowl Nikki? The reason I ask is the Aluminum bowl kit is different than the steel bowl Nikki and the steel bowl type has two different kit's.
One size does not fit all on the Nikki's, close but no cigar.

If it has a Nikki name on the carb I would try to re-kit before going the Clone route is another reason I ask.

Yes is an aluminum bowl nikki.
number on top
590851 266
4818 5B


Bottom


The Partstree diagram looks like the right one.

44S777-0016-G1 - Briggs & Stratton Vertical Engine Carburetor, Fuel Supply Parts Diagram​

One difference I do see is the choke shaft. The one I have, the shaft goes all the way through and has a screw on the other end that secures a washer to keep it from sliding out.

 

[PTmowerMech]

Double post

 

[PTmowerMech]

One thing to check with being a Nikki twin barrel is loose main jets.

Rebuild parts ordered. Now just waiting to see what I either forgot to order, or what wrong part I did order. lol
I did get lucky and find a few things I'd bought before, that got lost in the move.

I do have one question, that I think pertains to the main jets. Do they have anything to do with the L & R that's stamped on the carb body? As in two different size jets that are particular about being L or R? Partstree only listed 1 jet (other than high altitude).

 

[Forest#2]

Here is some info about your later model Nikki BRIGGS aluminum bowl CARB that I have on file for reference. This info will answer some of your questions about the Briggs Nikki's. Note the L in your first picture, that is the left side reference for the jets location. The texture of that carb appears that maybe it has been in the Usonic few times before the pictures. The steel bowl Nikki's are the older models and are of at least two different designs. I do not have a very good track record of trying to use the China clone replacement Nikki's although I have taken parts from the clones such as o rings, etc and installed into the real Nikki and get a good run. Amazon Prime has a free refund policy if their carbs don't work correctly so that is usually where I get Clones for testing.
I have tested the Nikki carb using both of the jets as the larger size and got a good run. I've drilled the smaller to same size as the larger jet. I also use a gasket and RTV with good results at the intake instead of trusting the O-ring. Sometimes the intake two intake gaskets come in a kit, but if not I just make them.

These are rebuild links to assisting in cleaning, kitting, and where to find parts
AT A REASONABLE PRICE.

Try using Google Chrome as the browser for these links. Sometimes Microsoft edge will 404 out.



Tip: When looking up Nikki carb kit numbers use Briggs ahead of the part number INSTEAD of Nikki

Nikki carb rebuild links, videos and also a parts supplier on ebay.

Google Chrome will have to be used to access these links. Microsoft edge will not work.

https://bgsupply.weebly.com/helpful-videos.html



to look at parts, kit, jet, etc to go to different part number, etc click on the 3 bars menu in the upper left corner. You will have to choose Briggs and Stratton to see the Nikkii carb parts

https://sawzillaparts.com/carburetor-kits/briggs-stratton/



and another link to repairing the Nikki’s plus others
This is the steel bowl with the BLACK emulsion tube. Pay attention to the jet holes after you remove the top plate for cleaning them.
Your aluminum bowl is the later model and slightly different but some good tips here.

https://outdoorpowerinfo.com/repairs/

 

[PTmowerMech]

Here is some info about your later model Nikki BRIGGS aluminum bowl CARB that I have on file for reference. This info will answer some of your questions about the Briggs Nikki's. Note the L in your first picture, that is the left side reference for the jets location. The texture of that carb appears that maybe it has been in the Usonic few times before the pictures. The steel bowl Nikki's are the older models and are of at least two different designs. I do not have a very good track record of trying to use the China clone replacement Nikki's although I have taken parts from the clones such as o rings, etc and installed into the real Nikki and get a good run. Amazon Prime has a free refund policy if their carbs don't work correctly so that is usually where I get Clones for testing.
I have tested the Nikki carb using both of the jets as the larger size and got a good run. I've drilled the smaller to same size as the larger jet. I also use a gasket and RTV with good results at the intake instead of trusting the O-ring. Sometimes the intake two intake gaskets come in a kit, but if not I just make them.

These are rebuild links to assisting in cleaning, kitting, and where to find parts
AT A REASONABLE PRICE.

Try using Google Chrome as the browser for these links. Sometimes Microsoft edge will 404 out.



Tip: When looking up Nikki carb kit numbers use Briggs ahead of the part number INSTEAD of Nikki

Nikki carb rebuild links, videos and also a parts supplier on ebay.

Google Chrome will have to be used to access these links. Microsoft edge will not work.

https://bgsupply.weebly.com/helpful-videos.html



to look at parts, kit, jet, etc to go to different part number, etc click on the 3 bars menu in the upper left corner. You will have to choose Briggs and Stratton to see the Nikkii carb parts

https://sawzillaparts.com/carburetor-kits/briggs-stratton/



and another link to repairing the Nikki’s plus others
This is the steel bowl with the BLACK emulsion tube. Pay attention to the jet holes after you remove the top plate for cleaning them.
Your aluminum bowl is the later model and slightly different but some good tips here.

https://outdoorpowerinfo.com/repairs/

Thank you for that. I'm going to save that Sawsilla website. Looks like they've got good prices.

 

[7394]

Google Chrome will have to be used to access these links. Microsoft edge will not work.

Firefox works as well, just saying..

 

[PTmowerMech]

Firefox works as well, just saying..

I use Brave. There's no commercials on Youtube.