Walbro Carburetor on Briggs & Stratton Model 28R707

Yes, black smoke is too rich, blue is oil and white is steam/condensation.

Surging is normally caused by air entering the inlet manifold or governor.

All Carburetors have adjustment
Needle height
Main Jet size
Idle Jet air control (often hidden under a silver disc).

surging

https://www.google.com/search?q=18hp+Briggs+and+Stratton+surging

Carburetor adjustment

https://www.google.com/search?q=18+hp+briggs+and+stratton+carburetor+adjustment

..

Normally, you just go by the Briggs and Stratton engine and model numbers. B&G carbs

https://www.google.com/search?q=replacement+carburetor+for+a+18.5+brigs+and+Stratton

Or Walbro

https://www.banggood.com/buy/briggs-stratton-carburetor-walbro-697202.html

I would be surprised if Jack didn't have one!

Briggs and Stratton 31E707-0111-E1 Parts Diagram for ...

https://www.jackssmallengines.com > briggs-stratton > c...

Briggs and Stratton 31E707-0111-E1 Carburetor - Walbro &Nikki, Cylinder Head, Fuel Supply, Kit - Carburetor Overhaul - Walbro & Nikki Exploded View parts lookup by model. Complete ... (Carburetor Part Numbers 696179, 697202). $6.18.

https://www.google.com/search?q=Walbro+697202

..

Here's a replacement on eBay. $55


Carburetor Carb Engine Motor Parts For Briggs Stratton Walbro LMT 5 4993...

About 625 results (0.89 seconds) Search Results

Why wont my engine start - Briggs & Stratton

www.briggsandstratton.com/.../why-wont-my-engine-st...

Briggs & StrattonThe most common reason an engine will not start is due to an interruption in fuel ...(such as Briggs & Stratton carburetor cleaner to clean carburetor parts and body. ...gasoline be purchased in small quantities, not more than a 30 day supply. ... that canflood the engine, or cut the air supply enough that engine will not run.Missing: inch ‎major

Information about the Carter, Kohler and Walbro Carburetors

gardentractorpullingtips.com/carbfuel.htm
Information about the Kohler Carburetor, Various Fuels and Fuel Systems. ... (Updated 5/23/15); Repairing Various Older Briggs & Stratton Carburetors. ... If used on a smaller engine, due to the larger venturi, the engine will not receive the ... which converts to 1.181 inches (30 ÷ 25.4 = 1.181"), but actually measures 1.200".

Notes on the Troubleshooting and Repair of small Gasoline ...

www.repairfaq.org/sam/lmfaq.htm
May 19, 2015 - Timing; Lawn mower will not start after the blade hit an obstruction; Flywheel ... on Briggs and Stratton repair; Experience with Briggs & Stratton carburetor .... NEVER attempt to run a gasoline engine indoors. ..... For 2 stroke engines, special oil (not the usual 10W-30/40 type motor oil, nor WD40 or 3-In-One!) ...

Briggs & Stratton - YouTube

Could be that the needle is stuck in carb, or else the fuel pump diaphragm is bad. Check the pump, thats what I would check first.

You need to determine if you have a Nikki or Walbro carb. The Nikki bowl is held on by two phillips head screws and the Walbro bowl is secured by either a single bowl nut or a anti-backfire soleniod (two wires going to it). Your problem is probably the seat in the carburetor. We see very few float problems since most of them are plastic.

If you have a Walbro with the anti-backfire solenoid you will need to get a slim 1/2 open end wrenc the access the "flats" on the solenoid to unscrew it.

The brass seat is replaceable in the Walbro along with the needle. If it's a Nikki, you may need to replace the carburetor.

Hope this helps

Sounds like your carb is flooding. Inside the carb, there is a simple valve that shuts off the fuel flow when the fuel bowl is full. If this valve fails, or if the float sinks, then too much fuel is forced into the cylinder and will wash past the rings and into the crankcase. This causes the engine to run very rich. You need to remove, clean and overhaul the carb, and change the oil and sparkplug and probably the air filter too. Find the model, type, and code numbers on the engine and go to www.partstree.com , www.ordertree.com , or your local repair shop to get the needed carb overhaul kit. Some B&S engines have an option of carbs, so look for a name on the carb itself...probably Nikki or Walbro. The carb kit is not very difficult to install, but make sure to get everything very clean before reassembly.
Good luck.

Here are various graphics from the B&S Intek Twin governor. Maybe they're close . . .

Drain oil... it is full of gasoline due to a bad float pin and rubber gromet in your carb. When your float pin and gromet fail, gas just keeps flowing into your carburetor, eventually flooding your motor with gas and oil mix.