Model 23

[JandL]

Greetings,

I have an engine here in the shop that is as old as I am. It is a Briggs and Stratton 23 203010 228611, it will start if cold and run fine for about 4-5 minutes then act like its running very rich (light black smoke out exhaust) and shut down. No restart at all. I have installed a kit in the carburetor, cleaned and gaped the points (.020), changed spark plug, and I get the same thing. It will fire ONCE after it shuts down if I put gas in the inlet tube, then nothing. If I use starter fluid it will run it out then nothing. I have spark all the time, air is not a problem and its getting fuel. By my logic it should be running all the time however such is not the case. Any ideas would be helpful.

[bgsengine]

Greetings,

I have an engine here in the shop that is as old as I am. It is a Briggs and Stratton 23 203010 228611, it will start if cold and run fine for about 4-5 minutes then act like its running very rich (light black smoke out exhaust) and shut down. No restart at all. I have installed a kit in the carburetor, cleaned and gaped the points (.020), changed spark plug, and I get the same thing. It will fire ONCE after it shuts down if I put gas in the inlet tube, then nothing. If I use starter fluid it will run it out then nothing. I have spark all the time, air is not a problem and its getting fuel. By my logic it should be running all the time however such is not the case. Any ideas would be helpful.

Compression? Valve Clearance? Also depending on the type oi ignition system your point gap may be wrong - some of them had a spark advance mechanism as part of the camshaft.. compression release may be sticking - you need to identify the specific design of the components (Antique engine manual should help with that)

[JandL]

Additional information:

Valves:
Intake ~.012 Spec is ~.008
Exhaust ~.022 Spec is ~.018

Compression: ~80 psi

Ignition system by matching parts in the book on the Briggs and Stratton power portal Antique Engines book is a Magnematic. According to the book, point gap is .020 which is what it is set at.

[HondaG100]

Doesn't do a good job of explaining the rich running but it sounds like ignition system failure due to it warming up. Check for spark when it quits.

[KE4AVB]

It may be case of weak spark as starter fluid would ignite easier than regular fuel. You said to cleaned and adjusted the points but have you tried installing a new condenser (capacitor)? It may need changing in this older of an engine. Depending how you checking for spark also can be a problem. It needing to jump a .166 air gap to fire good under compression as it is a lot harder to jump a .030 gap under a compression load with fuel added.

Also as BGS suggests check the cold vs hot compression as it may be losing compression as it warms up.

[JandL]

Thank you for your inputs, the customer does not want to put the money into fixing this engine so the story does not have a happy ending. On to the next issue, which is driving in the parking lot as I type this....thanks again.

[bper]

Hi JandL - This engine had the old Flo-jet carburetor on it if I remember right. These were made out of pot medal and very subject to warpage between the bowl and top. They also often got corroded and pitted where the fuel nozzle seats in the bottom half. This caused them to run rich just like a leaky N&S.

It is a Briggs and Stratton 23 203010 228611, it will start if cold and run fine for about 4-5 minutes then act like its running very rich (light black smoke out exhaust) and shut down.

A good way to tell if this is the problem is remove the air cleaner and bracket and see if fuel is leaking from the carburetor intake when setting for awhile. One way of getting around all this if the leak is not bad is turn the fuel off from the tank when ever the engine is shut down.This is the cheapest way out as these carburetors are probably not available anymore. You might also turn the fuel off when it starts smoking to see if it clears up before running out of gas. I'm going on memory here and it's getting worse every year, so I may have missed something. I no longer repair engines as I'll be 70 this year. Good luck on your project - bper (Bruce)

Hi everyone - I do stop by once in awhile just to read some of the posts. I'm afraid my small engine knowledge is going by the wayside fast. I did work on quite a few model 23's though in years past. A very good engine.
Hello everyone that's still here from the old forum and Springs a coming.

[bgsengine]

Hi everyone - I do stop by once in awhile just to read some of the posts. I'm afraid my small engine knowledge is going by the wayside fast. I did work on quite a few model 23's though in years past. A very good engine.
Hello everyone that's still here from the old forum and Springs a coming.

Awesomeness! Glad to see you're still kickin' around!

[bluemower]

here is a manual and parts listing from the B&S web site.

http://www.briggsandstratton.com/lam/en ... mestic.pdf