B&S 725ex 190 cc made 3/2013. Engines starts 1st crank, misfires and surges until hot

[Boudreaux In Eunice La.]

Re: B&S 725ex 190 cc made 3/2013. Engines starts 1st crank, misfires and surges until

Here's the video It's only 1 minute 27 sec but it shows the main things to look for, enjoy ~!~!

https://youtu.be/qOm-D93Y9-k

 

[sp80]

Re: B&S 725ex 190 cc made 3/2013. Engines starts 1st crank, misfires and surges until

Ok now that you got into detail about it , i'll bet you have the shiny carb on there. The later models of those engines do run rough then smooth out... Briggs found a new place to make their carbs ?? Not the good carbs like on the older ones.

I have changed a few of those already.... Thinking they were chinese carbs...... Those mowers have to be perfect to run smooth...

Speaking of chinese! i just purchased a B&S 591868 spark plug from Amazon, which is marked 591868 ON THE Package, but is stamped 992300C on the plug. It was pre-gaped at less than .020 and Package is marked made in china. I checked at home depot and the 591868 package contains the 992300c plug made in china also. I will report after trying that plug, however I am still working with the BR2-LM NKG.

 

[sp80]

Re: B&S 725ex 190 cc made 3/2013. Engines starts 1st crank, misfires and surges until

I agree on a choke issue Purvis... I thought it was a auto choke system from the first post he put up... Hence the questions about spring and such..

Sp 80 take the cover off the air box and remove the filter.. .......... Then look at your choke... Note where it's at...

Then start the engine and keep a eye on the choke butterfly until a few minutes have passed.... It should be warmed up good in 3 minutes.....

Then report back to us what you see ...........

Plus Tard Mon Ami .......Oh I got a video on how that works.. I'll post it later ~!~!

OK guys. I will run the engine and check the choke butterfly, then report back.

 

[sp80]

Re: B&S 725ex 190 cc made 3/2013. Engines starts 1st crank, misfires and surges until

Here's the video It's only 1 minute 27 sec but it shows the main things to look for, enjoy ~!~!

https://youtu.be/qOm-D93Y9-k

Watched it thanks.

 

[sp80]

Re: B&S 725ex 190 cc made 3/2013. Engines starts 1st crank, misfires and surges until

OK guys. I will run the engine and check the choke butterfly, then report back.

I decided to try the low tech approach. I sprayed the choke, throttle springs and carb. with carb cleaner while running, through the hole in the air cleaner base plate. I added 1 once of Berryman- B12 chemtool fuel injector/carb cleaner to one gallon of gas and filled the lawn mower gas tank. I ran the lawn mower engine for 35 minutes. It ran rough for about 5 minutes then smoothed out. I shut down the engine. Today I checked the spark plug. It was normal(not Fouled.) I regapped NGK BR2-LM Plug to .025 from .020. Engine started first crank ran a little rough for about 5 minutes, then began to smooth out. It ran smoothly for 35 minutes on my driveway. Throttle handle was secured with a rope. I shut engine down and restarted. On restart it ran smoothly without the normal initial roughness and continued to run smoothly. This was the first time in 4 yrs. that it did not run roughly after restarting the engine once it had been shut down. I decided not to take the air cleaner plate off to check the choke, because I had not obtained a new gasket and I was afraid I might damage the gasket when I removed it. Since the plug was not fouled, and because it smoothed out after it warmed up I reasoned that the choke opened after warm up.

My thanks to Mr. Boudreaux and the other gentlemen who took the time to respond to my inquiry and offered helpful, detailed suggestions. You helped resolve my Snapper mystery. My machine runs better than it ever has.

Thanks to the Forum or providing this service.

 

[Boudreaux In Eunice La.]

Re: B&S 725ex 190 cc made 3/2013. Engines starts 1st crank, misfires and surges until

Hey SP 80 don't go thanking me yet or anyone on this forum.... You FORGOT about Rivets in post # 2 when he shot you that info on the MAIN JET or as it's called a BOWL nut...........

I forgot about that being a issue..... It still can be an issue if it is not cleaned from the top hole down into the side holes...

That bowl nut or bolt as we call them is the main jet in the carb you have on that engine.... All 3 holes have to be cleaned well with a wire or tip cleaner and sprayed with carb cleaner well......

Also the air box has a filter that has to be put in place...... I also forgot about the O ring that the carb slips onto the intake tube....... Did you change that too ??

Ok Mon Ami Let us us know ~!~!

 

[sp80]

Re: B&S 725ex 190 cc made 3/2013. Engines starts 1st crank, misfires and surges until

Thanks for the detailed information Rivets.

 

[Boobala]

Re: B&S 725ex 190 cc made 3/2013. Engines starts 1st crank, misfires and surges until

I don't know if they're still made, but Champion used to make spark plugs for two-cycle engines to deal with plug fouling. The ground electrode (if that's what it's called) only extended halfway across the center electrode. Maybe one of those plugs, with a split-the-difference gap of .025 would do the trick.

With that said, I don't think it's a spark plug problem. Sounds like a choke not opening fast enough.

cpurvis : If you check a 2 cycle plug you'll see it only goes 1/2 way across the electrode, also some speed shop engine builders "cut" the plugs like that, thought was, it gave a broader spark in the cylinder.....

 

[cpurvis]

Re: B&S 725ex 190 cc made 3/2013. Engines starts 1st crank, misfires and surges until

cpurvis : If you check a 2 cycle plug you'll see it only goes 1/2 way across the electrode, also some speed shop engine builders "cut" the plugs like that, thought was, it gave a broader spark in the cylinder.....

Thanks. I have several two cycle machines. I'll have to look closer at the plugs; I hadn't noticed. My memory of those plugs came from go-kart days many years ago.

 

[Boobala]

Re: B&S 725ex 190 cc made 3/2013. Engines starts 1st crank, misfires and surges until

Used to race McCulloch powered karts myself .... back in the 60s .. :thumbsup:
her's something you MIGHT enjoy .....

https://www.youtube.com/watch?v=apd1KBjLV8k