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

Boudreaux In Eunice La. · Apr 20, 2018

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

Where you at Sp 80 within 50 miles ??

IL engine is right on the 20 gap for the plugs.... When I get one IF I think about I do .25..........

Is your spring intact ??? Is your choke opening all the way about 30 seconds after starting ?? Is the plastic vane obstructed by a dirt dauber nest ???

I see that all the time under the air shrouds at my shop ~!~!

sp80 · Apr 21, 2018

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

Boudreaux In Eunice La. said:
Where you at Sp 80 within 50 miles ??

IL engine is right on the 20 gap for the plugs.... When I get one IF I think about I do .25..........

Is your spring intact ??? Is your choke opening all the way about 30 seconds after starting ?? Is the plastic vane obstructed by a dirt dauber nest ???

I see that all the time under the air shrouds at my shop ~!~!

The spring appears to be good. The vane is not obstructed and I haven't observed the choke after starting, however the engine starts easily and runs smoothly for about 30 seconds or a little more then runs roughly until warmed up. After warm up it smooths out. If I stop and restart it follows the same pattern.

sp80 · Apr 21, 2018

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

Boudreaux In Eunice La. said:
Where you at Sp 80 within 50 miles ??

IL engine is right on the 20 gap for the plugs.... When I get one IF I think about I do .25..........

Is your spring intact ??? Is your choke opening all the way about 30 seconds after starting ?? Is the plastic vane obstructed by a dirt dauber nest ???

I see that all the time under the air shrouds at my shop ~!~!

I am in Lafayette

sp80 · Apr 21, 2018

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

sp80 said:
I am in Lafayette

I think this may be a common problem with this model. I exchanged the first one for this one. Both had the same issue out of the box. Fortunately the engine does start and runs OK after it warms up. I am somewhat anal about a smooth running engine. Thanks for your responses.

sp80 · Apr 21, 2018

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

ILENGINE said:
Briggs has a few engines both flat head and OHV that require the .020 gap or you risk misfires and hard starting at .030. The problem is the .020 gap plugs like to foul out without any rhyme or reason.

I tried .030 with the original plug and it didn't help. In fact I did get more misfires and surging. That was a Champion RJ19LMC /BS 591868 plug. The same model manufactured before 11/2011 used the .030 gap. I wonder what was changed in the engine.

Thanks.

ILENGINE · Apr 21, 2018

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

sp80 said:
I tried .030 with the original plug and it didn't help. In fact I did get more misfires and surging. That was a Champion RJ19LMC /BS 591868 plug. The same model manufactured before 11/2011 used the .030 gap. I wonder what was changed in the engine.

Thanks.

If I remember correctly it was due to a change in the ignition module to meet tier 3 emissions standards.

sp80 · Apr 21, 2018

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

ILENGINE said:
If I remember correctly it was due to a change in the ignition module to meet tier 3 emissions standards.

Thanks for that response.

Boudreaux In Eunice La. · Apr 21, 2018

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...

cpurvis · Apr 21, 2018

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.

Boudreaux In Eunice La. · Apr 21, 2018

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

cpurvis said:
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.

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 ~!~!

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

More options

Boudreaux In Eunice La.

Lawn Addict

sp80

Member

sp80

Member

sp80

Member

sp80

Member

ILENGINE

Lawn Pro

sp80

Member

Boudreaux In Eunice La.

Lawn Addict

cpurvis

Lawn Addict

Boudreaux In Eunice La.

Lawn Addict

Footer Links 1

Footer Links 2