BS Motor rpms

kleinerpiner · May 16, 2017

I have a Wards 42" mower with a 14 hp single cylinder Briggs. Runs fine when blade is engaged, but when it is not, or if it sits without moving, the engine oscillates (speed goes up and down). The governor arm is moving to the same frequency.

Any ideas for a cure?

Thank you.

MNGB · May 16, 2017

What is the Briggs model number, is this a horizontal shaft engine?
GB in MN

old · May 16, 2017

In most cases that is a carb problem and it could be running to rich or to lean. One way to check is try choking it a bit and if that helps then it is running to lean if it hurts then to rich. You also might try pulling the air cleaner off and see if that helps and if it does the air cleaner needs to be cleaned or replaced. And last but not least the gov linkage or butterfly maybe sticking and need to be cleaned and lubed up. Have run into where the butterfly pivots to rust up and then the butterfly sticks so the gov does not work well

kleinerpiner · May 16, 2017

Vertical shaft. Model Series 28E700

MNGB · May 16, 2017

I also think its running lean and it looks like that engine has a fixed main jet so no adjustments, you can try adjusting the idle jet to see if that will help turn it out (CCW) 1/8th of a turn maybe up to 1/4 turn if it helps ok if not turn the idle jet back to where it was and try cleaning the carb good, there maybe a build up of crud in the main jet or anywhere in the carb, Good luck
GB in MN

Texasmark1 · May 16, 2017

My experience with those engines is that they are setup to run with a load. When unloaded the timing is off a little and they hunt and misfire and all that stuff. I don't worry about it if it does it's job under load. Tecumseh engine governors are the ones that gave me fits, mechanical driven, not air pressure driven like BS.

T.R.K. · May 16, 2017

More than 95% of the time that is caused by a partially plugged jet in a carburetor. It is usually in the idle circuit.

That engine can hold its rpm pretty well when everything functions as it should.

jeffcat · May 16, 2017

Another thing with Briggs engines. I have found all five of mine run perfectly with Hi-Test gas. Empty the junk out of 5he tank and fill it with the good stuff. Also throw a little Sea Foam in the tank. Lastly I always use StarTron in my gas. It has enzymes that break down the ethinol. Regular gas is just crap anymore. If your carb has a main jet screw I would tell you to give it a tiny turn open a little. That is CCw.

oldsarge · May 17, 2017

Agree;If it works right under load,don't FIX it!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

guido · May 24, 2017

Hello kleinerpiner,

The idle jet is partially clogged. Clean it and she will purr like a kitten at idle,

Guido.

kleinerpiner · Jun 1, 2017

Update

Changed air filter, no change, but it needed to be replaced anyway. One responder said to pull out choke and if it improves, the mixture is too lean. I pulled the choke out about 1/3 of the way, and it smoothed out real nice. So, how do I make the mixture less lean (more rich)?

Thanks to all previous responders.

MNGB · Jun 1, 2017

So, how do I make the mixture less lean (more rich)? Go back and reread the post there were three (3) hints.
GB in MN

BS Motor rpms

kleinerpiner

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MNGB

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old

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kleinerpiner

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MNGB

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Texasmark1

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T.R.K.

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jeffcat

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oldsarge

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guido

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kleinerpiner

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MNGB

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