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Discussion Starter #1
Hi all,

I inherited a little MTD 20" no frills push mower with a 125cc Briggs a couple years ago. I use it as a trim mower for about 20 minutes at a time after mowing with the Cub.

After using it for the first few weeks and dealing with poor cutting performance, I decided to try tying off off a few coils on the governor before I put it at the curb. Doing this raised the running rpm from about 2800 from the factory to about 3400rpm, greatly improving the performance of the mower. It has performed flawlessly since.

After being cooped up in the house for so long now, I am thinking I might do my first mow or two with the push mower, just to get the blood flowing a little. Should I be concerned about running this mower for a few hours at a time? I have about 1/2 acre to mow and don't want to kill it prematurely.

Any thoughts??
 

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Hi! Not sure about a Briggs however Lawnboys run at 3200 with no issues. Maybe drop it down a little to be safe. Blade tip speed is usually what they go by for safety. Not sure running above 3200 is of any benefit. I am sure someone will be along with the specs on the Briggs, Bill
 

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Discussion Starter #3
Hi! Not sure about a Briggs however Lawnboys run at 3200 with no issues. Maybe drop it down a little to be safe. Blade tip speed is usually what they go by for safety. Not sure running above 3200 is of any benefit. I am sure someone will be along with the specs on the Briggs, Bill
I could probably drop it down fairly easily. I made the change, then did the calculation based on where it came out. I estimate its running a little under 18k ft/min right now with the 20" blade.

I wasn't concerned initially, as I read that most small engines are designed to run at about 3600rpm. However, I started thinking about the fact that this was about a 20% increase over what it was originally set for, and began wondering if maybe there was a reason it was set so low from the factory. Perhaps I am just overthinking things.

Also, FWIW, thinking back on it, I believe that increasing the RPM also eliminated the constant surging that was experienced anytime it was not under load. Not exactly sure what the explanation is for that. I was just happy it was cutting well so I didn't have to go over some areas multiple times.
 

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3400 should be just fine. If it does grenade, weren't you thinking of getting rid of it anyways? Most gas generators run at 3600. It's good you checked the RPM before adjusting to get a baseline of 2800. I'm wondering if that is indeed a "factory spec," though. Maybe someone tinkered with it or it was never set right from the factory, and it's supposed to be running 3200-3400. I don't have a clue what the original spec on that one was.

As was said, don't let it overheat (keep debris out from under the shrouds and out of the fins), and keep the oil checked and changed.
 

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Most of the Briggs small engines from the 1950s to recently could be governed up to 3600 RPM. Some manufacturers change that depending what the engine will be used on and blade size. Roger
 

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Discussion Starter #7
It sounds like I am in safe territory and will be sure to keep the oil topped up. I know I was originally going to scrap it, but we've bonded somewhat over the last year or so now that it cuts and runs well, lol. I'll post a reply in the unlikely event it blows up on me!

Thanks again for all of the replies.
 

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Maybe change the oil to a good quality synthetic for a little added protection?
 
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