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#4499048 - 08/26/17 11:27 PM Adjusting push mower RPM
CharlieJ Offline


Registered: 06/12/07
Posts: 1423
Loc: FL
Has anyone increased their push/self propelled mower's engine RPM? From reading online, it seems like 21 inch blade mowers are limited to around 3000 RPM for "safety" reasons. Some say that raising the RPM to 3600 is a more ideal running speed for mowers to properly mulch grass clippings.

Has anyone adjusted the RPM of their small engine mowers? I am considering trying it myself.
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#4499052 - 08/26/17 11:42 PM Re: Adjusting push mower RPM [Re: CharlieJ]
Seventh Offline


Registered: 11/11/12
Posts: 234
Loc: NorCal
I've done it on mine. It's a briggs 158cc I believe. It has the plastic primer bulb type carb with no adjustments whatsoever.

The throttle butterfly is attached to a little lever/arm thing on top of the carb. The lever has a spring that goes to the tank mounting bracket.

I pulled the end of the spring through the bracket, one additional "loop" around. Essentially making it pull more on the butterfly.

Picked the revs up nicely, although I have no idea what the actual rpm is... runs way smoother

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#4499055 - 08/26/17 11:50 PM Re: Adjusting push mower RPM [Re: CharlieJ]
gpguy Offline


Registered: 09/19/14
Posts: 14
Loc: Grande Prairie, Alberta,Canada
Ive done it too on my Husqvarna with a Honda GC160 motor.
I thought the mower seemed to lack umphh. Handheld tach showed only 2800 rpm. Max for motor is 3600 but I only adjusted it up to 3200. It made a huge difference in mulching and ability to cut taller grass.
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#4499058 - 08/26/17 11:51 PM Re: Adjusting push mower RPM [Re: CharlieJ]
Merkava_4 Offline


Registered: 01/30/07
Posts: 17501
Loc: Clovis, CA
I do it all the time. I don't have a tachometer, so I adjust the RPM to what I think sounds good.

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#4499115 - 08/27/17 02:42 AM Re: Adjusting push mower RPM [Re: CharlieJ]
Reddy45 Offline


Registered: 08/15/08
Posts: 2973
Loc: USA
I have the RPMs on my Toro Recycler w/ Tecumseh engine maxed out. Since the wheels are belt driven, this also speeds up how quickly the mower moves.

But now I am left wondering if there is an ideal speed that maximizes mulching capability along with propel speed.

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#4499200 - 08/27/17 07:49 AM Re: Adjusting push mower RPM [Re: CharlieJ]
kc8adu Offline


Registered: 08/02/05
Posts: 894
Loc: dayton oh
most ope engines are optimized for 3600 rpm.
but a blade rpm limit is something i would not exceed.
a failure would not be pretty.

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#4499233 - 08/27/17 08:40 AM Re: Adjusting push mower RPM [Re: CharlieJ]
justintendo Offline


Registered: 03/04/17
Posts: 102
Loc: northwest pa
my husky has a honda gcv 190..cant remember for sure what the stock rpm was but it was well under 3k. it lives at 3250 now and handles the grass much better. there is a small uptick in fuel consumption..
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#4499258 - 08/27/17 09:11 AM Re: Adjusting push mower RPM [Re: CharlieJ]
Cujet Offline


Registered: 02/15/03
Posts: 7164
Loc: Jupiter, Florida
I like adjusting for 3600RPM. I don't always use that much RPM, but at times it's helpful.

However, my current Honda 190 will not adjust up that high. It's limited to around 3000 at max adjustment.
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#4499319 - 08/27/17 10:12 AM Re: Adjusting push mower RPM [Re: CharlieJ]
92saturnsl2 Offline


Registered: 03/02/04
Posts: 1282
Loc: Flaherty, KY
I have a 2010-ish Troy-Bilt non-self propelled push mower w/ a Honda GCV160 engine. My governor works off a spring attached to a metal arm- if you raise the spring pressure it raises RPM and vice versa. I took a dremel and made indents in the metal arm, so I could connect the spring to different points on it, ultimately changing the spring pressure that whatever it's connected to sees. Works great, I have about 5 positions all the way from near idle, to full-out screaming (probably dangerous) for when I'm cutting through knee high grass / brush. I've run it at the highest setting a few times when I'm in a real hurry, and it's a beast. Engine doesn't seem to mind what settings it's at. I had some governor surging when I lived in Colorado (high elevation), but that cleared up once I brought it back down to sea level, which is where I bought it. Not sure if that had to do with me monkeying with it, but it's fine now.
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#4499357 - 08/27/17 10:53 AM Re: Adjusting push mower RPM [Re: CharlieJ]
SirWired Offline


Registered: 11/12/13
Posts: 14
Loc: North Carolina
As far as safety goes, at the factory-set RPM, the mower is tested to see if the blade will break through or ricochet out of the deck if it were to fracture, in case anybody was wondering. While the engine has a specific top speed available, it's not for no reason that the manufacturer set the governor at a particular speed in the factory.

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#4500224 - 08/28/17 10:13 AM Re: Adjusting push mower RPM [Re: CharlieJ]
andyd Offline


Registered: 09/25/04
Posts: 7158
Loc: Marshfield , MA
By regulation the max safe RPM is 3200. IIRC
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#4500436 - 08/28/17 02:05 PM Re: Adjusting push mower RPM [Re: CharlieJ]
jeepman3071 Offline


Registered: 04/15/10
Posts: 4220
Loc: Storrs, Connecticut
I usually set them at 3000-3200 RPM. That seems to be the best range for power while still maintaining fuel efficiency. I've seen some Briggs set at 2000-2100 RPM from the factory, basically idling.
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#4502114 - 08/30/17 09:07 AM Re: Adjusting push mower RPM [Re: SirWired]
artbuc Offline


Registered: 12/02/05
Posts: 1165
Loc: West Chester, PA
Originally Posted By: SirWired
As far as safety goes, at the factory-set RPM, the mower is tested to see if the blade will break through or ricochet out of the deck if it were to fracture, in case anybody was wondering. While the engine has a specific top speed available, it's not for no reason that the manufacturer set the governor at a particular speed in the factory.


On my Honda HRS 216 with GVC 160 engine, manual warns that "blade could fracture and come apart" if operated at higher than maximum governed speed of 3000 + 0 / - 150. Mine came from factory dead on 3000. There is a second hole in governor arm which operates at 3350. I wonder how much safety factor Honda builds in? I am guessing the chances of my blade self-destructing at 3350 are pretty minimal.

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#4502991 - 08/31/17 06:06 AM Re: Adjusting push mower RPM [Re: CharlieJ]
CharlieJ Offline


Registered: 06/12/07
Posts: 1423
Loc: FL
I bought one of those small engine tachometers off of ebay for about $10. I have a B&S 550E engine which I bent the metal governing tab to increase the RPM of the mower to 3600 RPM. I have not had a chance to cut grass with it yet, I hope it does a better job.

Anyone know how high these engines will rev? I don't want to take the chance of over revving the engine, but I know it will go 4200 RPM.
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#4503265 - 08/31/17 11:38 AM Re: Adjusting push mower RPM [Re: CharlieJ]
dwendt44 Offline


Registered: 05/17/06
Posts: 3971
Loc: Central Wisconsin
Small engines like B&S aren't designed for high rpm, so I'd be surprised
if they will rev past 5000. If they do, it won't be for long.
Some of these small engines have plastic camshafts and/or gears, and they can't
take the higher revs.
Stick with the 3600 rpm, which is what they are rated at and designed to
hopefully last.
As it is, since most are limited to even less than the 3600, it explains why
they last nearly forever.

My 2
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