Adjusting push mower RPM

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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.
 
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
 
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.
 
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.
 
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.
 
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..
 
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.
 
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.
 
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.
 
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.
 
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.
 
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.
 
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¢
 
Originally Posted By: artbuc
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.


Increasing blade speed to 3350 made a huge difference in quality of cut. I have been very disappointed in how this mower cut. Ditched mulching and sharpened blade without much improvement. Hope I am right about th safety issue. I can't believe this mower is safe to operate at 3150 but will self-destruct at 3350. Why would Honda have a second hole in the governor arm with no warning label on the mower deck saying " DO NOT USE THIS HOLE. MOWER WILL EXPLODE!!!"
 
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Originally Posted By: artbuc
Originally Posted By: artbuc
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.


Increasing blade speed to 3350 made a huge difference in quality of cut. I have been very disappointed in how this mower cut. Ditched mulching and sharpened blade without much improvement. Hope I am right about th safety issue. I can't believe this mower is safe to operate at 3150 but will self-destruct at 3350. Why would Honda have a second hole in the governor arm with no warning label on the mower deck saying " DO NOT USE THIS HOLE. MOWER WILL EXPLODE!!!"


I doubt the mower will explode at 3350 RPM, and it should be safe to use that hole on the governor arm. Keep in mind the GCV160 is used on multiple applications, so that is likely why it has a few governor speed options.
 
Yes, I agree that it is economically impractical to carry multiple governor arms for various applications. My point is that Honda would put a big warning label on the engine and/or deck to minimize liability if they really thought using the second hole was a big deal. Just a guess of my part.
 
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I'm sure the government standard has more to do with the speed of objects thrown, than the toughness of the product, lack of a better word. Generators and pressure washer run at 3600rpm.
 
I'm sure the government standard has more to do with the speed of objects thrown, than the toughness of the product, lack of a better word. Generators and pressure washer run at 3600rpm.
 
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