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X700 Series mowing RPM

5K views 21 replies 10 participants last post by  MowerDude 
#1 ·
Hi Guys,

OK, here's the question. I know you 'should' only mow at full throttle, especially if you're using an air cooled engine, BUT, since the Yanmar is water cooled, I'm guessing it would be OK to mow light, dry grass (not heavy wet stuff) with a reduced throttle setting. Why? To keep the noise levels down. Now, I'm not talking about lugging the engine at idle, but perhaps 1/2 throttle? It won't overheat, I would not let it bog down. I understand that the blade tip fps will be lower, but I don't think it would affect the cut quality too much.

On the subject of noise, does anyone have any experience on how much a X700 series with diesel running a 54" or larger deck compares with say a smaller air cooled set up like a 100 series or X300 series? I am pretty much convinced that the deck is by far, noiser than the engine even at full tilt, and a dirty deck makes a deafening 'hover craft hum'.

Is a 62" noiser than say a 54" or 48"?

Care to share any comments, experiences on this?

:thanku: in advace.

John
 
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#3 ·
My opinion here is based on my owning and operating a GT235 since 2002 (18hp B&S twin/48C deck), and an X748SE for 2 years (54C deck). I've actually put more hours on the X7 (515) in two years than I have the GT235 (460) in eight.

At full throttle on both, the X7 diesel IS louder than the gas twin when sitting on them, but at 50 feet, you really don't notice the difference. As a neighbor, personally the bigger tractor wouldn't be any more intrusive to me, IMO. For what it is, it's impressively quiet.

As far as not running the diesel WOT in lighter grass, sure, you could do it, and it will probably cut okay as long as the blades are sharp. BUT..... at half throttle, your ground speed is about half what you can do at full throttle, so you've got the pedal on the floor to just cut at a speed that you could easily cut heavier grass at a higher speed than. You also have less available torque when negotiating hills or changing terrain. If the deck is not really clean, the reduced blade speed won't clear the grass as well from the deck, since the deck's design parameters aren't being met as far as vacuum and air velocity goes.

Even when my 54C deck is "dirty", meaning grass packed around the spindle areas and in the dead zone along the front of the deck between the center and left blade, it isn't as loud as the engine by a far cry. The loudest thing on the diesel is the fan. It's between you and the engine, and is pulling air through the screens just in front of you, so the most noticeable noise is air movement.

My 54C deck is no louder than the 48C deck, maybe quieter, because of less belt noise (the 54 is shaft/gearbox driven, one less belt) I couldn't say for sure, but I don't see the 62 being any louder than the 54.

I see no reason not to run the X7 WOT, as recommended. That's how it was designed to be used, and it just works better that way.
 
#8 · (Edited)
...it isn't as loud as the engine by a far cry...
Really? It's the opposite with my LA130. The B&S twin 21hp belts out a good tune, but's lost once the PTO is engaged. The deck roars to life. I would have thought the liquid cooled engines are quieter.

Hmmmmm...
 
#6 ·
For my neighbors? :biglaugh:
 
#9 ·
Cool!
Uh oh, they have a JD Logo = $$$

But I'm more concerned about noise as heard from a neighbor stand point. I'm already deaf (sort of).:)
 
#10 ·
I think it's partly the frequency range the diesel puts out; the engine tone is lower than a gas engine, and it doesn't seem as intrusive. Plus, it's all what part of the orchestra is your favorite to concentrate on when listening to Beethoven. I prefer the strings and percussion (engine) to the brass and woodwinds (deck).

I'm sure an air-cooled diesel would be louder than the liquid-cooled one.
 
#12 ·
EngineTech,

I agree about the fan speed But I do have to ask this... If the engine is making maximum torque at a lower RPM, wouldn't that be more ideal that rolling off the torque? For example this Yanmar makes just shy of 50 Lbs/Ft @2300 RPM, that's it's max torque output, max RPM is 3600 according to the Manufacturer.

I run mine at half throttle lots of times, and the temp gauge is still in the cold, and I don't notice any massive heat buildup in the hydrostat. But I am not mowing the side of a mountain either.
 
#13 ·
...Yanmar makes just shy of 50 Lbs/Ft @2300 RPM...

...the temp gauge is still in the cold, and I don't notice any massive heat buildup in the hydrostat. But I am not mowing the side of a mountain either.
That's true. The high torque @2300 would indicate the engine is running at it's peak volumetric efficiency, thus is producing the most usefull power it can (although at a lower RPM). It will also produce maximum heat at this point, because the cylinder charge can never be higher than this, BUT I don't think it would in anyway overload the cooling system, so it should not be a problem as you said yourself, the temp guage doesn't budge. Also I agree that the resultant fan speed should still be more than adequate to cool the the hydro system, after all it's just mowing, not plowing or yanking a 2000lb trailer up a steep incline for 6 miles.

As I said, "just mowing light, dry grass" and that's on flat terrain.
 
#15 ·
No no, thier not touchy, I don't think anyway, yet...

It's just that I was wondering if this thing was going to be 'extremely' loud or just about the same as any 'ol tractor (like I have now). I had visions in my mind that it'll hum along like a branch chipper...

I had a neighbor whom was building a new house. One Sunday afternoon he had a Bobcat delivered so he could move some soil around. Well it wasn't 20 minutes before the 'thought police' er, sorry... the local municipality came by to shut him down... "Too noisy for a Sunday afternoon..." they said. It was raining for Pete's sake. Everyone else was inside! Go figure. He sent it back. That cost him. Imagine renting a Bobcat for 20 minutes. Ouch!

Just curious
 
#17 ·
I had a neighbor whom was building a new house. One Sunday afternoon he had a Bobcat delivered so he could move some soil around. Well it wasn't 20 minutes before the 'thought police' er, sorry... the local municipality came by to shut him down... "Too noisy for a Sunday afternoon..." they said. It was raining for Pete's sake. Everyone else was inside! Go figure. He sent it back. That cost him. Imagine renting a Bobcat for 20 minutes. Ouch!
Ouch is right!! What happens if you fart too loud!! 30 days in the slammer!!

Seriously, you won't have to worry about being anywheres near as loud as a bobcat! Just another lawn or garden tractor purring along! I bet that some of the Zero-turn lawn service machines would be louder than your new tractor. JMO. :fing32:
 
#18 ·
We ran into the "Noise Police" over in Germany too! I was mowing the yard one Sunday and I was politely asked by the Polizei to stop mowing. Seems it was a normal German Law that you can't do that. When I asked for a list of the "Normal German Laws" they said that they aren't written but everyone knows them. But I didn't mow on Sundays anymore!!!
 
#19 ·
Ow! So , if you're a German, work 5 days a week, it rains on Saturday, you're basically screwed!
Yikes, imagine a month of rainy Saturdays?
 
#21 ·
Mowing and the generator is the only time my 749's are run full throttle, the main reason is I want the higher RPM to shred the grass properly, as for temp I have tried a few different RPM's under load and the guage always reads the same.

As for noise, the deck is the quietest I have seen hands down, I have had many clients shocked at how quiet they are.
 
#22 ·
...I have had many clients shocked at how quiet they are.
That's good to hear (pun fully intended). So based on what I'm hearing, it should be as quiet or quieter than my current setup.

Great.

Thanks.
 
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