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Discussion Starter #1 (Edited)
Roughly 3 weeks ago I purchased a gently used X758 with 42.9 hours. So far extremely happy with it. :good2: Have 56 hours on it now.:bigthumb:

My question is operational RPM. On the dash is a "green zone" where the mower deck should be operated. The first few times out I was running at Max and found what I considered high fuel consumption and objectionable noise. Plus it just seemed like it was revving way more than it should.

The Mini Max motor already runs much high RPM than the Yanmar in my JD 2305 which I routinely run at 2,500 RPM for general mowing and 2,00-2,200 for spraying. Fuel consumption on the JD 2305 is 3 quarts per RPM corrected hour.

So................the last couple mowings I have backed the throttle down to one bar under the "green zone", cut is acceptable and the tone of the motor sounds more reasonable.

What say Ye veterans of the mini max? :drinks:
 

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Depends on what I am doing. For mowing I typically run WOT because the tip speed of the blades is as high as it will get. That increases cutting performance for me.

For tilling I typically run the tractor at 3/4 throttle or so. I don't like running the tiller wide out in ground I don't know, at lower rpms the tiller seems to bounce off rocks more instead of ingesting them.

Snowblowing is a mix, if its wet and heavy I run it wide out. If its lighter I will use less throttle.

I don't find the sound or rpms offensive. The deck is louder than the tractor most of the time IMO.
 

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Discussion Starter #3
Well I am now up to 56 hours. I am keeping track of how far 10 gallons go, and it seems that running less RPM is helping fuel consumption. The lower RPM sounds better and cut quality is just fine.

The mini max motor is noisier than the older Yanmar in the JD 2305.
 

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Roughly 3 weeks ago I purchased a gently used X758 with 42.9 hours. So far extremely happy with it. :good2: Have 56 hours on it now.:bigthumb:

The Mini Max motor already runs much high RPM than the Yanmar in my JD 2305 which I routinely run at 2,500 RPM for general mowing and 2,00-2,200 for spraying. Fuel consumption on the JD 2305 is 3 quarts per RPM corrected hour.

So................the last couple mowings I have backed the throttle down to one bar under the "green zone", cut is acceptable and the tone of the motor sounds more reasonable.

What say Ye veterans of the mini max? :drinks:
What is a Mini Max? The X758 has a 3-CYL Yanmar diesel just like your 2305 but 107cc smaller.
 

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What is a Mini Max? The X758 has a 3-CYL Yanmar diesel just like your 2305 but 107cc smaller.
Yeah, I've never heard that term before. Whether the diesel in the x758 runs at a different RPM than the older 2-series, I don't know.

I always run my x758 at WOT when mowing. I get 0.8-0.9 gal/hr while mowing and I almost always am mowing pretty tall grass. The '3 quarts per hour' is, I assume, 0.75 gal/hr so that really isn't significant to me. I can mow my 7 acres in 4.5 hours and not have to fill the tank during that run so I'm happy.

I snowblow at WOT too. Never really tried at lower RPMs so I know know whether it makes much difference.

Definitely agree that the x758 is loud at WOT, especially when running the mower. I wear noise cancelling headphones to reduce that noise and to listen to music. My Bose QuietComfort 35ii headphones work great for that.

Rob
 

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Discussion Starter #6
What is a Mini Max? The X758 has a 3-CYL Yanmar diesel just like your 2305 but 107cc smaller.
The new mini max motors are smaller and run 3,600 rpm @ WOT.

Yanmar MiniMax Diesel Engine - Lawn Landscape

The Tuff Torq K90 tranny was designed for 3,200

K92 - Tuff Torq Corporation


This is why I haven't been running at WOT besides the obvious noise and it just seems like it is over revving. IMHO, every machine has a tone at which seems like is the "sweet spot". WOT doesn't seem like it to me.:banghead:
 

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Discussion Starter #7
What is a Mini Max? The X758 has a 3-CYL Yanmar diesel just like your 2305 but 107cc smaller.
I feel there are pretty significant differences between the the 3TNM74 motor (X758) and the 3TNV76 in the JD2305. The latter makes great power at 2,000 and 2,200. For mowing 2,500 is quiet and you could talk above the motor at that speed.

The only reason the Mini Max exists is for EPA Tier 4 emission compliance.
 

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If a 2 series is designed for 2500 rpm, then it’s pto is set to change 2500 to 2000 rpm output.

An x7 is setup for 3450rpm engine speed creating 2000 rpm output.


A generic k92 might be set for a 3200 input, but JD orders them built to spec that changes WOT to 2000rpm pto speed. For the x7 series that’s 3450.


Yes lower rpm saves fuel, but at the price of performance. If saving a dollar was that important, then an x7 is a horrible choice. You could have saved thousands and got a simplicity.
 

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The new mini max motors are smaller and run 3,600 rpm @ WOT.

Yanmar MiniMax Diesel Engine - Lawn Landscape

The Tuff Torq K90 tranny was designed for 3,200

K92 - Tuff Torq Corporation


This is why I haven't been running at WOT besides the obvious noise and it just seems like it is over revving. IMHO, every machine has a tone at which seems like is the "sweet spot". WOT doesn't seem like it to me.:banghead:
Thank you for the info. I had not heard the term MiniMax before.
 

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Discussion Starter #10
If a 2 series is designed for 2500 rpm, then it’s pto is set to change 2500 to 2000 rpm output.

Correct PTO speed for the 2 series is 2,900 RPM, what I said is it runs good at 2,500

An x7 is setup for 3450rpm engine speed creating 2000 rpm output.

The manufacturer Yanmar says it runs 3,600


A generic k92 might be set for a 3200 input, but JD orders them built to spec that changes WOT to 2000rpm pto speed. For the x7 series that’s 3450.

Do you have a link to verify that?


Yes lower rpm saves fuel, but at the price of performance. If saving a dollar was that important, then an x7 is a horrible choice. You could have saved thousands and got a simplicity.
I bought the X758 because it amuses me and so I wouldn't have to take the 3 point sprayer off the JD2305 weekly as it has been relegated to orchard duty. BTW, I have a Simplicity Conquest with a turbo bagger, cut is outstanding. This machine with under 100 hours and the bagger was cheaper than John Deere wanted for the bagger on the JD2305.

My beef is the EPA creating onerous regulations on diesels. Don't even let me get started on the new auto tune computer controlled chainsaws. In January I bought a NIB Husky 395XP and threw it on the shelf because that saw which has absolute perfect timing numbers is about to be discontinued here. The other ones already discontinued, 346Xp, 357XP, 288XP are still be made in others countries. You can't get them here because the world will end as we know it when a firewood hack like me burns a few gallons of 2 stroke fuel
 

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