Brand-new MX4800 - not happy with power output

troverman

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MX6000 HSTC; 2020 Kubota Z421KW-54 zero turn mower
Jun 9, 2015
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I bought a brand new MX4800 HST a few weeks ago and yesterday mowed a field with a 6-foot flail mower. It was the first "actual" use of the tractor besides moving it around my yard.

In short, I feel like this tractor bogs down easily in heavy, tall grass...especially uphill...even when moving at a creep speed. Before people say I should have bought the MX5200 or 5800, keep in mind I'm comparing this performance against my 2002 Kubota L4310 GST running the exact same mower. The 4310 has 1.5HP less at the PTO and about 4HP less overall. I mowed in low range the whole time with the MX4800; I usually mowed in gear 3 in the L4310...occasionally gear 4...and occasionally had to drop to gear 2 for extremely tall or heavy grass.

I'm also surprised that even at wide open throttle in high range the engine will bog with heavy HST pedal pushing traveling uphill on a road with the PTO off and mower raised.

That aside, the new machine is very smooth...a bit quieter than the 4310...and no diesel smell, which was nice. No headache after 5 hours in the saddle. I'd say fuel consumption is much heavier than in the 4310 as well...full tank to near empty after 5 hours. I could run longer than that mowing with the 4310, and it's tank is 3.5 gallons less.
 

rjcorazza

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L4060 HSTC Loader, ZD326, ZD1211
Mar 9, 2016
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I can’t comment on the flail comparison, however, I can say that my past 2 hst tractors on the road would struggle on hills. Keep in mind that the hst pedal is really a transmission range pedal.


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troverman

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Jun 9, 2015
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Yes, I know. I also have a 2013 B2920 HST and it seems the performance from that HST is more "predictable." This MX has the hydraulic servo foot pedal which does make pedal input very easy but harder to have the "feel" of how much power you are asking for.
 

BAP

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You should talk to the dealer and see if they will put the tractor on a Dyno to see if the tractor is making the rated horsepower.
 

troverman

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Well, you and I use the same dealer and I'm quite certain they don't have a dyno...

Maybe because the engine is new and not broken in it will gradually make a bit more power as things wear in.
 

majorwager

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MX5100 FEL ford 1620 FEL International 484 FEL Lull 844C
I have a MX and fuel economy does improve when moving past the 200 hr mark.

I had a woods 6 ft flail mower behind my 50 hp IH gear tractor, results were dismal.

If OP has success behind a smaller tractor, that is not typical.

There has been much discussion concerning the flail style consumption of hp on the T-B-N website and the two sides will go to war over their opinion.

My position is based upon experience and a flail cut surpasses a rotary in results but the hp drain is excessive.

I do my field mowing w/ a 9 ft - 2 inch befco finish mower w/ 6 swinging blades, and the tractor never hesitates at max med range. Mower is designed for 8 mph. Fields are grass only, no obstacles.

Not hating on flails, just don't quickly blame the tractor for a designed hp thirst this mower style demands.

Many municipal roadside mowers are now flail style, in my area, NONE are attached to little tractors, Local DPW is using a new 110 hp, 6000 M series deere.

Woods may not still offer 6 ft flail, never photographed mine, this is web photo.
 

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BAP

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Well, you and I use the same dealer and I'm quite certain they don't have a dyno...

Maybe because the engine is new and not broken in it will gradually make a bit more power as things wear in.
Actually, I am pretty sure they do. I could be wrong, but I am pretty I have seen one in their shop.
 

BAP

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Well, you and I use the same dealer and I'm quite certain they don't have a dyno...

Maybe because the engine is new and not broken in it will gradually make a bit more power as things wear in.
Actually, I am pretty sure they do. I could be wrong, but I am pretty sure I have seen one in their shop.
 

troverman

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Actually, I am pretty sure they do. I could be wrong, but I am pretty sure I have seen one in their shop.
Hmm...I was in their shop recently. Interesting...I can ask.

Thanks BAP.
 

troverman

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MX6000 HSTC; 2020 Kubota Z421KW-54 zero turn mower
Jun 9, 2015
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I have a MX and fuel economy does improve when moving past the 200 hr mark.

I had a woods 6 ft flail mower behind my 50 hp IH gear tractor, results were dismal.

If OP has success behind a smaller tractor, that is not typical.

There has been much discussion concerning the flail style consumption of hp on the T-B-N website and the two sides will go to war over their opinion.

My position is based upon experience and a flail cut surpasses a rotary in results but the hp drain is excessive.

I do my field mowing w/ a 9 ft - 2 inch befco finish mower w/ 6 swinging blades, and the tractor never hesitates at max med range. Mower is designed for 8 mph. Fields are grass only, no obstacles.

Not hating on flails, just don't quickly blame the tractor for a designed hp thirst this mower style demands.

Many municipal roadside mowers are now flail style, in my area, NONE are attached to little tractors, Local DPW is using a new 110 hp, 6000 M series deere.

Woods may not still offer 6 ft flail, never photographed mine, this is web photo.
This particular field was not mowed last year at all, and obviously its mid July now. The grass is tall and thick. That might be part of my problem. I've never mowed this field my my old L4310. However, in a couple of months I'll be mowing 4 properties that I just mowed last month with the L4310, same mower. That will be the true test.

I can definitely see where a flail is a HP drain...its trying to process a lot more material than a bush hog...but the cut results are very nice, in my opinion.
 

SDT

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multiple and various
Apr 15, 2018
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I bought a brand new MX4800 HST a few weeks ago and yesterday mowed a field with a 6-foot flail mower. It was the first "actual" use of the tractor besides moving it around my yard.

In short, I feel like this tractor bogs down easily in heavy, tall grass...especially uphill...even when moving at a creep speed. Before people say I should have bought the MX5200 or 5800, keep in mind I'm comparing this performance against my 2002 Kubota L4310 GST running the exact same mower. The 4310 has 1.5HP less at the PTO and about 4HP less overall. I mowed in low range the whole time with the MX4800; I usually mowed in gear 3 in the L4310...occasionally gear 4...and occasionally had to drop to gear 2 for extremely tall or heavy grass.

I'm also surprised that even at wide open throttle in high range the engine will bog with heavy HST pedal pushing traveling uphill on a road with the PTO off and mower raised.

That aside, the new machine is very smooth...a bit quieter than the 4310...and no diesel smell, which was nice. No headache after 5 hours in the saddle. I'd say fuel consumption is much heavier than in the 4310 as well...full tank to near empty after 5 hours. I could run longer than that mowing with the 4310, and it's tank is 3.5 gallons less.
Hydrostat transmissions are wonderful to drive but much less efficient than gear type transmissions. Moreover, flail mowers suck HP.

Sounds like you're asking too much.

Yes, hydrostatic transmissions use considerably more fuel than do gear type transmissions doing the same work.

SDT
 

troverman

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MX6000 HSTC; 2020 Kubota Z421KW-54 zero turn mower
Jun 9, 2015
1,188
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NH
Hydrostat transmissions are wonderful to drive but much less efficient than gear type transmissions. Moreover, flail mowers suck HP.

Sounds like you're asking too much.

Yes, hydrostatic transmissions use considerably more fuel than do gear type transmissions doing the same work.

SDT
I'm having a hard time believing this. Rated PTO horsepower reveals how much the HST uses. The difference between a gear drive MX4800 and my HST is 1.5 PTO HP. Nevertheless, this HST tractor still makes 1.5 PTO HP *more* than my L4310 GST.

Heck, my 29HP B-series (HST) runs a 4-foot flail quite well.
 

BAP

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Troverman I sent you a PM.
 

troverman

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Thanks - I don't get PM emails.

I've dealt with Dave in the past and agree - great guy. I need to make sure this issue is not in my head before I bother those guys though.
 

SDT

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multiple and various
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I'm having a hard time believing this. Rated PTO horsepower reveals how much the HST uses. The difference between a gear drive MX4800 and my HST is 1.5 PTO HP. Nevertheless, this HST tractor still makes 1.5 PTO HP *more* than my L4310 GST.

Heck, my 29HP B-series (HST) runs a 4-foot flail quite well.
PTO HP operates your mower.

Drawbar HP moves your tractor.

You do not get both at the same time.

Drawbar HP is significantly lower for a hydrostat tractor than a gear driven model, all else being equal.

SDT
 

FLTRAC

New member
Feb 20, 2018
9
1
0
FL
I have a new 4060 and it almost comes to a complete stop with stall guard and a bush hog 84” finish mower. The mower is near max height cutting bahai not even a foot tall.
 

troverman

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MX6000 HSTC; 2020 Kubota Z421KW-54 zero turn mower
Jun 9, 2015
1,188
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NH
In addition to the power output, my brand-new tractor would not start yesterday! Sat fiddling with the key for about 10 min, moving all the levers to make sure everything was in neutral. Gauges swipe, warning lights come on, no crank. I'm sure a safety switch is failing somewhere...

Plus, the temp gauge got up to about 3/4...well out of the red zone...and anti-freeze was already blowing out of the overflow tank hose. I cleaned the radiator screen, but come on! My other two Kubotas will allow the temp to basically nudge the red zone of the gauge without losing coolant. I guess it's hotter than the gauge indicates. Tractor only has 8 hours on it at this point...

I'd like to try to finish mowing today, we'll see if my brand new Kubota is reliable enough to make that happen.
 

sheepfarmer

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I have a new 4060 and it almost comes to a complete stop with stall guard and a bush hog 84” finish mower. The mower is near max height cutting bahai not even a foot tall.
The maximum width rotary mower that Kubota recommends for the L4060 is 72". That said how are you running the tractor? Should not be in auto throttle for pto work. You should be at a complete stop, engage pto at idle, spin it up to 540rpm, then proceed. I use M gear plus turtle for most mowing but my ground is really rough pasture.
 

Mister

Member
Jul 13, 2018
130
1
18
Northwest
In addition to the power output, my brand-new tractor would not start yesterday! Sat fiddling with the key for about 10 min, moving all the levers to make sure everything was in neutral. Gauges swipe, warning lights come on, no crank. I'm sure a safety switch is failing somewhere...

Plus, the temp gauge got up to about 3/4...well out of the red zone...and anti-freeze was already blowing out of the overflow tank hose. I cleaned the radiator screen, but come on! My other two Kubotas will allow the temp to basically nudge the red zone of the gauge without losing coolant. I guess it's hotter than the gauge indicates. Tractor only has 8 hours on it at this point...

I'd like to try to finish mowing today, we'll see if my brand new Kubota is reliable enough to make that happen.
It's probably your HST pedal. The tractor thinks that your foot is on the pedal, so the safety switch comes on and won't let it start. Jiggle the HST pedal gently forward and back and try to get it to set in to that neutral spot, and then try the key again, making sure you're doing everything else properly for the start procedure

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FLTRAC

New member
Feb 20, 2018
9
1
0
FL
The maximum width rotary mower that Kubota recommends for the L4060 is 72". That said how are you running the tractor? Should not be in auto throttle for pto work. You should be at a complete stop, engage pto at idle, spin it up to 540rpm, then proceed. I use M gear plus turtle for most mowing but my ground is really rough pasture.
I researched and everything was saying you could run a bigger finish mower compared to the rotary cutter. Running in m with stall guard and 540 on the tach goes about 3 mph with the stall guard bringing glme to a stop sometimes. I may need to sell and get a 5’ rotary to mow horse pasture