B2650 RPMs during start up, operation, and shutdown

Clover13

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Jul 27, 2018
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My B2650 stays in my unheated garage.

When I start it in cold weather, I do not move the throttle up before starting.
But, it will have a higher idle when it starts.
So, the manual states to set the idle manually, but the tractor is programmed to raise the idle.

My B3200 did the same.


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That's interesting. Mine idles around 1050 when started/cold (50-60 degrees outside) and then idles around 1100-1200 when I'm done and letting it cool down before shutting it off.
 

beckmurph

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Equipment
Kubota LX2610TLB/Woods finish mower/woods rotary cutter/
Aug 23, 2012
307
259
63
catlettsburg, ky
That's interesting. Mine idles around 1050 when started/cold (50-60 degrees outside) and then idles around 1100-1200 when I'm done and letting it cool down before shutting it off.


Unheated. 10-15* Fahrenheit.


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eipo

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L4060
Dec 1, 2015
693
83
28
MI
I'm fairly certain the 2650 fuel pump is not controlled by a computer.

Mine sits in an unheated barn. Cold idle even below 0 is 1050-1100. The only thing that will increase idle short of some type of malfunction is operator input.
 

SidecarFlip

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M9000HDCC3, M9000HD, Kubota GS850 Sidekick
Oct 28, 2018
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USA
I always start my M series at idle and after a minute or two, bump them up to slightly above base idle to allow them to warm up (needle on the temp gauge is moving off cold) and stabilize internal temperature no matter what the ambient temps are. I keep both in an unheated barn and it gets downright cold in the winter here in Michigan.

I also add Power Service to the fuel tanks in the winter to prevent gelling of the No. 2 diesel and I never run bio-diesel. Had a bad experience with bio and algae a few years back with my farm truck that cost me a lot of money in replacement parts. No bio on this farm anymore.

Always make sure the starting battery is in good shape and fully charged too.
 

troverman

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MX6000 HSTC; 2020 Kubota Z421KW-54 zero turn mower
Jun 9, 2015
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The discrepancy between half throttle and idle warmups is the DPF. Idling fills the DPF faster than any other RPM; full throttle fills it the least. Kubota picked the mid point between too much engine wear when cold and too much filling of the DPF.

The B-series (aside from the 3350) all use indirect, mechanical injection and no computer. They have no DPF, no EGR, no electronic control over the engine at all, other than the starter and electric fuel solenoid to shut it off. They claim "Tier 4 Final compliant," which they are, but the reality is that all diesel engines 26HP and under simply are not emissions controlled.

My 2018 MX4800 says to start the engine with the throttle at 50%. This throttle is 100% electronic. The engine will start at idle and about 1 or 2 seconds later increase the RPM to 50%. I start my 2013 B2920 at idle.

My MX probably saw about 2 hours on the clock at lower RPM before I ran it almost always at wide-open throttle for the next 60 hours which is where it stands now. I don't expect any harm to come to the engine.
 

Stmar

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B2650HSDC
May 23, 2017
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Buffalo, Wyoming
At first I did not pay much attention to this thread, the manual says what the manual says. Then I read a bit deeper in the thread and realized that the manual was for both the 2650 and 3350, non dpf and dpf, so how could it be the gospel? It sounds like the consensus is to start the 2650, non dpf, at idle and the dpf 3350 at 50% because of the filter. in reality the difference between 50% 1250 rpm vs idle 1050 rpm is not that much in the grand scheme of thing.
 

troverman

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MX6000 HSTC; 2020 Kubota Z421KW-54 zero turn mower
Jun 9, 2015
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At first I did not pay much attention to this thread, the manual says what the manual says. Then I read a bit deeper in the thread and realized that the manual was for both the 2650 and 3350, non dpf and dpf, so how could it be the gospel? It sounds like the consensus is to start the 2650, non dpf, at idle and the dpf 3350 at 50% because of the filter. in reality the difference between 50% 1250 rpm vs idle 1050 rpm is not that much in the grand scheme of thing.
When the manual says "half throttle" I'm reading that as sliding the throttle lever to about half-way up it's travel, not half of it's max RPM.

I think realistically it doesn't matter. I start my MX at idle most of the time despite what the manual says. I don't care if it regenerates more often.
 

Clover13

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Jul 27, 2018
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At first I did not pay much attention to this thread, the manual says what the manual says. Then I read a bit deeper in the thread and realized that the manual was for both the 2650 and 3350, non dpf and dpf, so how could it be the gospel? It sounds like the consensus is to start the 2650, non dpf, at idle and the dpf 3350 at 50% because of the filter. in reality the difference between 50% 1250 rpm vs idle 1050 rpm is not that much in the grand scheme of thing.
Ah, OK so I was thinking "half throttle" was pushing the throttle half way in it's range of movement...that would be way higher than 1250 (of the 2500 "max") since the lower range starts at ~1050.
 

Stmar

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B2650HSDC
May 23, 2017
929
47
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Buffalo, Wyoming
We interpret things differently for sure. To me "half throttle" is half the rpms of WOT, which in the B2650 would be about 1250 rpms. Physical position of the throttle lever would not make sense to me because a lever could be different in different machines. I had two 8Ns and the throttle lever position was different for desired rpms. That being said it makes sense that the two machines in the B manual would have different desired operation procedures; idle for the 2650 and half throttle, more rpms, for the 3350, at start up. I went by the manual but may alter now.
Got a skiff of snow today but not enough to plow, have the chains on and full tank of winter treated fuel so ready to go.
 

troverman

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MX6000 HSTC; 2020 Kubota Z421KW-54 zero turn mower
Jun 9, 2015
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We interpret things differently for sure. To me "half throttle" is half the rpms of WOT, which in the B2650 would be about 1250 rpms. Physical position of the throttle lever would not make sense to me because a lever could be different in different machines. I had two 8Ns and the throttle lever position was different for desired rpms. That being said it makes sense that the two machines in the B manual would have different desired operation procedures; idle for the 2650 and half throttle, more rpms, for the 3350, at start up. I went by the manual but may alter now.
Got a skiff of snow today but not enough to plow, have the chains on and full tank of winter treated fuel so ready to go.
Well, the owner's manual says "set the throttle to halfway" (how would you know the exact position for exactly half of max RPM?) so I assume it is position rather than an exact RPM.
 

tiktock

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Jun 27, 2018
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Plaistow
I assumed "half way" was worded that way because before the machine is on, there's no way for them to say "set it to X RPM" as the needle only displays once the engine is running. Thus the only measurement you have is the range of the lever...so I put it "about half way" through its range of travel to start my BX tractor. No idea if this is correct.
 

Freeheeler

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b2650 tlb
Aug 16, 2018
706
523
93
Knoxville, TN
If zero throttle is idle, lets say 1000rpm, and full throttle is 2500, then either way you look at it, half throttle would be about 1750. I don't care what it says in the manual, I'll continue to do what I've always done. This tractor will probable outlive me no matter how I treat her ;)
 

Clover13

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Jul 27, 2018
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NJ
We interpret things differently for sure. To me "half throttle" is half the rpms of WOT, which in the B2650 would be about 1250 rpms. Physical position of the throttle lever would not make sense to me because a lever could be different in different machines. I had two 8Ns and the throttle lever position was different for desired rpms. That being said it makes sense that the two machines in the B manual would have different desired operation procedures; idle for the 2650 and half throttle, more rpms, for the 3350, at start up. I went by the manual but may alter now.
Got a skiff of snow today but not enough to plow, have the chains on and full tank of winter treated fuel so ready to go.
Thinking about this more...the manual says to set the throttle BEFORE you start it. Not sure how you'd know where the "RPM half" is unless you marked it somehow on your tractor or have a good idea of where that would be. The "position half" is easier to determine because you can turn the throttle handle the whole way and get it roughly in the middle before you start the tractor.

Either way, that part of the literature is confusing as heck...I'm good with just idling mine at the lowest throttle setting :)

EDIT: What Freeheeler said...except I go with lowest throttle to start instead of half :)
 

sheepfarmer

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Nov 14, 2014
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As mentioned before, the only way I could get any kind of non dead idle starting rpm is to choose it and place the throttle there just before shutting it off the last time I use it. So I set it as a compromise of all the confusing directions around 1200 rpm and shut it down.
 

RCW

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BX2360, FEL, MMM, BX2750D snowblower. 1953 Minneapolis Moline ZAU
Apr 28, 2013
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Debating the intention of the manual is a challenge, unless you wrote it. Comes down to opinions.
I lean toward half-throttle being half-rated WOT RPM. Seems more objective than half-travel.
JMHO ......


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