Throttle control, engine RPM.

Rdrett

Member
Dec 5, 2017
222
8
18
Paris Ky
Hello.
I was wanting to know how everyone operates there throttle when using there tractors.
I have a L2501 HST.
I have never had the throttle wide open yet.

When I operate my lawn mower which is a small garden tractor I start the mower and I immediately open the throttle all the way up and very seldom does the mower run anywhere below full throttle.

When I run my tractor I usually keep the throttle as low as possible for the job I am doing.

I have seen people who start the tractor up and immediately open the throttle up like I do on my mower.

I have never opened the throttle up because the manual says not to run full throttle for the break in period.

Which is harder on the tractor? Wide open or just enough rpm’s to get the job done without stalling the engine?

Also is it okay to run the tractor at full idle for a long period of time?
I usually don’t like to run any engine wide open.

Sorry for this stupid question I was just wondering what everyone else does.
 

Mike9

Active member

Equipment
Kubota B6200
Oct 9, 2015
391
31
28
Ghent, NY
I run my B6200 wide open in the PTO range. That's what the engine was designed to do. I start it and let it warm up at 1k rpm. then I increase to 2.5k rpm. when it's time to work. I bladed off 9" of snow today and needed every bit of power.
 

85Hokie

Moderator
Staff member
Lifetime Member

Equipment
BX-25D ,PTB. Under Armor, '90&'92-B7100HST's, '06 BX1850 FEL
Jul 13, 2013
10,441
2,221
113
Bedford - VA
Hello.
I was wanting to know how everyone operates there throttle when using there tractors.
I have a L2501 HST.
I have never had the throttle wide open yet.

When I operate my lawn mower which is a small garden tractor I start the mower and I immediately open the throttle all the way up and very seldom does the mower run anywhere below full throttle.

When I run my tractor I usually keep the throttle as low as possible for the job I am doing.

I have seen people who start the tractor up and immediately open the throttle up like I do on my mower.

I have never opened the throttle up because the manual says not to run full throttle for the break in period.

Which is harder on the tractor? Wide open or just enough rpm’s to get the job done without stalling the engine?

Also is it okay to run the tractor at full idle for a long period of time?
I usually don’t like to run any engine wide open.

Sorry for this stupid question I was just wondering what everyone else does.
First - no question is stupid.....'specially if you dont know the answer!:D:)

YOU are correct - dont run it hard when new and not broken in......

NOW - lets flip the coin - diesels WANT and NEED to be be worked - wide the hell open? Maybe not.....but all the hydraulic pumps need to run a spec designed my the company that makes them. Running them lower than that, it hurt the machine? maybe not - but the machine needs to get hot - stay hot and run at torque and Hp it is designed for.

NEVER baby the diesel - let go of the thought, "I should only run this ......barely enough to do the job." BAD thought.

You will find those that cut grass at 1800 rpms ......they say and feel that it is enough to do the job.....perhaps they are right - here is the point, the maker of the mower did the math, and that math said that the blades need to spin at "X" rate to cut well, then why cut grass slower than that? The engine is trying to keep up yet, do to the lower rpm, it needs to try to work harder to do so, more stain on it then IF it was running harder! Some diesels actually use a little less fuel at a little higher rpm! I know that sounds crazy....but I have seen numbers to back that up.

Now there are those that cut grass at 3400 rpms - the grass is coming out of the chute 12' ! Is that harmful? NO!

All kubotas are designed to run at a speed that will NOT hurt the engine -they make an upper limit you cannot exceed - you could run it at wide open throttle for the entire life of the machine as long it is taken care of....oil,filters, radiator, etc..... and it will last a long time!

Most machine(large equipment)operators do not pussy-foot around when they use a track-hoe - it is running at a good clip - simply to do the job easier on the engine and all it's parts and save time.

Have I ever dropped the rpm while using the backhoe? O hell yess!!!! I did not want to swing the boom/dipper into the house that I was working very near by. SO yes there are times when slowing it down makes sense - but for the most part, break it in and run it!:)
 

D2Cat

Well-known member
Lifetime Member

Equipment
L305DT, B7100HST, TG1860, TG1860D, L4240
Mar 27, 2014
13,094
4,466
113
40 miles south of Kansas City
I get confused easily.

Rdrett you say, "When I operate my lawn mower which is a small garden tractor I start the mower and I immediately open the throttle all the way up and very seldom does the mower run anywhere below full throttle."

Same post it says, "... I usually don’t like to run any engine wide open."

Am I missing something, can you clarify?
 

dirtydeed

Well-known member
Lifetime Member

Equipment
B2650 BH77, U27-4R2, BX23TLBM, box blade, rear blade, flail mower, Stump Grinder
Dec 8, 2017
2,906
3,261
113
Wind Gap, PA
I think for break in it's just best to run them as you normally would. I rarely run wide open (haven't yet with this new machine) and not that often with the old bx23 either (only when necessary). Your machine does not have DPF on it, so I don't see a need to run wide open unless you need the power. My $.02 anyway

I did have an issue with the BX running at near idle...the vibration was pretty severe and it kept breaking the air filter brackets...after 3 replacements, I resorted to a bungee cord and it was just as happy.

I have often heard that running them hard (working them) helps seat the rings.
 

JerryMT

Active member

Equipment
Kubota M4500, NH TD95D,Ford 4610
Jun 17, 2017
528
156
43
The Palouse - North Idaho
Hello.
I was wanting to know how everyone operates there throttle when using there tractors.
I have a L2501 HST.
I have never had the throttle wide open yet.

When I operate my lawn mower which is a small garden tractor I start the mower and I immediately open the throttle all the way up and very seldom does the mower run anywhere below full throttle.

When I run my tractor I usually keep the throttle as low as possible for the job I am doing.

I have seen people who start the tractor up and immediately open the throttle up like I do on my mower.

I have never opened the throttle up because the manual says not to run full throttle for the break in period.

Which is harder on the tractor? Wide open or just enough rpm***8217;s to get the job done without stalling the engine?

Also is it okay to run the tractor at full idle for a long period of time?
I usually don***8217;t like to run any engine wide open.

Sorry for this stupid question I was just wondering what everyone else does.
If you want long life out of an engine, an SI engine or a CI engine, you don't take it to max rpm until it reaches operating temperature.

Piston engines need to be run regularly and brought to operating temperature and kept there to "boil off" water condensation and other volatiles in the lube oil and they need to be operated at operating temperatures so that the maximum performance can be obtained as the design clearances will occur in this temperature range.

Commercial operators run "fast and hard" because time is money. Most of you folks on these forums are not commercial operators and many of you want long, reliable, and good performance out of your machines. Flogging them at max rpm (read high piston speeds) will only speed up wear. Run them at the rpm you need to make your machine and associated implements perform the way you want them. If you want to run at max speed realize you're taking life out of the components and accept the fact that you'll replace them earlier than necessary.

Long periods of idling are not good for a diesel. The peak gas temperatures are low, combustion is not nearly as complete as it is at part power, it wastes fuel, and you'll have to deal with "diesel slobbers" or "wet stacking". Slobbers and wet stacking are the oily black stuff you see in the exhaust system on machines that run for short periods and never really get worked hard or often. What good reason would anybody have to run at high idle for long periods other than to check out the top setting on a replacement injector pump? Even then you wouldn't run it for long.

Just my $0.02!

P.S. I have never operated a tractor at max rpm because I have never needed to.
 
Last edited:

Rdrett

Member
Dec 5, 2017
222
8
18
Paris Ky
I get confused easily.

Rdrett you say, "When I operate my lawn mower which is a small garden tractor I start the mower and I immediately open the throttle all the way up and very seldom does the mower run anywhere below full throttle."

Same post it says, "... I usually don’t like to run any engine wide open."

Am I missing something, can you clarify?
I forgot to add in my post that my lawn mower is the only engine I run at max rpm’s 99% of its life and that is the reason I asked the question.
That is what got me thinking “maybe I am not operating my tractor properly, maybe I should start the engine and turn the rpm’s all the way up and go to work”.

I have seen other people operating equipment and they start it up and immediately go to max rpm and start working just like I do to my mower and I was confused on which is the correct. Using just enough engine rpm’s to get the job done without stalling or open up the throttle and go to work.

Also I have noticed that the more load you put on the tractor at lower rpm the more the hst will whine. The higher engine rpm and the less I hear the hst whine.
I thought that I might be causing more wear with the low rpm’s.
 

quicktractor

New member

Equipment
Kubota L2501
Jul 27, 2017
22
2
3
Flagstaff
I also have a new (1 yr old) L2501. After driving some diesel vehicles I think that the diesel engines have a sweet spot in the power band where you get the most bang for your buck from the engine. I typically operate where I assume (and have found) that sweet spot is at which is around the PTO RPM. If you do ever crank that L2501 full open, you will be interested (maybe a little disappointed like me) that full open is not very high RPM and not too different than where you run. I think this might be because 1) There is not much advantage in power to run at a high RPM so it is limited &/or 2) maybe because of the mysterious / theoretical "down tuning" of the L2501 to keep it under 25 hp to avoid the need for emission controls. I am happy to hear others more educated thoughts and corrections.
 

kenmac

Member

Equipment
B26 with hyd. thumb and 4 in 1 loader bucket and EA Grapple, but not the wicked
Dec 14, 2015
92
7
8
Pell City, Al.
Air cooled engines such as is in lawn mowers and chain saws, etc. are designed to run WOT in order to properly cool itself. Not so with water cooled engines. Better to not lug any engine, but full throttle is seldom needed. Just my opinion and reasonable common sense.:)