What's a good engine idle speed for a small Yanmar "80" diesel engine?

mslisaj · Dec 18, 2017

As I am enjoying my new LS MT125 and all the projects of minor modifications, little fixes and just making the tractor my own. I am curious if the 1350 rpm idle speed is a good speed. I have the factory service manual for this tractor and engine but it does not address engine idle speed or how to adjust it. Just curious what you guys like to see and what other similar engine idle at. This is the simple easy question.

Thanks for taking your time to read my post here and all comments are appreciated.

Regards,

Lisa :thumbsup:

tomplum · Dec 19, 2017

Hmmm Lisa, nearly 80 views and no response yet. That's what you get for calling it a simple easy question! Folks on the XJ with the Mitsubishi talk about avoiding the low idle due to the vibration. I can say on mine if it is in that mood, I bring it up a bit. How is your baby on low end vibration?

Doofy · Dec 19, 2017

Well darn. I would reply if I had an answer but I don't. Sorry.

Katahdin · Dec 19, 2017

It may seem high, but I think the 1350rpm idle is needed to meet the EPA Tier 4 emissions requirements.

California · Dec 19, 2017

Katahdin said:
It may seem high, but I think the 1350rpm idle is needed to meet the EPA Tier 4 emissions requirements.

Wow. Not intended as advice for a modern tractor, but my two elderly Yanmars (sig photo below) in the same hp category idle at half that speed. 1350 rpm feels right for casual put-putting around, or running the backhoe.

thepumpguysc · Dec 19, 2017

That engine has a Yanmar "MP" injection pump on it..
Low idle is set at 800-850 rpms & adjusted at the screw on the injection pump.
Its simple.. Just follow the linkage down to the inj. pump..
1 screw will be capped w/a tamperproof cap & the other is the low idle screw.. its the only screw that can be adjusted..
A 10mm wrench is all you need. Good luck & Happy tractoring.. TPG

mslisaj · Dec 19, 2017

Thank you gentlemen for your responses here. First off at the 1350 the engine does idle smoothly without issues and is high enough to move the tractor and it will operate the attachments. When I was shopping for a Sub Compact I remember watching a video of a gentleman comparing the small Kabota to it's like Manhindra. Both machines were idling but at that speed the Kabota would not move or operate the attachments and the Manhindra would. The point of that demo was to show (this is what the salesman said) that the Manhindra had a better hydraulic pump and could muster up enough pressure and flow at idle while the "weaker" Kabota needed more engine speed.

So I gather here the consensus is 1350rpm sounds a little high and I could lower it as long as the vibrations of the engine didn't get unmanageably. I've scoped out that linkage/idle adjustment screw so I know where I'm headed there. But I also found it very curious that in all the specifications I have for the machine in the owners manual and the shop manual the idle speed is nowhere to be found; not even in the engine sections.

Thanks again genglemen for weighing in on my question. I guess my esoteric questions aren't that simple or no one else has thought about or questioned some of the things I have read in the manuals. I guess I should spend more time in the seat playing with the tractor then reading about it

.

Lisa :thumbsup:

Gary Fowler · Dec 19, 2017

Every diesel engine I have seen idles at around 900 RPM. Gas engines idle about 800-900 also. I don't know why an EPA Tier 4 engine would be any different unless it is in regen mod or something that requires higher. Normal operation should still be within the 800-900 RPM range.

mslisaj · Dec 19, 2017

Thank you Gary Fowler for taking your time to weigh in here. I have found myself reaching for the throttle control trying to slow this engine down as it just "seems" too high an idle. Thus I asked the question. This small engine doesn't have an "regen" or other things wired to it for emissions. I think that's why it's rated at 24.7hp as 25 might be the threshold for all the goodies and DEF to be added. When I get a chance I will throttle it down a little and go from there.

Lisa

jdom84 · Dec 19, 2017

mslisaj said:
As I am enjoying my new LS MT125 and all the projects of minor modifications, little fixes and just making the tractor my own. I am curious if the 1350 rpm idle speed is a good speed. I have the factory service manual for this tractor and engine but it does not address engine idle speed or how to adjust it. Just curious what you guys like to see and what other similar engine idle at. This is the simple easy question.

Thanks for taking your time to read my post here and all comments are appreciated.

Regards,

Lisa :thumbsup:

What are you trying to achieve with the idle? 1350 rpm doesn't seem to high to me. I seen on the forum, someone with the NH Boomer 24 said their tractor was set to idle around 1500 rpm. The NH is the same as the xj2025 with the s3l2 engine made by Mitsubishi but I would think NH set the idle around 1500 because 1000-1300 rpm is pretty rough on these tractors. And like tomplum said, xj2025 owners have been running their tractors higher then the set idle. These small engines are used in more than just tractors and are set to idle at all different speeds, my brother in-law has a generator with a 3 cyl Kubota engine, the thing will run continually at 2000 RPM day after day...

I have also read on the forum, people with the Shibaura engine saying how smooth it runs but not sure what the idle is set at. I'm sure LS set the idle at 1350 rpm on the Yanmar 80 for a reason...