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How hot should my saw get during operation?

Chris Cringle

Chris Cringle

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Yesterday used my MS 271 with 20 inch bar to buck a ~50 foot red oak stem. About 12 inches diameter at the small end, 16” or so at the stump. It was in a great position for bucking. It was a blow down, so the root plate held one end a foot or so off the ground. The other end was laying on a fallen log. So the entire 50+foot stem was off the ground and at a comfortable height. I used some pieces of scrap 4X4 that I had in the truck to keep it off the ground as I bucked it from the thin end back towards the stump. Got 36 rounds.

It was quick work, with the log so well positioned, saw running well, chain pretty sharp. When I was finished, I was surprised at how hot the saw had become. The shroud above the muffler and below the handle was so hot that you could not keep your finger on it if you touched it. I was surprised the plastic wasn’t melting or burning. On the one hand, I don’t think the saw had ever been run that hard. 36 moderate size hardwood cuts cuts one right after the other, The time in between cuts was however many seconds it took me to step a foot or two to the right. After the first few cuts I checked the chain, it was a little bit tight so I loosened it. Another short break 2/3 of the way through for gas and oil. Ambient temp mid 70s.

My question is, how hot should this saw get during heavy operation? Thanks in advance for any comments.
 
MaddBomber

MaddBomber

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I'm not familiar with the 271, does it have a catalytic muffler? If not, it still may run a little cooler with the muffler open up a bit. My little echo had a cat muffler and it ran very hot until I took the cat out.

Sent from my moto g(7) power using Tapatalk
Excellent point! I completely overlooked that. Opening the muffler will definitely help....and give a slight power bump.
 
outdoortype

outdoortype

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Just about all saws run hot during warm weather but the stratos are hotter. I noticed a big difference when touching the cylinder cover during 50 degree days vs 70 degree days. FWIW, I noticed a big difference when I cleaned the air filter. I stopped to refuel and remembered I hadn't cleaned it in a while. I tapped it and then blew it out with compressed air. I went back to work and noticed it wasn't as hot. I guess that the computer was leaning the mixture to compensate for the reduced air flow causing it to run hotter to achieve the same rpm?
Regarding the cat muffler, I ran 2 359's side by side during a hot humid day 85 and measured the external cylinder temp with a Fluke IR thermometer. The saw with the cat muffler ran 40 deg hotter.
 

Okie

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Right about a restricted exhaust causing overheating. I've seen clogged spark arrestors cause overheating.
I've never tested the loaded running temp on a strato type saw.
But: (from experience)

On a regular chainsaw if the jug temp goes over 350F the piston starts swelling and the engine may seize up at 400F.
When testing a regular Stihl for example a 028 and some homies under a heavy full bar load with a sharp chain using a IR therometer I see the temps rise slowly with 30 sec to 1 min or longer cutting to around 325. If the temp is rising fast and starts above 350 it's time to back off and if it gets to 400 it may seize and or it's headed for self destruct. A really lean chainsaw engine will head towards 350 really fast when under a full bar load.
Just doing trimming and not any long heavy full load cuts the saw may last a long time. When one starts seizing in a full bar cut the OP usually thinks the saw is binding or just bogging, he lifts the saw piss rev's and when it picks up speed back into the cut. the piston is usually eating the cylinder.

You might consider getting a IR and let us know what you see?
You can get a good IR now days for around $25-30 free ship and I use such for lots of other uses, such as comparing cylinder temps on Auto's (a weak cylinder is cooler) heat/Air use instant readings. It will check you body temp but I have not tried mine to detect a Covid 19 carrier, YET

Stay Safe
 
ammoaddict

ammoaddict

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Thank you for these replies. Don’t know if my 271’s muffler is catalytic or not. I’ll have to research. What is “opening” a muffler?
There is a muffler mod thread on this site. From mild to wild. It simply means to make the exhaust exit on the muffler larger. It let's the exhaust gases out faster usually resulting in cooler running and a little increased power.

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ammoaddict

ammoaddict

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Yes it can make them louder, depending on how you mod it. I have 2 that I completely removed the baffle and they are fairly loud. I wear ear protection anyway do it doesn't bother me.

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MountainHigh

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And, opening the muffler also makes the noisier. Personally, I would like a saw to be nearly silent.... :)
But, lot's of power.
N
Electric chainsaw :baba:
Likely the norm in the future.

 
outdoortype

outdoortype

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Yes I need to do a more detailed comparison of a strato and non-strato side by side. One thing I do notice on the Huskys/J-red, the clutch side transfer port seems to stay hotter longer than everything but the clutch cover. The flywheel side stays relatively cool due to the flywheel. I always let the saw idle for a minute before shutting off. But even after sitting 5-10 minutes, that clutch side transfer is really hot. I have heard that they route the transfers near the exhaust to heat the incoming charge...
 
outdoortype

outdoortype

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To the original poster, my Cat muffler 359 only got to 290 deg, but that was only a few cuts in about 5 to 10 minutes. The Cat muffler was a bridge-the-gap type fix to meet EPA regs while the stratos were being developed. I presume that most strato saws meet the regs without the need for a cat muffler. I feel bad for the southern folks that have to run there saws constantly in hot humid weather.
 
Bruiser1

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I also have a MS 271. If you’re under full load and in the cut I believe the instruction manual suggest that you let the saw cool down for a few minutes at idle.Check around the cylinder head for any noodles that might be hampering the cylinder head from cooling down.
I have to admit, I get into a rhythm when I’m Bucking or felling and I forget to check if the noodles build up around the cylinder head Also check the air filter for Sawdust buildup
 
Huskybill

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Ditto make sure the saw is clean around the cylinder fins.

Note, my buddy ran his 55 rancher under half the rpm. He didn’t account the under cooling airflow it caused. I told him more air flow at wot.
 
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