MS250 gets hot

[Delirium]

Hey all, this is my first post here. Be nice.
So I've got an MS250 I bought a couple years ago for odd jobs. Last fall I got a small piece of land and this summer the saw has been getting more work. Not a ton, just light clearing and cutting firewood. It always starts up right away and runs fine, but lately I have noticed it gets very hot, very quickly. Like after a few cuts, the muffler is smoking hot and "pinging." I recently took it in to a Stihl dealer for some love. They said they ran it and it didn't seem to overheat on them (not sure if they tried cutting). Told me "yeah, they'll get hot." But I don't think it should be getting this hot. I went out to do some cutting just now and same thing. 3 cuts through a 10" cherry log and it's smoking. Even the top of the plastic body was too hot to touch.
Again, the saw doesn't seem to be underpowered or overworked. The chain is sharp, the bar is getting oil, the saw is clean, the gas is (relatively) fresh. That's about all I know. Any ideas on what it might be? Or are saws really meant to run that hot?
Thanks for your help.
Ben

[joe_indi]

Hi and welcome Ben.

Is the time for cutting  the log taking longer than usual, even with a sharp chain? What chain are you running on your saw.

Joe

[Delirium]

Hi Joe,
No everything else about the saw seems to be fine. It starts up easily every time and never quits, seems to have plenty of power for what I'm doing. I'm not sure of the specs of the chain at the moment but it's whatever came with the saw, on an 18" bar.
One thing that was suggested to me (and sounded promising) was adjusting the carb to run richer. I tried backing out the H screw slightly past the recommended setting, but apparently it's limited to right about the factory setting (3/4 CCW). I'll have to see if whatever adjustment I made helps any.
Thanks

[joe_indi]

18" bar is taking it to the upper limit for a MS250.
If it is a 3/8" pitch you could ease the load by using the 6 teeth chain sprocket of the MS180 # 1123 640 2003. The standard 7 teeth sprocket is # 1123 640 2072.

Joe

[leeper69]

have you cleaned out the saw with compressed air it sounds like a air circulation problem. ie the cooling fins on the cylinder are plugged with cutting fines.
at worst case a new aftermarket 42.5cc motor only runs about fifty dollars us.and a rubber replacement kit with fuel, oil line and filters oil pump sealing o ring and carburetor  intake runs about 10 bucks. also be sure to take off the muffler and clean the spark arrester screen thay will plug up and cause over heating.

[celliott]

Another Vermont member, welcome to the forum!

I'd give it a real good cleaning, the cylinder fins especially.
You can defeat the factory 3\4 turn limiters on the carb to richen the mixture up even more. Depends on what type of limiters they are, some are easy, just trim a plastic tab.
+1 make sure the chain is real sharp, pulling good chips and not dust.

Just a question, are you running the saw at part throttle, or WOT?
It's meant to run at WOT, run it at half, or part throttle, and you don't get the full cooling effects of the flywheel fan and the fuel mixture.
Just saying, I've seen some guys run saws at part throttle before, all the time. Not saying you are, but it's a possible cause of overheating.

[Cornishman]

I dont want to worry you but if you have a weak mixture it will cause your saw to overheat and worse case could result in a cooked piston. This can be carb adjustment but also an air leak would do the same. Check the carb mountings  for tightness and impulse tube for splits. Crank seal would do the same but that is in the realms of specialist pressure test.  Did the dealer run your saw at high revs and did it sound as if it was missing then ( 4 stroking). If you can get someone who knows how to tune a saw such as a pro user to listen and give his opinion then that would be very worth while. It might very well be your dealer is right but a second opinion is always comforting.
Regarding fuel, try and use high octane ethanol free. If you only use your saw occasionally use a fuel stabiliser or better still Aspen if available there. Ideally do not use fuel that has been mixed for more than a few weeks.

[John Mc]

Welcome to the forum, Delirium.  I'm just down the road from you in Monkton.

John Mc

[jd2007]

I've got 2 MS250 chainsaws, they're good machines.  I had to replace the piston & clean the cylinder up on one of them as the previous owner trashed it & it's running strong again after a Meteor piston replacement.  I run them with a 16" bar/chain combo.

[CTYank]

No way do you need more than 89 octane (mid grade)- any more is counter-productive.

As has been said, keep the cutters like RAZORS. It is a CHAIN-saw, you know. There's no part-way there. Chain-filing is a most useful skill; grinding is only for rocked chains.