MS 241 compression only 120 PSI

[Fairways_and_Greens]

I let my buddy borrow my MS241. The compression is only 120 PSI... With the same tester my 044 is 155. I just checked the 241 squish and it's at .31...

I think he might have ran regular gas through it? I checked the exhaust port and saw no scoring. I'll pull the big off tomorrow. But for reference decompression should a stock 241 have?

 

[Wonkydonkey]

It’s on the low end of compression, but that’s Depending on age and usage, it maybe a bit scoring that you can’t see.
I will be waiting to see what you find. Pic’s .....of p&c...
In the meantime I’d be planning this

 

[Fairways_and_Greens]

Thanks. Do you know what a stock number is?

 

[Dub11]

140-150 psi I'd imagine. My 290 blows a little over 150 psi.

 

[Michael Rupley]

Don't loan out your saws! (and don't give him any of your ling cod)
Would be nice to know a little more history. If the 044 is almost new and the 241 has a hundred cords on it or what? What mix do you use? Does the saw still run now with 120#? What are you trying to find out? Yea I know you want someone on here to pipe in and say well it should have 155# but then what? Mike

 

[Fairways_and_Greens]

Good point Mike. Next step is to pop the jug regardless.

Saw still runs. It's been ran a lot. It gets the most use around my place. It fits in nicely on back of my baby tractor.

I'm trying to figure out how to setup my timing wheel from @Mastermind 's post (http://opeforum.com/threads/part-one-the-exhaust-port.7279/)

I'd like to take a shot of cleaning the ports up since I'll have it apart.

 

[Al Smith]

.

I think he might have ran regular gas through it? ?

Regular gas meaning not high test or meaning no oil ?

 

[Fairways_and_Greens]

Regular gas meaning not high test or meaning no oil ?

si on the oil

 

[Fairways_and_Greens]

Here are the pictures of the piston and cylinder. I’ve been using Honda HP2 mixed with ethanol free premium at a ratio of 36:1.

 

[Al Smith]

It doesn't look bad . Stihl had some problem with leakage around the plug ,don't know if that could be .Decomp maybe assuming it has one .Soap suds around either should show a leak if there is one

 

[porsche965]

The only way I loan out a chainsaw is if I go with it.

 

[Michael Rupley]

Looks pretty good for high mileage. Mike 36:1

 

[Wonkydonkey]

May be worth seeing what the ring end gap is, it’s just a thought You could be losing some psi there,

 

[Al Smith]

A question because I don't know .Could it be such a thing because this is a version of whatever they call that fresh air blow down design that the compression reading would be lower at cranking speeds ?I've never worked on this design so I'm basically dumb as a rock of what to expect .

 

[Funky sawman]

Put your old rings in the bore and square them up, then check your end gap. Also check spring tension, this is hard to do by feel if you dont have new rings to compair to

 

[Funky sawman]

A good way to cook rings (take the tension out) is to run the saw long and hard then shut the saws off without cooldown idle.....and if the piston stops at tdc were cool air cannot remove heat from the rings via the ports during heat soak. When i shut down a saw after a long cut, i pull it over to make sure the exhaust port is open to cool inside of piston and cylinder.

 

[Fairways_and_Greens]

A good way to cook rings (take the tension out) is to run the saw long and hard then shut the saws off without cooldown idle.....and if the piston stops at tdc were cool air cannot remove heat from the rings via the ports during heat soak. When i shut down a saw after a long cut, i pull it over to make sure the exhaust port is open to cool inside of piston and cylinder.

I'm not sure that follows the laws of thermodynamics?

 

[Funky sawman]

Well i have to make up my own laws around here, cause crap is always way more complicated than it needs to be