Opinion on MS440 piston

[MontanaTed]

I need an opinion on a piston. To me it looks like it is scratched/scored (maybe one in the same).

Left side small straight scratch.

What do you guys think? Harmful to run? Pulling 145 psi on my Guage (with out proper fitting) @ about 3300 FASL.

 

[Chris_In_VT]

If it were mine, I'd run it and keep an eye on it.


Then again, I've heard Stihl OEM pistons are dirt cheap now. Replace and have a serviceable emergency backup?

 

[blsnelling]

That piston is entirely fine. It doesn't even show much wear. No way does it need replaced. I would recommend that you pull the cylinder and decarbon the exhaust port. Might as well clean up the piston crown and combustion chamber while you're at it.

 

[MontanaTed]

That piston is entirely fine. It doesn't even show much wear. No way does it need replaced. I would recommend that you pull the cylinder and decarbon the exhaust port. Might as well clean up the piston crown and combustion chamber while you're at it.

Thanks Brad, that's what I was thinking on the piston but I tend to lean on the psrinoid side.

Now if I can build the confidence to do the decarbon work. I haven't done much work to small engines, mostly cars...

 

[MontanaTed]

Here's the whole saw, it's new to me used.

 

[blsnelling]

That's a very nice saw. Congrats. No fear in pulling the topend. They're very easy to work on.

 

[treesmith]

A dual port muffler and a retune would make it run better too

Square chain though is optional

 

[MontanaTed]

That's in the plans, I was thinking of a HD2 filter also.

I guess I've never seen the inside of a 440 muffler, but thus one is empty, nothing in it but a screen covering the exhaust opening.

 

[blsnelling]

Start with opening up the muffler exit as large as what the deflector covers.

 

[MontanaTed]

Will do, it's hard not to tinker right now, but I'm thinking the neighbors may not appreciate the noise at 9:30.....draw backs of living in the neighborhood

 

[cgraham1]

Might as well install some new piston rings while you have the top end off. That should bring your compression up to where it should be.

 

[drf255]

Might as well install some new piston rings while you have the top end off. That should bring your compression up to where it should be.

+1

And check squish before its apart. Tighten it up to .020ish, or whatever the pro's here say.

Will feel like a different saw.

 

[MontanaTed]

^Clint that Dolmar is just plain jazzy...... Awesome looking saw

 

[cgraham1]

Thanks! It runs damn good, too.

 

[MontanaTed]

I'll bet, I had my eye on one, but the 440 will do nicely for now.

What bars does everyone like? I'm thinking a 28" lite weight, not sure on brand. I have large cotton woods I cut off and on. I will most likely run my 25" ES on it for most of my cutting. Been thinking of a Sugi or Tsumura in 28" opinions? Or are Stihl the way to go.

 

[MustangMike]

In 20 & 24", that is the way to go, but in 28" the Stihl ES Light bar is lighter.

Find the chart that Redbull660 posted, he has wts for all of them.

 

[MontanaTed]

I was looking at that chart Redbull posted.. had to take some serious time! Well for me it would I'm terrible at excell.....

Wish I didn't like shiny objects so much....

 

[cgraham1]

I'll bet, I had my eye on one, but the 440 will do nicely for now.

What bars does everyone like? I'm thinking a 28" lite weight, not sure on brand. I have large cotton woods I cut off and on. I will most likely run my 25" ES on it for most of my cutting. Been thinking of a Sugi or Tsumura in 28" opinions? Or are Stihl the way to go.

Nothing wrong with a 440... I just got this one yesterday! I like the 24/25" bar on mine, but I am going to stick with a 20" because I have other saws with 24, 28, and 32" bars already.

 

[MustangMike]

Nice looking saw, you going to send it on vac to TN?

 

[MontanaTed]

That's aperti saw Clint, good find! I'm leaning more towards just sticking with the 24/25.....