025 mods

[Lumberjack]

I have an 250 saw that I use for climbing. I have had it for around 3 months , and I like it. Today it rained so I couldn't work, so I tinkered around, and a friend came over for some firewood. His saw was duller than a butter knife so I used mine to cut the trees up.

Anyway I got to thinkin after he left about openen up the muffler. I wasn't sure if it would make a difference, but when I saw the exhaust port, I knew it would. I opened it up till it was a little smaller than the exhaust port. Man what a difference.

Then I got the 044 out and did the same. The 044's port was the same as the 250 so I opened it up to about the same as its exhaust port, and it seemed to help, but really didn't have anyhting big enough to test it.

Now I will have to wear hearing protection with the 250, but it helped tremendously. What additional mods would yall recomend, and what changes do I need to make to the carb. I re-tunned it the best I could.

Also what additional mods to the 044.


Thanks
Carl

 

[Grateful11]

Hey Lumberjack any chance of some pictures of your mods. I've been wanting to do a few to mine. Great little saw but I wish it would rev up a little faster than it does. Did it help with that?
Grateful

 

[Lumberjack]

Yea I can post some pics tommorrow. They both seemed to rev faster, and I could tell that the 250 cut alot faster, I don't have times, but it was a noticable improvement.

I have had the same saftey chain on the saw for about a month now. One thing I can say about the saftey chain is that the extra bumper links seem to keep the chain sharper longer. I have probably cut around 30 trees on this chain, and havent touched it with a file, and it still pulls nice sized chips at a good rate.

If you have the 025, take the 2 nuts off the end of the can, slide the external deflector to the left (it you are lookin at the saw). remove the can. Get a good sized drill bit and make an aditional hole on each side of the exsisting one. I will do this tommorrow, but I am gonna take a flute cutter on a air grinder and smooth the hole out completely. Then I blew it out with compressed air. Tommorrow I might put a hole in the internal baffle to make it flow even better. The indention where you drill is gonna be my target size for the outlet, with the same shape.

I am gonna look at the external deflector and see if I can't make it flow better while maintaining the stock look.


I was suprised how loud the 044 was without its can on. I was wearing hearing protection, and didn't have have a bar on, turned the exhaust port towards my face, and I could feel the vibration in my sinuses. I gonna smooth out the exhaust hole in the can (I left it on the side) and elong it a little to the back so I can still get the deflector to blow the gasses away from me to some degree.

Soulda done it when I got it.

Carl

 

[sonny]

just remember there 2 strokes. when the piston does suck . when the muffler is modified. it sucks in dirt & dust.make sure the screen is on.

 

[rahtreelimbs]

Originally posted by Grateful11
Hey Lumberjack any chance of some pictures of your mods. I've been wanting to do a few to mine. Great little saw but I wish it would rev up a little faster than it does. Did it help with that?
Grateful

Here are some muffler mod pics that I posted about 2 months ago, hope this helps!


http://www.arboristsite.com/showthread.php?s=&threadid=11333&highlight=muffler+mod+photos

 

[rahtreelimbs]

At the suggestion of Ken Dunn I always put screens on any muffler mods that I do.

 

[IOU1]

sonny

I find your sucking piston theory very interesting. I am not suggesting that you are incorrect about it but could you please explain it for us.
I was considering trying to do a Walkerized style muffler on my 359 Husky. If it will suck dirt back via the exhaust pipes, I will look for another alternative. Do the Walkerized saws have a problem with dirt being sucked in?

 

[Lumberjack]

I too am curious. My understanding is that the piston travels up(compression), detonates the mix which sends the piston down (power), then the exhaust port is exposed slightly before the intake to maximize the scavenging effect (intake and exhaust). During use there is a constant (albet pulsating or surging) positive pressure for a duration of the cycle. When is there a negative pressure in the exhaust? Also wouldn't the spent charge comming from the port keep all the dust ect from reentering the cylinder? I don't understand your theory, would you elaborate?


Thanks
Carl

 

[rahtreelimbs]

I'm not sure exactly how the negative pressure of the exhaust happens. I had a phone conversation with Ken Dunn ( one of our resident modified saw builders ) last year. He told me to install a screen over any modifications that I did. Some don't believe in this theory. I figure why chance it. There are some sawyers that use screens just to keep mud wasps and the like from building nests in the mufflers too!

 

[glens]

Carl, I don't think there's ever any meaningful (if measurable) reverse flow pulses through the muffler during normal running mode.  There might could be some abnormal situations though where it might exist, such as very early in the start-up mode or something (before any heat is produced above the piston).  Mud daubers &c. are the major reason I like screens.

Glen

 

[Tony Snyder]

Sonny,

There is no such thing as suck, "Fluid Dynamics", chapter one. Back me up, Babcock or any of you techs.

Just a little technical point Sonny, don't intend to insult you.

 

[WRW]

Tony,
I'm not a tech, but " to draw something in by or as if by a vacuum" seems general enough that it shouldn't exclude "Fluid Dynamics". Doesn't a lower pressure area have to be created before a higher pressure can push toward it?
I love hearing about how sailboats are pulled, not pushed.

 

[DirtTroll]

I would hate to see another urban saw legend get started so:

There will be a suction between when the piston travels from opening the exhaust and opening the intake port. As the piston continues to travel down volume is increasing. You can see this using a simplified Bennoullis equation assuming no outside factors: P1/V1 = P2/V2

Therefore there will be suction.

How much suction will there be from the muffler? NONE. There will be enough positive pressure still in the muffler to not allow flow back into the muffler. The muffler will not have dissipated the presure wave quickly enough during the suction portion of the stroke as long as the muffler hole does not exceed the exhaust port.

So, the only reason for the screen is for spark arresting and possible mud bee exclusion. No dirt will be sucked back in.

 

[Lumberjack]

Here is a pic of what I did. I probably will take a flute cutter and smooth is out though.

To see it better (It looks dark otherwise, but exposure is good) adjust contrast if needed to see in the muffler.

Carl

 

[tony marks]

my concern here,, would be the increased rpm. i have opened several ..
the last an 026 yesterday. dont u need to adjust the wot rpm to saw specs after
u do this.. or does that just defeat what u trying to do...if u do adjust to specs,, have u just made u saw louder,, or is it stronger in cut.i accidentally ran the saw with front of muffler off yesterday,,and she went over 15400.
now iis that alrite ... it got me to thinking ,,which is a dangerouse thing..
when i got a saw in my hand.