First Muffler Mod -- MS 250 -- w/ Pics

The weather has finally made it comfortable enough to get out to my unheated garage and start prepping my saws for some spring cutting. I have been re-reading various threads of muffler mods and decided to give it a try.

I used a step down drill and elongated the OEM 3/8" diameter hole to be a 1" by 3/8" oval on the front plate, took the same drill to interior baffles and used a large screwdriver to open the exterior baffles. I did leave the spark arrestor screen as I cut on other's property and prefer to be invited back.

I turned up the carburetor setting to the max setting -- given the limiter, as I did not have enough time yesterday before I shut it down for the night. I did get a chance to make a couple test cuts and does seem to be more throaty than previously, but will really need to wait until I get to do some real cutting to know for certain.

All in all it took about 30 mins to remove, drill, clean out debris and re-assemble. Thank you to AS members for the inspiration and know how. Maybe I will work my way through the rest of my arsenal.

Step drill used to elongate holes:
<a href="http://s678.photobucket.com/albums/vv142/GM_DaddyMac/?action=view&amp;current=MS250_Muff_Mod007-1.jpg" target="_blank"><img src="http://i678.photobucket.com/albums/vv142/GM_DaddyMac/MS250_Muff_Mod007-1.jpg" border="0" alt="Photobucket"></a>

<a href="http://s678.photobucket.com/albums/vv142/GM_DaddyMac/?action=view&amp;current=MS250_Muff_Mod003-1.jpg" target="_blank"><img src="http://i678.photobucket.com/albums/vv142/GM_DaddyMac/MS250_Muff_Mod003-1.jpg" border="0" alt="Photobucket"></a>

Used same step drill to open the holes in the inner baffles -- you can see (hopefully) the larger and original small holes.


Finished product w/ the pried wider outer baffles
<a href="http://s678.photobucket.com/albums/vv142/GM_DaddyMac/?action=view&amp;current=MS250_Muff_Mod001-1-1.jpg" target="_blank"><img src="http://i678.photobucket.com/albums/vv142/GM_DaddyMac/MS250_Muff_Mod001-1-1.jpg" border="0" alt="Photobucket"></a>

That will make it run better. Good job.

looks good!

sbhooper said:

That will make it run better. Good job.

Click to expand...

Thanks. I am eager to try it in something more than a big chunk -- but at the moment that is all I have at hand.

Tonight I will work on getting the limit cap off and see if I can dial it in a bit better.

BTW -- how aggressive was my approach compared to others that have MM'd an MS250 -- less, more, same?

GM_DaddyMac said:

Thanks. I am eager to try it in something more than a big chunk -- but at the moment that is all I have at hand.

Tonight I will work on getting the limit cap off and see if I can dial it in a bit better.

BTW -- how aggressive was my approach compared to others that have MM'd an MS250 -- less, more, same?

Click to expand...

It's a tad more aggro than mine. However, I did remove the center louver on the outer plate. I have the carb adj against the stops right now and it works fine. It has an amazing amount of torque for a little ms250. And now it has plenty of top end.

I removed the baffle on mine and opened the stock hole as far as I could. Before I did this I had 3 holes drilled in the bottom of the muffler but had to plug them cause it was to much. Saw runs amazing now though and is night and day. Install the wt-215 fully adjustable carb and your good to go.

Thats almost exactly how I did my pop's. I did leave the screen out, thoug. As for the carb, I just removed the roll pin so the screw could open more.

Thanks to all for the feedback. I will provide an update after I give it a good work out.

Good job,mine is almost identical to yours ,youll hafta get the limiter tab off carb then tune.you will be suprised what a MM can do to this little saw!

Glad to see you made it through the winter. It's nice to work in the unheated garage on days like today. High 60's low 70's is perfect. I just picked up a 250 that needs a new piston. Maybe I might try a muffler mod on it to see how it runs.

Looks good to me, you'll be glad you did it. The 250 becomes a happy little brute with a muff mod.

GM_DaddyMac said:

Thanks to all for the feedback. I will provide an update after I give it a good work out.

Click to expand...

any update on how it turned out? i just did the same muff mod to my ms250 and am wondering if im gonna need to adjust the carb beyond the 3/4 turn its allowing me right now. im assuming i only need to adjust the H carb setting with this?

In case you missed it, here's my MS250 at about 2:35 with it's MM:

<iframe title="YouTube video player" width="480" height="390" src="http://www.youtube.com/embed/r1VRHEn-r68" frameborder="0" allowfullscreen></iframe>

wyk said:

In case you missed it, here's my MS250 at about 2:35 with it's MM:

<iframe title="YouTube video player" width="480" height="390" src="http://www.youtube.com/embed/r1VRHEn-r68" frameborder="0" allowfullscreen></iframe>

Click to expand...

that thing pulls pretty good! did you modify the carb so you could adjust it further?

timmmberrr said:

any update on how it turned out? i just did the same muff mod to my ms250 and am wondering if im gonna need to adjust the carb beyond the 3/4 turn its allowing me right now. im assuming i only need to adjust the H carb setting with this?

Click to expand...

Thanks for the inquiry. I did adjust the H about an 1/8 turn richer, as I was concerned it was a bit close to max RPM. I do not have a tach, so thought I would be safe than sorry.

I had it out this weekend cutting up some blow downs and given the tight quarters and smaller wood size it was a perfect fit. I can definitely see and feel a performance difference. I will try to capture some video this coming weekend.