MS 290 muffler mod

[Mad Professor]

My cousins ms 290 muffler needs to be replaced and I might help him out with a muffler mod. I've not worked the 1127 clam shell series.

He is willing to buy a new OEM muffler. If I could locate good used muffler might try using that. Are all 1127 series mufflers, older and newer, about the same concerning flow restrictions, and I assume they all interchange. Is the 039/390 inlet port wider?

Did some searching on muffler mods on these here, most posts are old and missing pictures. If anyone has some pictures they could of post what has worked well that would be great.

So here is some questions:

1) For outlet it seems just open up things under the deflector and retain the screen. How much of that area to remove?

2) Some previous threads the deflector was trimmed/bent for more flow.

3) The baffle inside. Need to remove modify that? If so need to de-crimp the halves to do so? B Snelling mentioned leave it in place.

4) I believe the carb has hi/lo, so just remove limiters and retune.

5) First time seeing the strange screws that hold the muffler on. Comments on these?

Thanks in advance.

 

[dmb2613]

That is an EZ one to do

 

[Mad Professor]

So not much help here ........

What I gather is slot out/connect the existing outlet holes. Leave baffle in place. Open up deflector a bit.

This saw the existing baffle has disintegrated, and parts rattling around inside muffler. Fear is some will come back inside cylinder (not yet) and do damage.

OEM muffer is ~$41, screws ~$2 (X3). Chi-Com knockoffs ~$15-20 with screws.

What is "best" Chi-Com muffler these days?

I guess I'll bleach down the package/muffler, before handling it, because of coronavirus.....