Stihl 020AV Muffler Mod

[RES]

I am on a Muffler Mod kick right now. When I took the muffler apart on one of my 020av's, it looked very strange. There are two clamshell halves with a two bolt spacer between. It doesn't seem to have any place for the exhaust to exit. Has anyone modded the muffler on one of these with any success? It seems that you could drill some holes in that spacer.

 

[RES]

I have searched and searched with no success for 020av muffler mods. I don't want to ruin the saw by cutting too much away on that spacer.

 

[Stihl 041S]

Post a couple of pictures, thjat m,ight help folks.

 

[RES]

Here a picture of the 020AV muffler? There are two halves. The spacer is welded to one half. When the two halves are clamped together, there is very little area for the exhaust to exit to the inside of the muffler and then out through the port. My thought would be to drill some holes in the spacer. How many holes and how big is the question that I have? Can anyone offer any help?

 

[Ax-man]

This might help. At least give you an idea anyway.

I am going to say this is a stock modified muffler for an 020. I have run into a few of these mufflers on some 020's. It looks factory made.

This is on my little hot rod 020 that has been changed over to 40 mm, and some porting. It has been a long time since i have done this saw and I honestly can't remember what the muffler looks like on the inside till I take it off and apart. Can't remember if that opening is the same on the inside as it is on the outside.

Larry

 

[RES]

Thanks Ax-man. That muffler looks differant than mine. Mine does not have a screen on the outside. It does not have any screen. See attachment.

 

[nmurph]

mine has a screen in the outlet.
you are right about not much inside. the only improvement that i could see would be to cut some of the outlet away and some of the "box" where the exhaust enters the saw.

 

[Ax-man]

Res, that is the regular plain Jane stock muffler found on most 020's. You won't find a screen in those mufflers. Just the two halves like you described.
Not really much to them.

 

[RES]

Would a reasonable muffler mod be to trim about 1/3 of that spacer or is that too much?

 

[Ax-man]

1/3 might be a tad to much for that muffler. Rule of thumb for modding mufflers is for your outlet to be about 10 to 20 % smaller than the opening of the exhaust port on the cylinder side.

Others may have a different opinion and I do respect that but a muffler needs to have a little back pressure for the scavenging side of the cycle. Too big of an outlet you kind of lose this which affects your tuning.

Personally and this is just me talking. I don't really see the need to mod a simple muffler like that. There is not much to it. Just a simple straight through muffler with that baffle to quiet it down a little. It is not choking the saw.

Just an obsevation from your pic. That saw was running very rich judging by the carbon you were scraping out of it. Clean it up a little more down to the bare metal and see if adjusting the carb makes a difference in how that saw runs.

Larry