# MS290 muffler mod



## ikessky (Jan 18, 2010)

Well, after a having the saw for close to a year and doing a bunch of reading on muffler modding, I finally decided to go a head and do it.  I should have taken some pictures, but didn't really have the time since the littlest one was chasing the dog around the garage while I was trying to work!  Basically, I combined the two existing slots into one large opening.  It's not straight piped like a lot of the ones you see, but I may take it apart again and add one or two small holes in that area.  I sliced the tabs off the red limiter caps and the reinstalled them, set the L screw to about 1 turn out and the H to 1.5 and tuned from there.  It's probably still a little on the rich side, but I didn't want to over do it since I didn't have a tach to use.

All in all, it wasn't a hard job and I might have picked up a little power from it.  Hard to tell since I didn't really have any wood laying down to really try it out and I didn't want to go out felling trees with a 1-year-old tagging along!


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## HittinSteel (Jan 19, 2010)

Post up some pics when you get a chance....... there still may be a lot of gains left in the saw depending on the size of the opening


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## smokinj (Jan 20, 2010)

HittinSteel said:
			
		

> Post up some pics when you get a chance....... there still may be a lot of gains left in the saw depending on the size of the opening



+1


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## ikessky (Jan 20, 2010)

So I should probably just add a few holes into the depression and tune it again?  The mod I did still puts the exhaust through the baffles.


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## HittinSteel (Jan 20, 2010)

Here's how I did mine (and several others). I put the screen back in after the picture.


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## smokinj (Jan 20, 2010)

ikessky said:
			
		

> So I should probably just add a few holes into the depression and tune it again?  The mod I did still puts the exhaust through the baffles.



post a few pic's it will really help


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## Highbeam (Jan 20, 2010)

I was running my saw, the 290, two days ago felling some junk trees. When shortening the stumps I noticed that the mufflers on these saws are very quiet. The intake suck sound is very loud. I expect that you could open up that OEM muffler quite a bit before even being able to hear it over the intake.


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## smokinj (Jan 20, 2010)

HittinSteel said:
			
		

> Here's how I did mine (and several others). I put the screen back in after the picture.



that looks good


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## smokinj (Jan 20, 2010)

heres mine


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## ikessky (Jan 21, 2010)

The exhaust is taking the path of least resistance right?  So, I should be able to add a couple smaller holes in the depressed area above the baffle and not hurt anything right?  If these holes cannot flow all the gasses, it will then take the path through the baffle.  Is my thinking correct here?


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## smokinj (Jan 21, 2010)

ikessky said:
			
		

> The exhaust is taking the path of least resistance right?  So, I should be able to add a couple smaller holes in the depressed area above the baffle and not hurt anything right?  If these holes cannot flow all the gasses, it will then take the path through the baffle.  Is my thinking correct here?



hittensteel has it perfect I Would rather have one opening.


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## southbound (Jan 21, 2010)

Did you open up the cover any???

I drilled into the depressed area and opened up the out on the front cover as well....


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## ikessky (Jan 21, 2010)

Not my picture, but this is basically what I did.  My opening is straight across though.  I didn't make the small vertical leg like this guy did.


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## southbound (Jan 21, 2010)

That seems to be a popular way of doing it....Should work fine....

I got a 064 muffler that needs a pipe welded on the side....Gonna have to pay someone for that tho....


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## smokinj (Jan 21, 2010)

ikessky said:
			
		

> Not my picture, but this is basically what I did.  My opening is straight across though.  I didn't make the small vertical leg like this guy did.



Now do you know how to tune it you opening should be enough?


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## ikessky (Jan 21, 2010)

I took my tuning process from the Madsen's site.  Tuned the L screw to a point halfway between where it starves for fuel and where it loads up and runs the chain.  Tuned the H screw to a point where it is 4-stroking at WOT no-load.  Like I said before, I'm not sure but I might have it a little richer than it needs to be as I didn't think that the 4-stroking went away when I put it into wood.  Then again, I tried it on a half rotted piece and a few pieces of 2x12 lumber.


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## smokinj (Jan 21, 2010)

ikessky said:
			
		

> I took my tuning process from the Madsen's site.  Tuned the L screw to a point halfway between where it starves for fuel and where it loads up and runs the chain.  Tuned the H screw to a point where it is 4-stroking at WOT no-load.  Like I said before, I'm not sure but I might have it a little richer than it needs to be as I didn't think that the 4-stroking went away when I put it into wood.  Then again, I tried it on a half rotted piece and a few pieces of 2x12 lumber.



your dead on track better to be on the rich side. Best to listen to it in the cut and make adjustment from ther if need be.
You should be able to notice a diffrence in the larger wood when the bar is baried


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## ikessky (Jan 21, 2010)

I'm going to open the slot up a little more and then do some more tuning when I can get into some actual larger hardwood.  I think my FIL has some sitting by his OWB that he wouldn't mind me cutting, so that should help me out as I'm not going to be trudging through the woods in the snow right now.


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## smokinj (Jan 21, 2010)

ikessky said:
			
		

> I'm going to open the slot up a little more and then do some more tuning when I can get into some actual larger hardwood.  I think my FIL has some sitting by his OWB that he wouldn't mind me cutting, so that should help me out as I'm not going to be trudging through the woods in the snow right now.



A total of 1/2-9/16 opening is the sweet spot for a 55cc saw. my 460 is at 3/4 opening its 77cc


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## ikessky (Jan 21, 2010)

I assume you are talking square inch opening?  Removing and reworking the muffler is pretty easy, so maybe I'll take it back off and do some measuring.


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## smokinj (Jan 21, 2010)

ikessky said:
			
		

> I assume you are talking square inch opening?  Removing and reworking the muffler is pretty easy, so maybe I'll take it back off and do some measuring.



I am talking about the opening in the cover only


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## ikessky (Jan 21, 2010)

The deflector?  Yeah, I didn't open that up a lot.  I still could take some off of it to.


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## smokinj (Jan 21, 2010)

ikessky said:
			
		

> The deflector?  Yeah, I didn't open that up a lot.  I still could take some off of it to.



if your opening is line up with the deflector it should be as good as it gets


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## ikessky (Jan 22, 2010)

So do you think that drilling a hole in the depression would hurt now that I've opened the slots up?  Would I have too large of an opening at that point?


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## smokinj (Jan 22, 2010)

ikessky said:
			
		

> So do you think that drilling a hole in the depression would hurt now that I've opened the slots up? Would I have too large of an opening at that point?



get a measurement and see where your at.....?


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## ikessky (Jan 25, 2010)

I think I'll fine tune it and call it good with what I've already done.  It is an improvement over stock and that's good enough for me.  Heck, just having the limiter tabs gone and being able to fully tune it is an improvement over stock!


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## ikessky (Feb 6, 2010)

Just an update.  Took the saw out this AM and tested it and tuned it some more on some decent hardwood that my FIL had sitting in his pile.  Once the saw started, I let it idle for a few minutes and then reved it a little so that I would be working with a warm engine and could get a good tune.  Next I made some light cuts and then let it idle a little more.  Finally, I cracked it wide open and got a nice little four stroking sound.  I leaned it out, the richened it up until I was back to the four stroking/rough sound.  Then, I went at some pieces of wood.  Right now, when I got WOT, the saw four strokes.  As soon as you get it into the wood, it smooths out until you pull out of the cut.  So, from everything I can find, I should be tuned perfectly now.


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## smokinj (Feb 6, 2010)

ikessky said:
			
		

> Just an update.  Took the saw out this AM and tested it and tuned it some more on some decent hardwood that my FIL had sitting in his pile.  Once the saw started, I let it idle for a few minutes and then reved it a little so that I would be working with a warm engine and could get a good tune.  Next I made some light cuts and then let it idle a little more.  Finally, I cracked it wide open and got a nice little four stroking sound.  I leaned it out, the richened it up until I was back to the four stroking/rough sound.  Then, I went at some pieces of wood.  Right now, when I got WOT, the saw four strokes.  As soon as you get it into the wood, it smooths out until you pull out of the cut.  So, from everything I can find, I should be tuned perfectly now.



yes sir perfect as it gets


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## ikessky (Feb 6, 2010)

Probably would have been an even more noticeable change had I sharpened the chain before hand!  Can't wait to try a full chisel once I start cutting in a month or so.


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## smokinj (Feb 6, 2010)

ikessky said:
			
		

> Probably would have been an even more noticeable change had I sharpened the chain before hand! Can't wait to try a full chisel once I start cutting in a month or so.



full chisel will make a big difference as well, should be a nice set up.


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## ikessky (Feb 6, 2010)

A buddy from work was going to look at the 290's this weekend.  Hopefully he picks one up so I can see how mine runs vs his.


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## Highbeam (Feb 6, 2010)

I own and have been arond lots of 4stroke bikes. Is this term "four stroking" the sound of a 4stroke bounding off the rev limiter? Kinda of a bouncy na-na-na-na sound? Ther term four stroking isn't very descriptive.


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## ikessky (Feb 6, 2010)

Kind of, I guess.  Fiddle around with your H screw while the saw is at WOT once.  When it's lean, it will sound very smooth.  If you richen it up so that starts to sound "rough", that will be when it's four stroking.  I guess Google it and see what you come up with.  If you look at Madsen's page, they have some sound files that are very good.


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## Jamess67 (Feb 7, 2010)

doesnt all this make the saw ALOT louder???


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## ikessky (Feb 7, 2010)

Depends on how you do the muffler mod.  On mine, the gases are still going through the baffle.  It's a touch louder, but not very much.  If you drill above the baffle and straight pipe it, then it will be quite a bit louder.  In reality though, we should all be wearing hearing protection when running the saws.


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## Jamess67 (Feb 10, 2010)

ikessky said:
			
		

> Depends on how you do the muffler mod.  On mine, the gases are still going through the baffle.  It's a touch louder, but not very much.  If you drill above the baffle and straight pipe it, then it will be quite a bit louder.  In reality though, we should all be wearing hearing protection when running the saws.



I do wear full protective gear. I just dont want  the neighbors complaining.


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## ikessky (Feb 10, 2010)

Mine is a little louder, but not overly obnoxious.  I turned the two existing slots into one larger slot and then opened up the deflector a little.  The exhaust still goes through the baffle, which is really what kills the sound.


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## southbound (Feb 10, 2010)

My MS 290 did get a little louder but it is not bad at all.. Now the muffler I just had modded for my 064 is going to be a screamer.....












The second port...


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## smokinj (Feb 10, 2010)

nice job southbound


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## southbound (Feb 10, 2010)

Thanks but I did not do it I had a member from another forum do it up for me...


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## smokinj (Feb 10, 2010)

southbound said:
			
		

> Thanks but I did not do it I had a member from another forum do it up for me...



who was it brad?


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## southbound (Feb 10, 2010)

Nope Evan.....


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## smokinj (Feb 10, 2010)

southbound said:
			
		

> Nope Evan.....



I know of him and thats some nice work.


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## ikessky (Feb 10, 2010)

Nice!  I'm thinking about starting to look for a 440 that needs a rebuild.  I think a dual port muffler will be in order for that one.


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## southbound (Feb 10, 2010)

I'm happy with it...


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## smokinj (Feb 10, 2010)

Ok who put them big dawgs on there?


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## southbound (Feb 10, 2010)

They came with the saw...


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## smokinj (Feb 10, 2010)

southbound said:
			
		

> They came with the saw...



The way I cut its much quicker with the bump strips and you get more out of your bar, Unless your just felling most of the time.


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## southbound (Feb 10, 2010)

I have no need for this 064 I traded a 031 rear handle for what was supposed to be a running 066..It turned out to be a 064 with a bad P&C...
So this saw will be my felling saw for the big stuff the 038 wont like...


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## ikessky (Feb 10, 2010)

I have no need for a 440 either.   But why not?  I won't get serious about a different saw until the kids can start cutting with me.


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