does anyone take there spark screen out of the exhaust? if so why? also i read on here about modifying it somehow to make it run better? faster? any insight would be great got some logs to buck up and was just wondering about my saw and if i can make it perform better without the big price tag of the pro saws. i will get a pro saw one day and keep the 290 for limbing or small wood but right now it works just fine.
ms 290 exhaust
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I modded my muffler on my 290, it did help some. Basically there is a small opening to the muffler, and you make it bigger or add more holes, to allow more air to flow through. It makes it louder/stronger. I left the spark screen in though, I think its technically illegal to have it out in some areas due to forest fires. I think as long as you make sure the spark screen isn't plugged up, its not really harming anything, and probably better to leave that in.
I do recommend the muffler mod though!
I do recommend the muffler mod though!
Before attempting a muffler mod, first get the limiter tabs off the H and L needle of the carb. You will need to richen the mixture beyond what is allowed by the limited tabs after a muffler mod.
When I did an 039 a long time ago, I lined up the tabs and then pulled them out by screwing a drywall screw in to the plastic tab just enough to grab a hold of it. Then trimmed the limiting "ears" off and put the caps back on.
When I did an 039 a long time ago, I lined up the tabs and then pulled them out by screwing a drywall screw in to the plastic tab just enough to grab a hold of it. Then trimmed the limiting "ears" off and put the caps back on.
Thanks Steel, I forgot to mention that part (pretty important too!). It was a royal PITA for me to get one of them off, one went easily, the other just took me forever. I also used a drywall screw, seems like that is about the best method you could use.
Scuttlebutt is, the MS290 responds pretty good to a good muffler mod. Screen is legally required if you cut on public land. You can still modify the muffler but all openings need to be protected by a screen. If you only cut on private property then I didn't see nuttin'. 
A Muf Mod isn't going to turn the MS290 into a pro saw but it sure will help get the best performance from what you have.
When that day comes, I'd sell the 290 as it's way too heavy to be a great limber. They hold resale amazingly well, especially if it says "Farmboss" on the bar. Take the funds and get a 35-40cc saw to scream through the little stuff. 2 new saws is better than one no? 
A Muf Mod isn't going to turn the MS290 into a pro saw but it sure will help get the best performance from what you have.
When that day comes, I'd sell the 290 as it's way too heavy to be a great limber. They hold resale amazingly well, especially if it says "Farmboss" on the bar.
Take the funds and get a 35-40cc saw to scream through the little stuff. 2 new saws is better than one no? 
My Stihl dealer has a rule of un-constipating stuff that comes into his shop if it's out of warrantee. Screen be gone is his best medicine for crummy running saws.
I just did a muffler mod on my 290 and have been pleased with the results. Here are some before and after pics. I left the screen in on mine. I did mod the screen cover a little also. And I used a long drywall screen to get the limiters out of the carb.
Attachments
![[Hearth.com] ms 290 exhaust](/talk/data/attachments/83/83563-7d6fa10de08b0e25c1a773be1eaf3eac.jpg?hash=AbZz0ejMrD)
![[Hearth.com] ms 290 exhaust](/talk/data/attachments/83/83564-40fb97dbc39fdf9640860dd651b5ebb3.jpg?hash=WdpSnVD_xT)
![[Hearth.com] ms 290 exhaust](/talk/data/attachments/83/83565-4616451bb4c9be567a377c3185a21f79.jpg?hash=CBXaSaIVYE)
That would get you a fat fine here, running a saw in fire season w/o a muffler screen out in the woods. Its also not the best solution. Not sure he would be kosher with the EPA for doing that either. As of a few years ago, any saw that comes into a shop that has been modified has to be restored to original EPA specs, by law. Meaning that opened up mufflers have to be replaced with choked up originals, and carb limiters have to be replaced with ones that have tabs on them.
The mod above is in the dimpled area of the muffler. That will certainly work better, but I have found that those tend to run a lot louder than need be. I use the original muffler from the 029 and the European model 290/310/290 saws as a template to mod the 1127 saw mufflers. You can buy these early type mufflers on Ebay for about $20, or drill them out yourself. The original muffler porting on this is designed to give the choked up US models about 10% more power (and restore the original design specs) with the least gain in noise. Note that you must retune the carb richer after any porting (including removing the sparc screen), or you will likely overheat it running it too lean.
Here is the original 1127 saw muffler with porting, with about two times the open area:
![[Hearth.com] ms 290 exhaust](https://www.hearth.com/talk/data/attachments/83/83584-f13fcbfba77ae0e7140c4b61602bbd2c.jpg?hash=ejg9ImJt8u "[Hearth.com] ms 290 exhaust")
The screen cover mod there is exactly what I do. Here is the original screen cover:
![[Hearth.com] ms 290 exhaust](https://www.hearth.com/talk/data/attachments/83/83585-7f352b81fa2843076df810e41fe43aaa.jpg?hash=AFebx95T9M "[Hearth.com] ms 290 exhaust")
Here is my modified screen cover, ground open:
![[Hearth.com] ms 290 exhaust](https://www.hearth.com/talk/data/attachments/83/83586-56da7997e88bd1f3217bbc48802919c3.jpg?hash=wHoj1OfInT "[Hearth.com] ms 290 exhaust")
Here is the original 1127 saw muffler with porting, with about two times the open area:
The screen cover mod there is exactly what I do. Here is the original screen cover:
Here is my modified screen cover, ground open:
mtneer
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(broken link removed to http://www.treeworld.info/f40/ms-390-fine-tuning-questions-12382.html)
I found some great info above. Looks to be Stihlhead's. Only thing is, I have a 311 and I guess the muffler has a shiny crimped casing around the black part you see on the 310. Is this tough to remove to get at the guts?
I'd like to just throw a euro 310 muffler on my saw but that probably wouldn't work.
I found some great info above. Looks to be Stihlhead's. Only thing is, I have a 311 and I guess the muffler has a shiny crimped casing around the black part you see on the 310. Is this tough to remove to get at the guts?
I'd like to just throw a euro 310 muffler on my saw but that probably wouldn't work.
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