MS 290 Muffler -Mod: Longevity?

[CountryRhodes]

Hello, I am new to AS. I have a Stihl MS 290 that is completely stock. I take care of it, and I don't really want or need a bigger or more powerful saw, but I am considering doing the muffler mod that is spoken of so often on this site. Again, it's not that I need the extra power, I just enjoy tinkering with things. I understand having to re-tune the carb after opening the muffler, so my only question would be this:

Does anyone know for sure, from experience, if doing a muffler mod and carb re-tune will affect the life span of the engine?

Thanks in advance for any answers, and you guys have an awesome site here.

 

[struggle]

If properly tuned it will have no effect on life of the saw.

If anything it will hold out longer as it will be able to operate slightly cooler due to the reduce exhaust temp in my mind since it is so heavily restricted

 

[old-cat]

The old STIHL saws had open mufflers and larger outlets than these newer saws. All you need to do is copy the old saws, take all the baffle crap out and make a larger outlet. If that reduces life, I think STIHL would have never done it before.

Actually the new fangled closed mufflers reduce the life of the saw because they run hotter.

 

[Stihlofadeal64]

You should be fine over the long haul. Just maintain your air filter and make sure that you have your carb tuned properly on the high side. The mod should give you more grunt in the cut. You should be happy with it (not to mention the real cool sound.).

 

[Zombiechopper]

modding mufflers on modern saws increases longevity by decreasing operating temperatures. Chainsaws made before epa requirements were never as restricted as today's saws and they had superb durability. Just in the production lifespan of the 029/290 alone the outlet sizes have decreased. Same with 046/460 muffler outlets. Stihl has made the openings smaller over time to reduce emissions.

 

[Dan_IN_MN]

Welcome to AS!

I'm a little surprised by all of the answers that all just about repeat each other. :msp_scared:

All good advice given! I'd just like to add to keep your chain sharp. A dull chain can cause the operator to push harder on the saw, causing the saw to run hotter. Also, a dull chain creates dust that plugs an air filter quicker. Besides, a sharp chain is more fun as the saw drops through the cut! :msp_wink:

 

[nstueve]

if you want proof in the pudding... I have rebuild 5-8 ms290/390's for a tree company that uses them every day for work and has been thrashing my rebuilt saws for the last 3 years with no problems. If anything the muffler mod and carb tune improves longevity b/c the saw runs with more oil/gas to lube and cool, and the muffler is allowed to "exhale" the heat that would otherwise be trapped in the muffler right next to the exhaust side of the piston. Also 3 years of heavy duty tree service use equals 10+ years on a 2-4cord a year home owner saw.

Biggest thing that will help prolong your saws life is a good synthetic two cycle oil mix with fuel stabilizers. If you have conventional now... THROW IT OUT! I use Woodland Pro synthetic 2cycle. $11 for 6pack of 2.5gallon mix bottles!

 

[roostersgt]

if you want proof in the pudding... I have rebuild 5-8 ms290/390's for a tree company that uses them every day for work and has been thrashing my rebuilt saws for the last 3 years with no problems. If anything the muffler mod and carb tune improves longevity b/c the saw runs with more oil/gas to lube and cool, and the muffler is allowed to "exhale" the heat that would otherwise be trapped in the muffler right next to the exhaust side of the piston. Also 3 years of heavy duty tree service use equals 10+ years on a 2-4cord a year home owner saw.

Biggest thing that will help prolong your saws life is a good synthetic two cycle oil mix with fuel stabilizers. If you have conventional now... THROW IT OUT! I use Woodland Pro synthetic 2cycle. $11 for 6pack of 2.5gallon mix bottles!

What he said! I have a friend who uses 290's exclusively in his firewood business and he has modded all of his saws. The muffler mod will do all that has been described, plus it will give the saw much faster throttle response. Much faster, plus more grunt in the cut. It'll surely surprise you if you're only used to the stock version. I sure was.

 

[CountryRhodes]

Will I also need to remove the limiter caps from my carb in order to get it rich enough for the open muffler? If so, anybody know the best way to do that without screwing anything up?

 

[Scooterbum]

Doesn't need or want more power??????????

I think we need a man-card check here..........

 

[CountryRhodes]

Doesn't need or want more power??????????

I think we need a man-card check here..........

I guess "don't need, but do want" is more like it.

 

[Moparmyway]

In addition to what others have said, while in the cut - you will be at higher rpm, allowing more cooling air across the fins, more cooling fuel/air charge to the case, and less time in the cut since it will cut faster ..............

On the down side, you will definately need earplugs after the mod ....... but earplugs are cheap !!

MM and re-tunre it now !!

 

[nstueve]

In addition to what others have said, while in the cut - you will be at higher rpm, allowing more cooling air across the fins, more cooling fuel/air charge to the case, and less time in the cut since it will cut faster ..............
On the down side, you will definately need earplugs after the mod ....... but earplugs are cheap !!
MM and re-tunre it now !!

I think most guys need one of these anyhow...
View attachment 278822

Will I also need to remove the limiter caps from my carb in order to get it rich enough for the open muffler? If so, anybody know the best way to do that without screwing anything up?

Yes you'll need to turn both H&L needles clockwise until lightly seated. Then counter-clockwise to open them 360 degrees or 1 full turn. This should set a good base timing to work from.

As far as removing the limiter caps...
1.) Find drywall or deck screw.
2.) Screw into limiter caps
3.) Pull out
4.) Throw limiter caps away.
5.) Tune carb
6.) Go test cut a few cookies
7.) Go drink a beer!

 

[BigMoneyGrip]

If anything the muffler mod and carb tune improves longevity b/c the saw runs with more oil/gas to lube and cool, and the muffler is allowed to "exhale" the heat that would otherwise be trapped in the muffler right next to the exhaust side of the piston.

Also know that the engine is burning this extra fuel and oil, which creates even more BTU's.

I think the main thing that helps, is being able to get a more ideal air/fuel ratio by pulling the limiters and adjusting the carb. This alone will lower the running temps.

 

[CountryRhodes]

Yes you'll need to turn both H&L needles clockwise until lightly seated. Then counter-clockwise to open them 360 degrees or 1 full turn. This should set a good base timing to work from.

I did the muffler, pulled the limiters and set the needles to 1 turn each. I went to tune it (first time tuning a carb) got the idle set, did the L screw with no problem, and when it came to the H screw wasn't exactly sure where I ended up, other than I know I'm 1 & 1/4 turns out from closed. I know it's not too lean, and I know I'd rather be too rich than too lean, but I'm having trouble finding "the edge of the 4 stroking".

Should it be ok where it is, or anyone have any advice? Thanks a bunch for all the help y'all have already given.

 

[moody]

Turn your fine idle out a 1/4 turn rev it let it idle then rev it. Should probably be close.

 

[H 2 H]

I did the muffler, pulled the limiters and set the needles to 1 turn each. I went to tune it (first time tuning a carb) got the idle set, did the L screw with no problem, and when it came to the H screw wasn't exactly sure where I ended up, other than I know I'm 1 & 1/4 turns out from closed. I know it's not too lean, and I know I'd rather be too rich than too lean, but I'm having trouble finding "the edge of the 4 stroking".

Should it be ok where it is, or anyone have any advice? Thanks a bunch for all the help y'all have already given.

All saws will be different on the screw settings it depends on how much you open the MM (mufflers opening)

This one with theses open is about 2 1/8 turns on the "H" screw (this is on a 390)

It is also cleaned out inside the muffle (no baffle)

Don't forget to open up the cover on the muffler; if you don't your really not doing a MM

 

[mtfallsmikey]

Modded my muff 3 yrs. ago, retuned, never looked back, still goin' strong, use HP Ultra/good non-ethanol gas, good to go....

(Sounds like something I did at the junior prom, doesn't it?)