MS290 Muffler Mod...Dead Horse Gets Beat Again

[Johnnybar]

Guys, I've searched and found so many different versions of modding MS290 mufflers that I gave up on trying to figure out who was right. Some have opened up every restriction so much that there could not possibly be any back pressure and some haven't while all report "runs better than ever" which I'm sure is true. I am going to give some numbers for my muffler in mm's and would like input from those that really know what they are talking about when it comes to getting the sweet spot out of these little homeowner saws. I would like to get the best power improvement with this mod that is possible on the first try. Thanks for you help.

Muffler Intake from the cylinder, 28X18 with rounded corners = ~500 mm2
Internal Baffle tube 22ea 5mm holes = 432 mm2
Muffler exhaust outlets, 2ea 5X10, 2ea 4X7 = ~150 mm2
Cap to be modified as required (easy access).

 

[1Alpha1]

Many are under the impression that anything louder is always better.

I AM NOT AN EXPERT on muffler modding. Having said that...........just start drilling holes and tearing out baffles (if there are any) until you get to the highest decibel level that you can stand.

 

[Mac&Homelite]

Many are under the impression that anything louder is always better.

I AM NOT AN EXPERT on muffler modding. Having said that...........just start drilling holes and tearing out baffles (if there are any) until you get to the highest decibel level that you can stand.

That being said, wouldn't it just be easiest to remove the muffler completely? Actually did try that once, and that will be the last time! lol

 

[1Alpha1]

That being said, wouldn't it just be easiest to remove the muffler completely? Actually did try that once, and that will be the last time! lol

When I was a kid, I had a mini-bike, as well did some of my friends.

They swore that removing the muffler from their engines and then screwing in a straight piece of pipe, improved power. Funny thing! They still couldn't beat me in a drag race.

And, it pissed off the neighbors and made it all that much easier for the cops to find us.

 

[s sidewall]

A two stroke muffler has to have some back pressure to get the best performance, like a moto cross bike. The muffler if tune correctly would be the expansion chamber and if the outlet is too big the power band would be lost.

Steve

 

[Cease232]

Been tests done here that show power actually increases indefinitely as the size of the muffler outlet increases. Gains drop significantly at about 85% while decibels increase. If your really that worried about it buy a few aftermarket mufflers do various mods and report back.


Sent from my iPhone using Tapatalk Pro

 

[Johnnybar]

Been tests done here that show power actually increases indefinitely as the size of the muffler outlet increases. Gains drop significantly at about 85% while decibels increase. If your really that worried about it buy a few aftermarket mufflers do various mods and report back.
Sent from my iPhone using Tapatalk Pro

Thanks for the input but the whole purpose of this thread is to not do what you are suggesting...it has already been done many times by very knowledgeable saw shops and modders that know exactly what they are doing. I'll be patient and get their input so I can get it right the first time.

 

[Cease232]

I gave you the answer. . . 85%. . .theres no magic recipe as everyone's definition of what works best is different. Unless you put the saw on a dyno you'll never know and it'll still just be someone's "opinion" read 100 threads and you'll get 100 conflicting opinions. I hope you find what your looking for though.


Sent from my iPhone using Tapatalk Pro

 

[Jed1124]

Take the muffler off. Under the front cover plate is a dimple. Use that dimple as a pattern and cut it out. Put the front cover plate back on with the muffler. No one will ever know from the appearance of the muffler anything was done.
I've done this to quite a few 290,310,390 saws. I've checked the before and after rpm jump on them and it averages to about 1k jump in rpm. You will have to richen the H side accordingly to bring the rpm down to an acceptable range. I think the book is 12 500-13 k on these saws but it's been a while.

 

[Johnnybar]

I was referring to the last part of your response:

If your really that worried about it buy a few aftermarket mufflers do various mods and report back.


Sent from my iPhone using Tapatalk Pro

 

[Cease232]

I was referring to the last part of your response:

It's cool, I'm not trying to argue. What works for some may not work for you. Some people want every ounce of power possible, some hate loud mufflers, and some try to find a balance between the two. I tend to fall into the latter.


Sent from my iPhone using Tapatalk Pro

 

[Johnnybar]

The 85% figure was not specific to know what to do with it. Is that the area of the baffle tube openings, the muffler exits or the diverter cap port/s?

 

[TreeJoe]

The 029 is a tuff little saw. Little heavy but so are most people.

 

[TBS]

You need to be less than 85% of the exhaust port size on the cylinder.

 

[Bedford T]

i finally ordered another muffler yesterday from huztl http://www.huztl.net/Muffler-Exhaus...0-029-039-Chainsaw-1127-140-0601-p228142.html with new hardware http://www.huztl.net/Muffler-Hardwa...1601-1127-149-0650-1127-148-1200-p228143.html and i have a piece of screen to cut https://www.amazon.com/Stainless-Steel-Type-Mesh-Diameter/dp/B001CTV5WU and this is the way i am modding mine. my muffler i could not bring myself to mess with it. i will put it on the shelf and if i change my mind i have one in excellent shape to put back on. this is the design that made the most sense to me. the hole might be the dimple jed was talking about and the cover is angled back a hair.