Modify Saw Muffler .... is It Worth It or Not and How To Do It ? ? ?

[H60 Hawk Pilot]

I Just did a Search and Noticed Different Ideas.

I have a couple new (681 Solo & Efco 251) saws and they cut fine and just looking for a little more HP if it's worth it by a simple modification  by  reducing muffler restriction.

Years ago, we'd drill holes in the baffles or removed part of of the muffler guts and it seemed to work... was louder for sure.

From what I read here (FF), they use dual port mufflers for better power. I see the baffle hole drilling trick is still around and baffle modification as well.

I'm not looking to get too carried away with a muffler mod. but if >>  05% + power was realized for a simple type modification... I might be interested.

The Solo 681 is  Not a CA  type saw but the Efco 251 has some emission stuff;  I have to re-read the 251 operator manual to see what it has (forgot).

I understand with all mod's. >>  carb. re-tuning is required and that's a given for any changes to any engine with >> fuel or ign. changes.  What I don't need is... a hole in the piston from making too much of a change and messing up a good saw.

Thank Ya'

Avery

 

 

[ladylake]

 I think you'ld see good gains on the Efco with a clogged up muff stock, The Solo is kind of a factory hot rod, they most likely have a free flowing muff already.   On my little 40cc Echo CS400 cut times went from 15 seconds to 9 seconds with a muff mod, that had a choked up cat muff.  Turned in to my favorite saw around the mill.  Steve

[Cut4fun]

I would leave the Solo 681 alone. She's hot right out of the box.

[Al_Smith]

As long as you can tune the carb so it has that "4 cycle " sound ,you are safe .If however you can't get enough fuel you take the chance of turning the piston /cylinder into crispy critters .

My favorite example happen a few years back .A certain person who owned a tree service in Cincinati got some info from the net about modding a muffler,so he did and was proud as a peacock about his brand new 088 Stihl . Ran like a scalded ape .

I cautioned him about it but this expert engine man from Canada assured him that a  giant hole in the muffler would be just fine .Well of course the old farm boy doesn't know anything, so I shut up about it .

Sure enough up on flea bay pops a brand new 088 Stihl, cooked top end . That was  about a thousand -1200 dollar boo boo at that time .

[John Mc]

Someone once posted some guidelines about the area of the muffler exhaust port as compared to the exhaust port area coming from the saw. I can't remember what they said, but perhaps one of our resident saw gurus could give us an idea...

John Mc

[John Mc]

Another thought, Avery...

I'm not sure how worried you are about warranty coverage, but if these are new saws, you may want to wait a bit, or do this in a way that's easily reversible. If you are in an area where fire is not a major concern, you could just pull the spark arrestor screen for starters and see how that works, or maybe buy an aftermarket muffler to do your mods on, keeping your original muffler to swap back in if you had a warranty claim.

I still have the catalytic muffler I took off my Jonsered 2152. I wasn't nuts about fiddling around with some of the nasty metals inside without knowing more about what precautions to take, and I figured I had something to go back to if I didn't like the results. I never did get around to modding the non-cat replacement muffler. Just the swap solved my heat problems and gave a noticeable boost in power. I may try it some day.

[Jeff]

Or you could run them stock which is suitable for 99.9% of the population that don't primarily run a saw for a living.  You are building a log house and using a sawmill. You don't have log production as a concern to a paycheck at the end of the week. Leave em alone.

[Al_Smith]

Or you could run them stock which is suitable for 99.9% of the population that don't primarily run a saw for a living. 

--and that remaining  tenth of one percent has 5,000 secret formulas of how to do it .

[John Mc]

I'm generally part of that 99.9%. However, in my case, I was having trouble with my 2152 overheating. It would run just fine for a full day of felling (generally time to cool off between cuts, or lighter loads when limbing). When bucking hardwood for firewood, it would run OK for a couple hours, then stall and have trouble starting again unless I let it cool down first.

I didn't know much about tuning at the time, but wondered if it might be running too lean. I took it to a shop with a good reputation for service. He thought it was set up just fine. At the suggestion of someone here of FF, I swapped out the catalytic muffler for a non-cat one, and rechecked the mixture. All of the problems disappeared. The bit of power boost I noticed was just the icing on the cake. Plus, doing this finally got me off my butt and learned how to set the mixture myself.

John Mc

[smith2bj]

So hearing all what you guys are saying about porting, do you thing that this would be something that is worth doing to my 2171?  It about a year old and if I can get some more power I definately want to do it.  But I dont what to smoke my saw.

[Cut4fun]

2171 muffler is a open can, no baffle inside. Never muffler modded a stock one to see if there was any gains. Never felt I had to on stock being they seemed to breath pretty goo the way they were.

Now on the woods ported ones muffler modded with dual ports using a husky deflector on the side or going through the front brace on front of muffler. Try it on a stock one and let us know. Dont forget to adjust carb and cut plastic stops on L and H to get full adjustments. 

There you go have at it. 

[Al_Smith]

So hearing all what you guys are saying about porting, do you thing that this would be something that is worth doing to my 2171? 

Now don't get the term "porting " confused with reworking the port scheme of a saw engine as opposed to just relieving the pressure on it's muffler .However to get the former to work properly you will have to do the later .Kinda like the chicken and the egg .

[Ax- man]

Someone once posted some guidelines about the area of the muffler exhaust port as compared to the exhaust port area coming from the saw. I can't remember what they said, but perhaps one of our resident saw gurus could give us an idea...

John Mc

I might as well get in on this thread. Enlarge the exhust muffler exit hole about 80 to 90% of the exhaust port.   After that there is really no noticeable gain in power. I have used that guideline for any muffler mod I have done to a saw, plus the the retuning, no problems . Just readjusting your low speed screw alone to provide a richer mix isn't a hard and fast rule. I have had to fiddle with the high speed jet also to find that sweet spot after doing a muffler mod. I like to to make a nice long rip cut or cut a big diameter hardwood log after doing a muffler mod. If the saw falls off in the middle of the cut or dies after making the big cut it is still lean and needs to be richened up. Starting up by the fourth pull is a good sign your close to the right setting. A nice clean acceleration with no bogging or stumbling is another good sign but it is the cutting that is the best test.

A well done muffler mod along with a sharp chain is more than enough to get that extra power kick from a saw. I try not to gut mufflers out but more enlarge baffle holes or add a few holes in the baffles and try to keep the same flow of the exhaust just not so restrictive as a stock muffler. Enlarging the exhaust hole in the muffler is usually enough to get the job done. I also prefer to leave the screens in as I personally don't see them as being restrictive. I know someone will argue this point but that is just my two cents on the subject nothing more.

[H60 Hawk Pilot]

Thank You  Ax-man

You spelled it out fairly well. I'm a big engine builder (diesels) and love engines in general. The little Efco 251 is a fair saw, I'd just like to give it a boost by a simple muffler modification &  understand 80/90 % of exh. port is my guide line. I have a Fuel/ Air Mixture Tester that I bought to set the carb. on a 460 Ford engine that I rebuilt (installed new carb. & intake) in a motor home.

I might use F/A tester on the little saw for tuning but the best test is under power as you mentioned. I remember the best power mixture as 10:1 (by memory) for best power, also the exh. flame is >> deep blue/ purple at best power. Orange or Red color is lean or too rich. I realize that the exh. flame is not visible with the muffler on. I have used this method on race engines and aircraft engines with short stacks; deep blue color does not lie.   

I fired up my Dad's Homelite XL12 a few days ago. The XL12 (old but like new) cuts super and the added noise did not bug me at all. I can't imagine why they smog a little (Efco 251) chain saw like this and I'm 3000 miles from CA... just nuts. I lived in CA in the 80's (4 years) and have met some extreme folks in CA & (overall) common sense is not their stong suit. Lot's of far left or right, not a lot of center fielder's; just my personal opinion, maybe I got it wrong  .

Thank's

Avery

[Frickman]

I'm with Jeff, leave it alone. I earn my living running a saw and have never modified a muffler. If I want to cut faster I just buy a bigger saw. I only remove the spark arrestor screen, that's all. The saw maufacturers have designed their saws to run as efficiently as possible as long as possible. When you start deviating too far from their design you end up destroying saws.

[ladylake]

 I'm for the muff modd, most new saws are way choked up thanks to the EPA. Bigger saws weigh more, it's nice to have added power out of a lighter saw.   Steve

[wickmar]

   In my experience, spark arrestor screens tend to plug up with:   1) Time  2) Too rich a carb setting  3) Too much oil in gas.   Seems like just removing the screen will solve PART of the problem.   Otherwise a carb adjustment and maybe running a quality syn. premix oil would help.   Then you wouldn't have to deal with the expense and potential upper end problems of a muffler mod.
   Just a thought.

         wickmar

[welderskelter]

I have an 066 Stihl that needed something and I just found a muffler that was off an older saw. Before EPA, Ha. I will bet I gained about 25 to 30 percent more power. Lots louder but runs like a raped ape. I took it in to have the settings checked and he said they were fine but give them a final adj. Best thing I ever done to that saw.

[H60 Hawk Pilot]

Welderskelter

I'm with you (mod. exh.) and plan on opening the exhaust up in the next few days. Today, I cleaned all my saws, removed the bars and blew all the saw dust out, air cleaners... the works. I did take alook at the exh. and it's really thick and looks real busy in there and jam packed & lot's of restriction and back pressure.

If I get a  25% +  boost in HP I will be smiling big time  .  The Efco 152 is a fair saw (as it is) and cuts decent with the micro chain set up (not the anti kick chain). I bet with a little modification, she'll run real decent like your Stihl 066 (raped ape).

I think most of the guys are lost whem it comes to mod's. and tuning and rightfully so if they never did this type of work.

Thanks' for the Information. 

I'll let you know my result's when I get her mod'd. up.  I will see how much crapp is in there and go from there.

Avery
     

[weimedog]

I'm a hack..not a saw builder by any stretch of the imagination! So the following are things a typical "hack" can do to have a little fun...DON'T play these games unless the saw is essentially expendable! And certainly re tune the carb if you do anything that might effect flow in anyway. (Last but not least...if its a real working saw, a larger tube with a spark arrester screen inside might be the appropriate thing to do..especially if you work in those dry places where forest fires are possible!)

I mod the mufflers on my hobby saws...and if the saw will be used as a real 'working in the woods' saw...I usually plug all the stock outlets, gut all the internals and for the 70-80cc class cut a hole in the corner towards the clutch/chain brake side and weld or braze in a 3/4inch tube. The mods I have done going straight out the front of the muffler, whether it be a simple enlarged hole, or tube; turn into liabilities when I rock the saw & therefore outlet of the muffler into the wood! The side exits aren't bothered by real work as much. And for a real working saw; don't forget a spark arrester screen..mine are usually on the inside.

A 365 with a 371 cylinder & aftermarket piston...stock ports, just muffler mod and no base gasket (Tri bond 1194)..out runs my woods ported 272XP...if you ever put the 272 and 372 cylinders side by side you would understand. 372 has so much more port area stock than you can even hog out of a 272 without getting real creative! (The true builders can do things I can't)



An in process mod for an old Jonsered 920, Split it open and removed all baffles leaving only the support tubes the mounting bolts go through. Brazed a 3/4 inch dia. tube for the outlet. Also brazed it back together and then ground the rough spots away for looks and painted it black with high temperature resistant paint.




A NOT very practical mod I did for kicks on my GTG fun Saw...It makes lots of noise and cuts pretty fast for what it is..but not practical for a working saw! (Mildly ported 2094 assembled with no base gasket and has stupid compression as a result!)



Last but not least, a muffler mod on a ported 272 done by a local saw builder..and its much faster than stock  only a bit faster (maybe!!) than my basically stock 371 cylinder on a muffler modded 365! Message? A well designed saw stock may still kick butt on a similar sized home modded & ported saw!