Muffler Mods 1/2 the story?

[one.man.band]

New Here. (everywhere else in the world i'm old).

*i have searched for 1/2 an hour on this topic......but nothing really related to what i would like to know. if its here already, sorry.*
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Saw: Husky 340e (for firewood cutting and storm cleanup)

Problem: Needs some more umph.
Another problem: Not enough cash on hand for bigger saw.

What i've done: What y'all call a muffler mod. Removed spark arrestor screen. Drilled two 3/16ths inch holes under spark arrestor screen (to the left of the existing muffler exit hole). Replaced spark arrestor screen. Removed high speed jet plastic tamper proof plastic tab extension with a razor knife. Gave high speed jet a 1/4 turn counterclockwise (just to be safe). <<<<<<<Not sure about why?

What it did: Woke it up some.

Is there more in it? Is the muffler the biggest restriction, or the air filter?

I usually work on things with 3 and 4 inch pistons.... wrenching on saws is new for me. To make more power, the most restrictive thing limiting flow/velocity needs to be addressed.

Understanding, that in a high rpm motor, like a saw, its all about horsepower. HP doesnt matter below 5200rpm. To get the horsepower up high you need to flow more air faster.

When opening the exhaust up on much larger motors a lot of low end power is lost. The lost power is made up in the higher rpms. The result is the power band moved up in rpm.

Posts i've read say to richen carb when doing the muffler mod.

When a car or motorcycle is tuned for higher rpm, using the same caburator as before, jet sizes rarely go up. More air velocity (through the same carb) pulls fuel out of the carb at a faster rate. Well tuned vehicles usually go down a size or two in jet size.

My saw tuning is not complete. I have to run the saw a while longer to see if plug color indicates a rich or lean condition for my muffler mod. First indication is that 1/4 turn richer is blowing blue.

Has anyone modded the air box/carb along with exhaust? What parts are interchangeable?

 

[nmurph]

You can open the total muffler opening to 90-100% of the size of the exhaust port at the piston wall. To measure, take a handful of spaghetti noodles (yes, uncooked) and stick as many of them as will fit against the piston. Remove and measure. You can go larger than 100%, but the performance return starts to decline after about 90%.

 

[one.man.band]

nmurph...... thank you for the great info!

Will do.

Locktite blue (medium strength) on the threads?

Anything that helps me and my saw from bogging down...... while cutting up a 34 inch ash trunk .......without raising my blood pressure from frustration is a plus!

is asking this baby saw to run 7+ hours in a row without a cool down too much?

put some major hours on it....definitely not babying it. though, if i knew 4 or 5 years ago when i bought this thing that rebuilds were basically out of the question, i would have never bought it.

 

[flushcut]

Try keeping the rakers a little higher and the chain sharp that way the saw is taking a smaller bite while keeping your R's up through the wood.

 

[ratso]

The saw you have is not designed to run 7hr a day and cut 34" wood.I don't care how many mods you do it will not work.I would sell it and get a 70 cc with that big of wood 34" 90cc is better.

 

[scottr]

A muffler mod is half the story but the other half of the story is that you need to retune the carb.

 

[one.man.band]

appreciate the feedback on this.

Since tuning the carb.....almost two tanks of fuel through it adjusting low and high speed jets......(cutting not just spinning the chain in the air).

i found out that it likes it an 1/8 turn leaner than stock the best. plug color is actually what i wanted to see. had color but not dark.

tuning this thing for plug color is cumbersome.

the way i always do it for (dirt bikes, mc and cars): clean off plug using propane torch and dipping in water.....adjust jetting ....run with load......shut off immediately .......check color....repeat

with the saw...lots of reversion back into cylinder....plug color changes quickly. muffler system is not very efficient...even with extra holes.

as far as power increase....hard to tell for sure....think i gained a touch.... but no way to really be sure.

what the saw definitely does now after drilling muffler: saw revs up quicker.... is louder.....and puts off way more heat on my top hand. after running saw about 1 foot into a 14" ash log the plastic cover was melting above the muffler under the handle.

i dont care how the saw looks, but i now have to get my welder out, cut and bend some 16 guage steel and tack it on top of the muffler to get divert of all the heat. another thought is....why in the world does the stock muffler exit point up towards the handle anyways? gotta chuckle.

things i learned:
like ratso says. 'your saw no matter what mods you do ........ (true very true)
like flushcut says .'keep rakers low...... (true very true)
not sure if scottr read my original post (but is right)


what i say is ......muffler mod on my husky 340e was of not much help concidering the time and extra work involved. saw is just too underpowered for what i have/want to use it for. (kind of like hotrodding a louder Yugo).

use it till it breaks for good.

hope someone besides me got something out of this thread.

 

[xdmp22]

This may help too


http://www.arboristsite.com/chainsaw/174660.htm

 

[JustinM]

The saw you have is not designed to run 7hr a day and cut 34" wood.I don't care how many mods you do it will not work.I would sell it and get a 70 cc with that big of wood 34" 90cc is better.

+1

Rather than spending all that time trying to mod your 340e Id be spending as much time as possible looking for a great deal on a used saw.
Get up extra early on the weekends & hit as many yard sales as you can. Read all the papers, scour craigslist etc.

Ive managed to buy at least 10 saws over 60cc that for less than $100 each. It takes patience but you can find some gems out there if you look hard enough. Good luck.

 

[sunfish]

Muff mod shouldn't melt the top cover and heat your hand up. You need to look at all the muff mod on here. I put an extra port on the chain side with deflector blowing exhaust forward.

Keep the little guy and get a larger saw. I have 4 more saws than I did when I found this site, just over a year ago.

 

[russhd1997]

New Here. (everywhere else in the world i'm old).

*i have searched for 1/2 an hour on this topic......but nothing really related to what i would like to know. if its here already, sorry.*
********************************************************

Saw: Husky 340e (for firewood cutting and storm cleanup)

Problem: Needs some more umph.
Another problem: Not enough cash on hand for bigger saw.

What i've done: What y'all call a muffler mod. Removed spark arrestor screen. Drilled two 3/16ths inch holes under spark arrestor screen (to the left of the existing muffler exit hole). Replaced spark arrestor screen. Removed high speed jet plastic tamper proof plastic tab extension with a razor knife. Gave high speed jet a 1/4 turn counterclockwise (just to be safe). <<<<<<<Not sure about why?

What it did: Woke it up some.

Is there more in it? Is the muffler the biggest restriction, or the air filter?

I usually work on things with 3 and 4 inch pistons.... wrenching on saws is new for me. To make more power, the most restrictive thing limiting flow/velocity needs to be addressed.

Understanding, that in a high rpm motor, like a saw, its all about horsepower. HP doesnt matter below 5200rpm. To get the horsepower up high you need to flow more air faster.

When opening the exhaust up on much larger motors a lot of low end power is lost. The lost power is made up in the higher rpms. The result is the power band moved up in rpm.

Posts i've read say to richen carb when doing the muffler mod.

When a car or motorcycle is tuned for higher rpm, using the same caburator as before, jet sizes rarely go up. More air velocity (through the same carb) pulls fuel out of the carb at a faster rate. Well tuned vehicles usually go down a size or two in jet size.

My saw tuning is not complete. I have to run the saw a while longer to see if plug color indicates a rich or lean condition for my muffler mod. First indication is that 1/4 turn richer is blowing blue.

Has anyone modded the air box/carb along with exhaust? What parts are interchangeable?

Only drilling two 3/16" holes in your muffler isn't opening it much over stock. I have an MS290 Stihl and I opened mine up about 90% like nmurph said. It made a big difference on my saw. The spaghetti trick works good for measuring how much you have taken out.

 

[sunfish]

Yeah, two 3/16" holes wont do it. We need to see a photo of this MM.

 

[one.man.band]

to be clear..... i did not open muffler exit hole to 90% ex. port size. the results i listed are for 2 additional 3/16ths inch holes.

why did i originally pick 3/16ths drill bit and two holes?
1. beacuse if i used a larger diamenter drill bit.... it would not fit beside the existing stock exit hole .....while the exhaust diverter metal shield was attached to the muffler. i did not want to cut it off and tack it back on with my welder. i drilled the holes without taking the muffler off of the saw.

2. stock muffler exit size is approximately 1/2 inch. (i eyeballed it. didn't put the dial caliper on it). now the screen is back on and since i had metal burrs from drilling...the screen did not go back on without some tweaking.
the holes: 2 @ 3/16ths holes = 6/16ths = 3/8ths. i gained effictively 75% more exit hole than what i had. (3/8 to 4/8=1/2).

3. spaghetti is a great idea....never used it though. i have the calipers. sadly didn't measure port because i got a break in the weather to finish sawing wood.

4. if there is not enough room for the welder between the handle and muffler to weld a heat shield on there ....i'll pull the muffler.....measure the port and work closer to 90% of exhaust port. its alot easier to take metal off than to put it back on. money is tight....i would rather spend money on chains than mufflers.

5. nmurph never said what kind of saw he did this to. i dont know nmurph, seems like a good guy, appreciate advice.....and look forward to more. but in the end its my saw. its not how much you take off...its how much you actually leave on. more than enough porting is much worse than less than enough. learned that the first time i ruined a set of ironhead sportster heads. paying tuition for a set of heads makes you learn real quick. what works on one head does not always work on another.

 

[PogoInTheWoods]

Wrong saw for the job, mang. Period.

And the other 1/2 of the MM story is why you really need to richen the H....

....to keep the saw running as cool as it needs to for all that leaning out ya just did by opening up the air flow -- which was at the exhaust port, not the intake. 'Course as stated, a coupla 3 stinks holes isn't exactly a MM and probably didn't affect the overall performance aspect very much at all or even need the carb richened much.

And you tune these little 2 stroke rascals by ear, not by the plug color.

But ur sure as hell in the right place for learning what ya need to know as ya head down the road with your project(s)? -- which will multiply the longer you hang around. Trust me.

Welcome aboard.



Poge

 

[PogoInTheWoods]

New Here. (everywhere else in the world i'm old).

Oh, yeah...

"The older ya get, the better ya were." :msp_thumbup:

 

[Chris-PA]

Wait, is this the muffler shown at the bottom here:

<img src="http://c.searspartsdirect.com/lis_png/PLDM/P0512006-00003.png" width="800" height="1038" alt="503862803" />

Did you drill the holes pointing up at the cover?

 

[RiverRat2]

More saw!!!!

35" wood is 70+CC saw material,,,BTW,,,, That saw for 7 hrs in 30+" wood??? as others have stated,,,, good luck,,,,

you are in the Still 440/441/460 class or Husky 372/576/390XP or DOLMAR/Makita 6400/7300/7900 class of saws,,,,,,

what yer trying to do is alikened to a Pi$$ ant pulling a bail of hay!!!!! A MM for any saw is cool,,,,, but in this case you need another 3.5 Cubic inches of displacement

Dont mean to rag on ya,,, but what you are asking doesent make much sense.... oh an for your mm Re-tune you need to come open on the L screw as well @ least 1/4 turn especially if you open the muffler any more than what u have,,,, just opening the H is not gonna cut it,,, If you dont I will be surprised if that saw makes 7 Hrs in 30" wood,,,,

Just sayin

 

[one.man.band]

*thanks again yall for giving advice.
*thanks pogo for the welcome.

the muffler in question is the bottom one in the photo. wish it was one of the other 2 shown. i did not cut it in half..so i dont really know exactly what kind of baffles are in there. yes..i drilled the holes into top cover.

it started right up as usual...so i only tried monkeying with low speed screw for first two starts. could not tell any difference. good catch RR2

not sure how the carb meters fuel? does it all go through main and only idle through lowscrew? or is there an air bleed in there to fiddle with too?

i dont go after 34 inch ash. this particular one went after me. remanents of a tornado storm that hit about 5 miles west of here decided to knock down this tree, and take 1/2 of a 35 foot blue spruce down for me. my usual cutting does not include knocking things like this down. unfortunately i have many willow trees that are much larger than the ash was. i cut all the willows down that my 18 inch blade could handle. but there are monsters still left.

began this thread out of muttering frustration in the saw. was searching internet to try to make it better and ran accross this site. kind of heavy for limbing....too light for throwing chips out of the big stuff. like mentioned before..if i knew then what i knew now.. 2 saws would be much better than a single saw.

Now i know.....and i wish i didnt!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

hahaha

 

[sawinredneck]

First, pull the muffler off and see what kind of baffles are in it and drill through them, big as you dare, size doesn't matter until you get to the exit.
Sounds like you have some decent mechanical abilities, and tools, take a dotco or other grinder and enlarge the exit properly.
THEN tune it, I think you will be surprised at how much that wakes it up!
Finally, SHARP chain, SHARP chain and SHARP chain! Mod that saw all you want, but if it's making dust it doesn't matter how good it's running!
Yes, the saw is under sized, but yes, it will do it and yes, I understand making due with what you have!
Good luck with it!

 

[PogoInTheWoods]

*thanks again yall for giving advice.
*thanks pogo for the welcome.

the muffler in question is the bottom one in the photo. wish it was one of the other 2 shown. i did not cut it in half..so i dont really know exactly what kind of baffles are in there. yes..i drilled the holes into top cover.

it started right up as usual...so i only tried monkeying with low speed screw for first two starts. could not tell any difference. good catch RR2

not sure how the carb meters fuel? does it all go through main and only idle through lowscrew? or is there an air bleed in there to fiddle with too?

i dont go after 34 inch ash. this particular one went after me. remanents of a tornado storm that hit about 5 miles west of here decided to knock down this tree, and take 1/2 of a 35 foot blue spruce down for me. my usual cutting does not include knocking things like this down. unfortunately i have many willow trees that are much larger than the ash was. i cut all the willows down that my 18 inch blade could handle. but there are monsters still left.

began this thread out of muttering frustration in the saw. was searching internet to try to make it better and ran accross this site. kind of heavy for limbing....too light for throwing chips out of the big stuff. like mentioned before..if i knew then what i knew now.. 2 saws would be much better than a single saw.

Now i know.....and i wish i didnt!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

hahaha

Oh, yeah. You're in for good, now!

BTW, (whispering) it's a bar and chain, not a blade. Shhhh.

:hmm3grin2orange:

Poge