Chainsaw Repair

Husqvarna - Stihl - Poulan - Jonsered - Dolmar chainsaws and more => Poulan => Topic started by: Cut4fun . on October 17, 2016, 04:18:43 pm

Title: Poulan muffler mod
Post by: Cut4fun . on October 17, 2016, 04:18:43 pm
I've tried many different muffler mod on these style of poulans over the years. But after watching the hot pattern on this 365 for awhile now I wanted to try this one.

365 just had baffle drilled out and no screen with oem exit.

I have done removed baffle with just 5/16 (thinking that maybe one smaller) holes drilled along the bottom rectangle indention.  That one allowed front to be over tightened at times and if you were right on dry wood the exhaust was right on the wood.

I have tried the dual port on right side with and without the baffle.  But still would see that hot area in center of front muffler with baffler even drilled out.

(http://i59.photobucket.com/albums/g289/doemaster789/PP325/3450390025001.jpg)


New one I am trying.

365 now has a front dual port in middle exiting to the right. Seems to be working perfect and not blowing forward in testing.  You can see where the white hot area is in center of the front muffler cover even with the baffle drilled out.
Later on I will paint the muffler cover and see if it takes away that hot area now.  Like the flow the muffler is giving me now too.



Title: Re: Poulan muffler mod
Post by: Efisher26 on October 17, 2016, 05:49:18 pm
Does timing need to change since there's a lot less back pressure?


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Just a home owner that likes the older better made machines

Craftsman 3.7
Echo 290evl
Title: Re: Poulan muffler mod
Post by: Cut4fun . on October 17, 2016, 07:20:10 pm
I dont mess with port timing or flywheel timing.   All stock.

Carbs need retuned to most muffler mods though.
Title: Re: Poulan muffler mod
Post by: Efisher26 on October 17, 2016, 10:55:50 pm
I drilled out my diffuser but was told if I replaced it with sleeves I would need to adjust timing, should I still try it?


-•------------------------------------------------------------


Just a home owner that likes the older better made machines

Craftsman 3.7
Echo 290evl
Title: Re: Poulan muffler mod
Post by: Cut4fun . on October 18, 2016, 12:16:42 pm
I drilled out my diffuser but was told if I replaced it with sleeves I would need to adjust timing, should I still try it?




I would just sleeve the bolts and then retune carb. JMO

I'm sorry but I never ever heard of retiming just because of a muffler mod. ;)
Title: Re: Poulan muffler mod
Post by: Efisher26 on October 18, 2016, 01:27:40 pm
I will have to try it then


 -Efisher26-
Title: Re: Poulan muffler mod
Post by: Cut4fun . on October 18, 2016, 05:45:34 pm
As far as the spark screen, The 365 has it pulled out. 

Some I put spark screen back on if going to be sold or traded. Also it helps line the bolts back up when installing.
Title: Re: Poulan muffler mod
Post by: 3000 FPS on October 29, 2016, 03:07:57 pm
I drilled out my diffuser but was told if I replaced it with sleeves I would need to adjust timing, should I still try it?


-•------------------------------------------------------------


Just a home owner that likes the older better made machines

Craftsman 3.7
Echo 290evl

I do not know where you heard that but you can throw the muffler away if you want and run it without changing the timing.   But like Cut4fun said you will need to readjust the carburetor.
Title: Re: Poulan muffler mod
Post by: 3000 FPS on October 29, 2016, 03:10:17 pm
I like your idea Cut4fun on the front being opened up on the muffler so that the exhaust is just a straight shot.   

My only problem would be that I still need to run a spark arrester and with that front port like you have it would defeat that on these saws.   
Title: Re: Poulan muffler mod
Post by: Efisher26 on October 29, 2016, 03:44:45 pm
I may put 2 or 3 small vents on the bottom front. Will taking out the diffuser make a difference, even after being drilled out?


 -Efisher26-
Title: Re: Poulan muffler mod
Post by: 3000 FPS on October 29, 2016, 07:03:06 pm
I may put 2 or 3 small vents on the bottom front. Will taking out the diffuser make a difference, even after being drilled out?


 -Efisher26-
If you are making vents on the front of the muffler than I doubt that removing the diffuser will make a big difference.
Title: Re: Poulan muffler mod
Post by: fossil on November 23, 2016, 01:40:20 pm
A good way to tell if there's any difference is to video a cut or two and check the time on the video.

Do a mod and cut, same sharp chain and bar, same wood. That will give you an indication of any improvement.

Louder isn't always faster. It's always good to do a timed reality check.

I don't see anyone doing that and posting it.
Title: Re: Poulan muffler mod
Post by: Cut4fun . on November 23, 2016, 08:22:19 pm
Tim's right on before and after to see if you made any gains.

I quit doing before and after videos 6-8 years ago because I already been there done that. All of this was back in the Racesaws site  days before this site.

Best I seen was 23% faster cuts with a 290 with 30min muffler mod and carb retune.  18% with the MS390. The poulans like here we are talking about are less then that.  But still gains are made with letting them breath.  I just dont care enough now days to time each one anymore.

Just like I know there is gains to be made in my 415 445 mufflers. But they cut so sweet and quite now and wont mess with them. I like quite saws myself. ;)
Title: Re: Poulan muffler mod
Post by: 3000 FPS on November 23, 2016, 10:22:00 pm
I like. My muffler mods but I should do like Tim has suggested and time them before and after.    I still like my double barrel look the best.   Just a personal preference.
Title: Re: Poulan muffler mod
Post by: Cut4fun . on November 25, 2016, 10:25:29 am
Muffler mod testing by Brian aka Timberwolfe from the past days long gone. Page 2 shows results with graphs and % of gains etc with different size opening etc. So glad I saved this info from back then or it would be lost now, with pics.

Page 1 was showing muffler mods by Roger and using spark screens.

http://chainsawrepair.createaforum.com/ported-saws/removing-spark-screens-does-it-make-a-difference/