Author Topic: Muffler Mods  (Read 207 times)

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Offline The Ripper

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Muffler Mods
« on: January 17, 2014, 07:35:26 pm »
When doing M/Ms, what are you doing with the internal diffuser/baffle,are you eliminating it or enlarging the holes? I 've seen some pictures of this mod but have searched with no luck. The exhaust outlet opening will  be a tube of either 3/4" to 1" for the 3.7 just need to see how the saw responds.

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Offline Eccentric

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Re: Muffler Mods
« Reply #1 on: January 17, 2014, 09:48:29 pm »
I drill the holes in the diffuser larger (and add more holes).  I also retain the spark screen, as I cut in places that require them  (and that design gives a huge amount of screen area anyways).  The diffuser is also a support for the muffler shell.  Allows you to put good sealing pressure on the exhaust gasket without crushing/distorting the muffler can.
-Aaron

For older saws:
Tune the H side so that it 4-strokes (burbles) at WOT unloaded and just cleans up when under load.
When you lift cutting load, the saw should immediately revert to 4-stroking.  Fine tune the transition point for the wood you're cutting.

Offline 3000 FPS

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Re: Muffler Mods
« Reply #2 on: January 17, 2014, 11:25:45 pm »
I just take a hand held cut off saw and cut the center out of the diffuser about half way.  I do both side of the diffuser.   I leave the two tubes attached where the screws go thru and then put it back together with the spark screen.   Like Aaron I cut in areas that require it by law.
PP 505, 475, 445.

Offline Eccentric

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Re: Muffler Mods
« Reply #3 on: January 18, 2014, 12:17:58 am »
With this style of muffler (with the screen wrapped around the diffuser), there is a huge amount of screen surface area.  That much screen will give less restriction than the outlet on the can, even once the outlet hole is enlarged.
-Aaron

For older saws:
Tune the H side so that it 4-strokes (burbles) at WOT unloaded and just cleans up when under load.
When you lift cutting load, the saw should immediately revert to 4-stroking.  Fine tune the transition point for the wood you're cutting.

Offline 3000 FPS

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Re: Muffler Mods
« Reply #4 on: January 18, 2014, 12:20:04 am »
With this style of muffler (with the screen wrapped around the diffuser), there is a huge amount of screen surface area.  That much screen will give less restriction than the outlet on the can, even once the outlet hole is enlarged.

Very good point Aaron on the spark screen.   That spark screen is one of my favorite type of designs.
PP 505, 475, 445.

Offline Eccentric

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Re: Muffler Mods
« Reply #5 on: January 18, 2014, 10:45:52 pm »
With this style of muffler (with the screen wrapped around the diffuser), there is a huge amount of screen surface area.  That much screen will give less restriction than the outlet on the can, even once the outlet hole is enlarged.

Very good point Aaron on the spark screen.   That spark screen it one of my favorite type of designs.

Mine too.  I couldn't help but notice (while muffler modding a 54cc PP330) that they have at least 5x the screen area as on the muffler of a 94cc 395XP.8)
-Aaron

For older saws:
Tune the H side so that it 4-strokes (burbles) at WOT unloaded and just cleans up when under load.
When you lift cutting load, the saw should immediately revert to 4-stroking.  Fine tune the transition point for the wood you're cutting.

Offline 3000 FPS

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Re: Muffler Mods
« Reply #6 on: January 18, 2014, 10:51:11 pm »
Even more than my Husky 2100CD.
PP 505, 475, 445.

Offline The Ripper

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Re: Muffler Mods
« Reply #7 on: January 19, 2014, 09:10:11 am »
Found some muffler mod info from here and another forum. Will try and post pictures when the time comes,if I can. We have a Mac and for some reason it won't acknowledge our camera for up loads >:(

 

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