Muffler modded my 7900 today pics

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scotclayshooter

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Hi guys well it dont even have a tank of fuel through it yet but i had some spare time this morning.
First i removed the muffler from the saw (take notes Brownpot Deaton lol)
I heated up the crimp and a bit at a time prized it up with a narrow bladed screwdriver until i coild get a hold of it with a pliers.
I did this around the bottom and one side gave it a good wiggle and the 2 parts seperated!

The baffle just fell out so i cut the complete end off and rounded of any rough edges with the dremel.
I did a quick measure and found that the area under the deflector would be as near as :censored: 125% of port area, So i cut a couple of grooves with the dremel and got a junoir hacksaw in and cut the old hole out whole lol
More tidying up and maximizing area with the dremel.
then re asembled the 2 halves bending and hammering the baffle back into place, Re fitted the screen then fitted it all back on the saw.
Now i know it has a rev limiting coil Grr i tuned it back to 13,480 so it should still be a little rich for now.
Its not much louder! and i havnt had a chance to cut with it yet, Roll on next week!

Heres the original baffle
originalbaffle.jpg


The modified one
modifiedbaffle-1.jpg


Copmare the old and new holes
oldholenewhole.jpg


And the completed muffler
completedmuffler.jpg
 
Nice work! not much louder, huh? That baffle sure looks stout. How long did it take you?
 
Nice work! not much louder, huh? That baffle sure looks stout. How long did it take you?

About an hour start to finish, O yes that baffle is strong, 0.047 and spot welded at the end! Someone suggested hammering it through with a bar but mine would have damaged the muffler before it would have bent!
Its not really that much louder not like the 036 or the FS250 (it will make your ears bleed)
The original hole was 0.557 or 14.16mm round
 
About an hour start to finish, O yes that baffle is strong, 0.047 and spot welded at the end! Someone suggested hammering it through with a bar but mine would have damaged the muffler before it would have bent!
Its not really that much louder not like the 036 or the FS250 (it will make your ears bleed)
The original hole was 0.557 or 14.16mm round

Shoot! Thats a big hole! The stock hole on the 660 was only 10mm!!!
 
The 7900 isn't near as choked up as some saws. When I muffler modded mine I simply cut the baffle up with a die grinder and ditched the screen.
This way I didn't have to take the muffler completely apart.
 
The 7900 isn't near as choked up as some saws. When I muffler modded mine I simply cut the baffle up with a die grinder and ditched the screen.
This way I didn't have to take the muffler completely apart.

That 14 mm hole must be a restriction its even flared inwards!
That cant be good for gas flow.
I was suprised to find it only had 1 piston ring!
 

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