660 Dual Port Muffler Mod

[hautions11]

I know this has been covered a few times, but I wanted to show another dual port method that I did not see anywhere else. This is a 2005 660 with all of the restrictions and EPA stuff. My first idea was to steal a dual port muffler off my 064 and put it on the 660. No go. The older muffler was actually taller, so the outside mounting screws had a 1/4" gap back to the case. This dual port is not the standard hole in the cover you normally see on Stihl factory dual port covers. This muffler has an oval slot in the main body with a deflector and spark arrestor screen. I then decided to cut up my existing muffler and make it look like the old one. I wanted to maintain a relatively stock looking set-up. I started by drilling a bunch of holes in the inner baffle. They are similar in size to the 064 muffler. I then drilled two holes to make the slot on one side of the main muffler body.

Note the two holes right side of the main body. The normal exit hole in the main body was quite small, so I enlarged it to roughly the size of the old muffler. I connected the two holes to make my oval slot.

Here is an inside and then outside view of the mod.

The muffler mounted back on the saw. Real clean.

I kept my fairly stock appearance and the sound is nice without being too loud. Tommorrow I will remove the carb stops and richen it up a bit. Is this really an old factory dual port or just someones early mod? Comments?

 

[fishhuntcutwood]

That's someone's mod. Factory dual port is via the cover.

 

[Justsaws]

Got carbon? Why yes, I make pencils on the side..

Do not go to rich. Carbon scoring is still scoring.

Might want to take a peak at the top of your piston. Muffler mod looks like it should free up some breathing. Might want a bigger deflector. See if it puts any exhaust on the expensive parts, go from there. Looks good. Good luck.

 

[RiverRat2]

I think FHCW is definitly correct, its not and early factory dual port,,,,,
But it should work fine maybe a bigger deflector would be better,,,,,


Good work and nice pix, How the new saw run BTW it got all of those trees down with no problem I would think????

 

[hautions11]

My old muffler had an additional piece of sheet metal brazed to the original deflector, I may fab something up. The saw runs real nice. Good power, starts easy, idles good. I think my 064 is almost as strong and I noticed the 660 fell off the power band a little quicker. I want the muffler mod to give it a little more grunt across the board.

 

[Lakeside53]

That's how the old 064 DP was done... The later 064DP was the same as the 066. You just need to delete (or add, I forget) the $3.20 spacer...

 

[hautions11]

Lake it must be add the spacer to the 064 muffler. Is that a factory part? $3.20? Is it a spacer under each of the 2 screws or one piece across the top that catches both?

 

[Lakeside53]

Lake it must be add the spacer to the 064 muffler. Is that a factory part? $3.20? Is it a spacer under each of the 2 screws or one piece across the top that catches both?

The spacer I'm talking about sits with a gasket on each side between the muffer and the cylinder.. Looks lust like a 3/16 thick gasket. It's on the old 064 IPL.

 

[hautions11]

I looked on my IPL. That spacer would let the shorter 066 muffler work on the 064. The 064 is still too long to go on the 066 or 660.

 

[fishhuntcutwood]

That's how the old 064 DP was done... The later 064DP was the same as the 066. You just need to delete (or add, I forget) the $3.20 spacer...

You mean those sheet metal screws holding it onto the side of the can were factory?

Got me there.

 

[hautions11]

I cut with it this AM. 28" ash meets 28" bar. Much nicer. A little throatier exhaust note, but not too loud to be obnoxious. Overall, I am very pleased. A little tuning is next.

 

[RiverRat2]

You mean those sheet metal screws holding it onto the side of the can were factory?

Got me there.

my bad, it is rather factory looking just kinda short but it should work fine!!!!

 

[Cut4fun]

I like the looks of that extra twin vent deflector. Wonder what that vent is off of?

 

[hautions11]

Cut4fun, I thought the same thing. The screws look funky, but the vent is real factory looking. With that vent and some stainless screen, you could convert any muffler.

 

[stihlatit]

From the picture te vent looks close to the brake bar. Watch for melting plastic. Others may be right in extending vent.

 

[hautions11]

There is actually an inch or more. It ran on my 064 for years without any issue. The clearance is similar.

 

[oldsaw]

From the picture te vent looks close to the brake bar. Watch for melting plastic. Others may be right in extending vent.

Arnie is right on that. My similar 2nd port failed and I burned a nice chunk off of my chainbrake handle. Make sure you are getting the heat deflection you need.

Mark

 

[fishhuntcutwood]

OK, so is that LH side vent with the louvered deflector factory? I'm all screwed up here...:help:

 

[RiverRat2]

I thought Lake said it was for an 064 but there is a spacer of some sort that goes with it?????

 

[hautions11]

Just to clear up the spacer issue. The 064 muffler is longer then the 066. IFFFFF you put the shorter 066 muffler on an 064 you need a spacer between the muffler and the cylinder to space the muffler out to meet the case mounts on the top 2 bolts of the muffler. Has nothing to do with the dual port. The louvers direct the exhaust gasses away from the saw and the chain brake handle.