660 exhaust question?

[BostonBull]

I took the exhaust apart on my 660 and was wondering when I put the Dual Port front cover on should I cut out the baffles in the muffler also?

 

[Hired Gun]

Bull are you going to leave the little hole in the side alone or are you going to hog it out? I was thinking about that today too. I will have a 660 shortly. Are you happy with the saw so far. I see that seller moves a few of them.

 

[Cut4fun]

Gut it (remove the baffle) and dual port cover, just my 2 bits.

 

[rahtreelimbs]

I read somewhere that all that should be done is to cut the bottom out. The internal box adds rigidity to the muffler.

As FHCW said open the stock port up also.

 

[Lakeside53]

If you do, just drill out the UPPER portion at the back of the box - the lower portion doesn't go though!

Not sure it make a whole heck of a lot of diff though...

 

[rahtreelimbs]

Andy, you intrigued me with the fact that you figured that the 361 had more than enough hole area in the internal box. How did you figure that one?

Also what of the 660..........in the same manner?

 

[Lakeside53]

Measured all the litle holes, figured the areas, and then added...


I never did calculate the 660. I ran mine for a few month with the box in, then drilled out the top back, and I'm not sure it made a difference (I didn't need to re-adjust the carb after drilling) except it got louder. And it's already LOUD!

 

[Lakeside53]

.

As FHCW said open the stock port up also.

There isn't much point in opening up the stock port if you add the Dual port front - it's MANY times larger than the stock port... (I published the numbers in an old post.


If you mod the muffler, and you don't get an RPM increase at the H end (i.e., you need to richen the mixture), you're done... or you've gone too far.

 

[fishhuntcutwood]

As FHCW said open the stock port up also.

I've not touched my 660's port. I have opened the 440 and 460's dual port though. It's still pretty tiny.