Author Topic: 660 muffler mod  (Read 442 times)

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Offline JohnG28

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660 muffler mod
« on: May 06, 2014, 03:14:55 pm »
I have a 660 on the bench right now. It's my uncle's saw. He has complained about it before, says it has no grunt and cuts like crap. Looking it over it definitely needs the chain sharpened, but it's not terrible. P/c are in good shape. The muffler is really clogged up though, IMO. I trimmed the carb limiters and am going to give it a muffler mod. Just wondering what others have done, particularly with the baffle inside?  Did you drill or cut it out some more?  I'm thinking of putting a couple large holes in the front of the baffle plate where there are currently none, then a larger second exhaust port. Any input is appreciated.

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Offline Cut4fun .

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Re: 660 muffler mod
« Reply #1 on: May 06, 2014, 03:53:07 pm »
Remove the cage preferred method.  Drill cage out with bigger holes 2nd.

Also add a DP Dual Port muffler cover on the front. Then adjust the carb.

Aftermarket ones are a 1/3 of the cost of oem DP cover. 

10% off using this seller too.  http://www.hlsproparts.com/ProductDetails.asp?ProductCode=H90064&Click=2139&utm_source=googlebase&utm_medium=shoppingengine&gclid=CIq9yqmJmL4CFcU-MgodczUAOA   Hyway Stihl 064, 066, MS650, MS660 dual port muffler front cover

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Offline JohnG28

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Re: 660 muffler mod
« Reply #2 on: May 06, 2014, 04:32:19 pm »
Thanks cut. Is the port on those dp covers big enough to make a decent gain with some tuning after?  The muffler will be the only thing done with this saw,  just want a little more out of it. I'll look it over when I get home later and see about the cage. I'm going to try to get as much of it out as I can if not all. Thanks.

Offline Cut4fun .

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Re: 660 muffler mod
« Reply #3 on: May 06, 2014, 06:51:54 pm »
I tested a stock dp cover and a little more opened dp muffler cover without seeing any gains.  Oh I did have the side exhaust outlet already opened as big as the deflector instead of the  little hole they put out now days on the stock 660. So that could have made the difference in that cover test.
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Offline JohnG28

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Re: 660 muffler mod
« Reply #4 on: May 06, 2014, 06:59:14 pm »
Gotcha. Yeah the one that's there is about the size of a pencil eraser. It definitely doesn't let much out and was why I wanted to do a mod in the first place. I'll get that opened up while I wait on the dp to come in and see what I get from each.

Offline 660magnum

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Re: 660 muffler mod
« Reply #5 on: May 06, 2014, 08:22:18 pm »
I tested a stock dp cover and a little more opened dp muffler cover without seeing any gains.  Oh I did have the side exhaust outlet already opened as big as the deflector instead of the  little hole they put out now days on the stock 660. So that could have made the difference in that cover test.
Yes and that muffler works good too.
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Offline JohnG28

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Re: 660 muffler mod
« Reply #6 on: May 07, 2014, 06:06:09 pm »
I got a good chunk of the cage out, has a nice straight shot out into the can now. Was a pita to grind out so I didn't get it all, but still a good improvement. Could only get the factory hole opened up to size of a dime or so, but it's better. Gonna order a dp up later.

Offline JohnG28

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Re: 660 muffler mod
« Reply #7 on: August 24, 2014, 09:54:39 am »
Update: Had this saw sitting around my place for 6 weeks or so, he hadn't needed it for anything so wasn't in a rush. I had it dialed in pretty well with the dp cover but only had some smaller logs to try it in so wasn't sure how it would work stumping. Well he used it earlier this week. Said it sounded awesome to start! Which I agree with completely. But performance was up too, lot stronger one the stumps he used it on, said it laid right in and off to the races throwing chips! He killed the chain in the dirt so was cut short (for some reason he rarely files a chain >:( ) before finishing the stump,  but said he's very happy. Can't beat a $20 gain like that! And I'm pretty sure I'll be the owner of that saw some day, hopefully sooner than later. Thanks for the info guys.  ;D

 

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