MS660 Muffler Mod

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Ron660

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I'm new to the site and I'm sure this has been answered before. I have a MS660 and wanted to add or modify the factory muffler to get better performance. What's my best bet? I've seen a few comments about installing a dual port muffler or modifying my factory model. Also, would I have to adjust my carb if a dual port muffler is installed? Thanks, Ronnie
 
Easiest way is to slap on the dual port. Carb adjustment will have to be done, yes. But in an ideal world, you should be adjusting your carb almost every time you use the saw. Environmental conditions are never the same, day to day. High performance engines that pull every last bit of power out of combustion, need to be perfectly tuned.

See it like a dragster vs. a daily driver. The daily driver doesn't need a tune but once every couple years (pre-computer days), as it's tuned for general use and makes enough power to get the job done. A dragster is tuned every time it's used, for specific environments, etc. - trying to get every ounce of power you can. I view small 2-strokes the same way. I try to have my saws running 100% perfect every time I use them. It only takes but a couple seconds to tune it - less than a minute really.
 

“but don't go forward with the hole.What's this mean?

I will take a crack at this since I just did my 460 muffler mod. The dual port muffler has two holes obviously: One of the front cover and one on the side of the muffler body. The hole on the side of the muffler has a deflector shield over it to keep hot gas from hitting plastics and such. I think he means (it's what I did) to enlarge the side hole, only under the deflector but not so large that the hole is "moved forward" or no longer under the deflector.

Make sense?
-n
 
I will take a crack at this since I just did my 460 muffler mod. The dual port muffler has two holes obviously: One of the front cover and one on the side of the muffler body. The hole on the side of the muffler has a deflector shield over it to keep hot gas from hitting plastics and such. I think he means (it's what I did) to enlarge the side hole, only under the deflector but not so large that the hole is "moved forward" or no longer under the deflector.

Make sense?
-n

I see. I wasn't able to open the hole large enough on mine and still be under the deflector. Si I just cut the oem one off and made a larger one.
 
CDN dual port cover is the easiest way to go on the 066/660 and the 046/460/044/440. Bolt on the new cover and re-tune the carb, and instant power gains and a cooler running saw.

If you look at what Randy (Mastermind) does to these saws, they only widen the front slot on the DP cover. Works great.
 
Open the area under the deflector and get a dual port front and retune. It will make a noticeable difference in it. You can put a deflector on the left side if you want to instead of a dual port front.
 
Oh yeah the aftermarket dual ports fit pretty good and it seems depending on your area the OEM may be on back order for months. I know a few members have not had luck getting one.
 
I bought the one on ebay for $22 shipped. it seems plenty solid / strudy. Been working fine. stihl one is like 80ish?

Made by hyway so just google it.
 
Weedeaterman sells them also. I paid almost $70 2-3 years ago.
 
Thanks for all the responses. My local Stihl dealer ordered me the dual port front plate (item # 11221400800).
 
I bought the one on ebay for $22 shipped. it seems plenty solid / strudy. Been working fine. stihl one is like 80ish?

Made by hyway so just google it.

Just bought one from HL tonight, cant beat it for the price. What little I have heard on the a/m cover has been good.
 
HL is selling just the duel port cover for $18 on ebay. Will that bolt up to a stock 660 muffler?
 
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