MS660 Exhaust Opening Observation

[Racerboy832]

I was bored last night and I had a Stock MS660 muffler in front of me and a metric caliper. I measure the exhaust opening where it attaches to the cylinder and it was approx 551mm (29mm X 19MM). They I measured the actual opening in the muffler where the exhaust Exits. and came up with 110MM. Well I've always used 85% of opening should be the exit size. Well that is 466mm Well I guess Stihl makes these 356mm Smaller for emmissions. No wonder they seemed so choked up. Just my observation.

 

[blsnelling]

You ought to see an old 066 muffler. You'd wonder how the new saws even run. The old muffler has a MUCH large opening.

 

[Racerboy832]

Can you find them used for a reasonable cost? I keep seeing some old 064 Exhaust pop up on ebay. I have a full machine shop and Fabrication shop below me. I was trying to think of something creative to do with my Exhaust.

 

[mtngun]

Just open up the side port. It's possible to make the opening several times larger while keeping the spark screen.

Some people add more holes to the inner cage or remove the cage entirely. I'm not sure if the older 066's even had the inner cage ?

 

[wi50]

My 660 has a dual port muffler, the original side port opened up to about a .750 square and a port added to the other side of the muffler a little larger yet, it runs like it should, or at least close to it anyway.

The exhaust duration is pretty long in some of the newer saws (660), that small stock port works decent with the long duration, but there's plenty of room for improvement

 

[Tzed250]

The large outlet muffler is still available.

Part number: 1122 140 0603


See this thread:

http://www.arboristsite.com/showthread.php?t=91351

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