Upgrade MS 660

[Cruiser_79]

I want to upgrade my 660. With a 36'' bar I want it to have a little more power. Will it make a difference when I just add a dual port muffler and put a larger jet in the carburettor? I think that's the difference between a regular 660 and a 660 magnum isn't it? On the site of saegenspezi.de I can order a dual port muffler and new cilinders etc, but I can't find bigger jets for the carburettor. Better to go to the Stihl dealer? Is a lot of adjustment needed when adding a dual port muffler and a bigger jet? 

[teakwood]

I just did the double muffler and richend the carb settings on my 066. it ads 10-15% power and the saw works cooler which is better for engine life. of course more power means more fuel consumption.

[Dave Shepard]

I don't think the jets are replaceable. Just adjust as needed.

[Cruiser_79]

I purchased a dual port muffler, so I will replace it this weekend hopefully. Any tips for adjusting the carb settings? Did it once with my 341 but that's at least 8 years ago so I don't remember it that good  : Today I'll go to the dealer for some motomix, I hope they have a tacho meter cause my old one dissapeared apparently. 
Will the 660 run with the dual port muffler to warm the engine up? Adjusting should be at working temperature but than it needs to run a little bit.. 

[teakwood]

If i remember correctly you have to richen the H screw. at full throttle you need to hear the "4stroke" sound

[Mad Professor]

I sort of do what Madsens calls for to set Hi/Lo, I don't have a tach.  Go back and forth a few times between Hi/Lo and idle.

http://www.madsens1.com/saw_carb_tune.htm

When I have saw set to just blubber/4-stroke at WOT I then fine tune in a cut.  Have chain sharp and blubbler should just clean up when you are in full cut.  You may want to go back and forth on this too fine tuning the Hi.

After a tank or so check the spark plug and inside of muffler for lean/rich.  I never hurt a saw doing it this way.

Your 660 carb may have limiter caps on Hi/Lo to deal with if you can't move screws far enough to adjust things.

[Tropical Sawyer]

Richen the high screw about a 1/4 turn before you first start it up. Then adjust from there following the Madsens guide as the professor mentioned, and you shouldn't have any problems.

[Cruiser_79]

I placed the new exhaust and tuned the carb. It start's, run and idles good. I first adjusted the idle screw, than the low speed screw in between too rich and too lean. When I give full throttle and richen the H screw till it 'blubbers' the saw runs good and accelerate quite fast. But I checked the RPM's and it isn't getting above 11000 rpm's. Did I richen the L screw too much? For me it isn't a problem, it runs good and reacts like I want it. And better too rich than too lean in my opininion...