A couple muffler modded Stihls.

[SawJunkie]

Finally got to cut some today after work with my 390 that I did a muff mod on. It's running right around 14,200 and the improvement over stock is pretty substantial I think. It seems to be cutting really well where it's at so think I'll leave it. Also took the 440 along to finish noodling up some big rounds so I could move them. It has the factory DP muffler cover. It's just getting broke in good and I probably have somewhere around 10 tanks of fuel through her. Probably a few more than that. Anyway, I put the tach on just to see what she was turning. I was pretty surprised when I saw 16,000 reading on the tach!! I am guessing she loosened up a bit since I last adjusted the carb. I am thinking I better turn the saw down to about 14,500 or so to be safe. Cut like crazy, but I don't want to seize it.

 

[splitpost]

Finally got to cut some today after work with my 390 that I did a muff mod on. It's running right around 14,200 and the improvement over stock is pretty substantial I think. It seems to be cutting really well where it's at so think I'll leave it. Also took the 440 along to finish noodling up some big rounds so I could move them. It has the factory DP muffler cover. It's just getting broke in good and I probably have somewhere around 10 tanks of fuel through her. Probably a few more than that. Anyway, I put the tach on just to see what she was turning. I was pretty surprised when I saw 16,000 reading on the tach!! I am guessing she loosened up a bit since I last adjusted the carb. I am thinking I better turn the saw down to about 14,500 or so to be safe. Cut like crazy, but I don't want to seize it.

16,000 would have been way to lean ,turn it down to where its 4stroking good and go with that

 

[Evan]

Yeah good burble at wot and put the tack away. Also check in in wood and Baker minor adjustments

 

[Anthony_Va.]

ea, my 660 is right when set at 13,900 RPM with the DP and the stock outlet opened up to around 3/4". Stock is 13K.

I would think 14,5K would be max and I would keep an eye on the tune. Mine is cleaning up completely in the cut and burbling a bit at WOT.

 

[SawJunkie]

ea, my 660 is right when set at 13,900 RPM with the DP and the stock outlet opened up to around 3/4". Stock is 13K.

I would think 14,5K would be max and I would keep an eye on the tune. Mine is cleaning up completely in the cut and burbling a bit at WOT.

I'll turn it down next week. I've been to busy working and the weather is miserable here. I pulled the muffler off and the piston and cylinder were fine. I was a little paranoid I guess.

 

[DG2244]

16K ! That's screaming. Good for a weekend race saw but not going to last you long as a work saw. Manual says 13,500 +/- but tuning
to a mild 4 stroke is a proven method.

 

[stihl 440]

WOW 16K!....and i thaught my 440 doing 14,100rpm was pushing it..lol..but my plug is still light brown...