Stihl 039 (1994) MS 660 (2008) looking for simple mods to get more power.

[ShadeTreeWelder]

I am always short of time due to too many projects, farm, work,
kids, hunting (one has to have priorties and principles), etc...

I would like to get more power out of my 039 and 660 but I am just
looking for bolt on modifications, carbs, mufflers, air filters etc... I
am not going to get any porting done, or custom work.

I am sure the answers are here in the forum somewhere. Yes I
have spent the last hour searching and reading and I am more
confused now than when I started.

What are your suggestions?

 

[mtngun]

muff mod on the 066

 

[ShadeTreeWelder]

muff mod on the 066

Does someone sell Modified mufflers I can bolt on?

If not, how does one do to, I am a virgin be gentle.

 

[Mad Professor]

Does someone sell Modified mufflers I can bolt on?

If not, how does one do to, I am a virgin be gentle.

OEM dual port cover for 066

 

[mtngun]

Yes.

Stihl will sell you the dual port cover, all it takes is money and a high tolerance for noise.

I think someone sells a modded muffler on the bay.

I'd suggest opening up the internal baffle. Just drill bigger holes and/or more holes.

Personally, rather than buying something, I just open up the existing single port with a carbide burr. There's plenty of room to enlarge the single port.

 

[ShadeTreeWelder]

Yes.

Stihl will sell you the dual port cover, all it takes is money and a high tolerance for noise.

WHAT?...

Lol, still kinda funny online, too many years in loud Destroyer
engine rooms. Already half deaf, and don't like most of what
I hear nowadays anyway...

Is the piston picture you showed just for measuing the exhaust
port size? The exit port on the muffler should be 80% of that???

 

[mtngun]

Is the piston picture you showed just for measuing the exhaust
port size? The exit port on the muffler should be 80% of that???

A quick and dirty rule of thumb is that the total area of the exit port(s) should be 85% of the area of the exhaust port, as measured at the cylinder wall, not at the flange.

Not sure what you meant by "piston picture ?"

 

[Anthony_Va.]

Like has been already said. Muffler modding both saws will wake them up. You can either get the DP cover for the 066, or just open up the stock hole. I think theres enough room under the flange to make a big enough hole. Just open the 660 up to around 3/4"-1" and the 390 up to maybe 5/8"-3/4". Should be plenty.

Not much more you can do besides porting. You can take your jug off and just clean up the ports lower transfers and gain alot, without any real porting.

 

[betterbuilt]

I'm pretty sure the OP is planning on milling with his saw and a dual port might not be the best route. The exhaust bouncing of the log is something to think about. Starting a fire is another.

 

[z71mike]

Wojo sells them on eBay. Pricey, but if you have money to blow, his stuff kicks a$$....

LINK

 

[mtngun]

I'm pretty sure the OP is planning on milling with his saw and a dual port might not be the best route. The exhaust bouncing of the log is something to think about. Starting a fire is another.

+1

I ran a dual port for a while. Milling on a hot July day, it would make my gloves smolder. Bucking, it would set the bark on fire.

Modded single port makes so much more sense to me, but some people really like to throw money at those dual ports.

 

[betterbuilt]

+1

I ran a dual port for a while. Milling on a hot July day, it would make my gloves smolder. Bucking, it would set the bark on fire.

Modded single port makes so much more sense to me, but some people really like to throw money at those dual ports.

I caught a punky log on fire and couldn't have been farther from water. I ended up using dirt to put the fire out. I'm pretty sure the heat is what made my chain break plastic get hard and brittle. It eventually broke and they run about $50ish to replace.

 

[a1stump]

If you can give up some inches of bar, put a 20'' or 25'' bar on the 660 and there will be no need for power mods, that mother will rip! If you are cutting big wood, then obviously you can't down grade the bar. I have a 066 with a 20'' and it has stupid power. I also have a 660 with a 28'' and it still could handle more, but I don't put my 3 foot bar on unless I need it.

 

[z71mike]

If you can give up some inches of bar, put a 20'' or 25'' bar on the 660 and there will be no need for power mods, that mother will rip! If you are cutting big wood, then obviously you can't down grade the bar. I have a 066 with a 20'' and it has stupid power. I also have a 660 with a 28'' and it still could handle more, but I don't put my 3 foot bar on unless I need it.

Dude. Thread is 3 yrs old.

 

[a1stump]

It was at the top of related forums, just get my "post" on lol

 

[a1stump]

People go on old forums all the time when they are looking for the same answers to similar questions, I encourage others to answer as many questions on these forums as possible to add archives of useful information to the public. If only people would answer questions that I have!!!!!!

 

[MustangMike]

For the 660, buy an AM dp muff cover, remove the baffle in the muffler, and put an HD-2 air filter on it. It will make a noticeable difference (U will be happy). U will also have to remove the carb limiters and make the tune a slight bit richer. To remove the limiters (plastic around the screw) start a drywall screw in them, line up the tab w/the slot, and pull them out. Not a big deal.

Good Luck, it will be worth UR trouble.