ms440 dual port

[Vman]

just got a stihl dual port cover.
anyone have an approximation on how much to richen it up? will i need to richen both the L & H? and will i need to remove the limiter caps to richen it enough? ....the muff cover is a Stihl dual port cover.

and yes....i did try to use the SEARCH tool but it does not seem to work at this time.

thanks

 

[046]

look on madsen's site for detailed tuning instructions...

 

[rbtree]

I'd suggest dremeling the stock port to as close the width of the deflector as you can, to about 9/16th i.d. and enlarging the new oblong port about 30%. Then it will be able to breathe as it should. If you do nothing, you'll have about the equivalent opening of the old stock single port, which was 9/16th or so....that new ported cover is just too small. I had to remove the limiter caps...try gently inserting a small wood screw into the cap, That should hold the cap well enough to turn it couterclockwise till you can gently lift it past the shaped end of the jet that's holding it.

 

[CaseyForrest]

How can you have the equivalent of the stock port while adding the dual port cover? You are adding another port, the stock port and the opening in the cover, essentially 2 ports.

 

[tek9tim]

I think he's talking about the old school, metal tag 044 exhaust port size, which was a lot bigger.

On several saws, I have opened up the stock port larger than rbtree was suggesting, with no ill effects. Sure, when you flip the saw clutch side up to make a cut your hand can get blasted with exhaust if you aren't holding on to the handlebar in just the right spot, but that'll happen anyhow.

 

[5555555]

Casey,

The original stock mufflers had a lot larger diameter exhaust hole than they've come with for the last few years. If you compare the two, the old version has about twice the area. If you add the dual port cover to a new muffler, I think he's saying that you'll be at about the same exhaust area as the older version.

Jim

 

[Lakeside53]

look on madsen's site for detailed tuning instructions...

While it's o.k. to tune by ear for the 4 stroking sound, it's important to check your high end with a tach. On some saws, if you open up the muffler you can easily exceed the max RPM allowed by the manf. You might choose to go higher, but it's important to know you've made that choice! On some of the semi-fixed jet carbs you run out of adjustment to the rich side and will need to also replace the fixed jet.

Also, for a stihl saw, tune it with the typical bar length you intend to use, and a correctly tensioned chain.

 

[Vman]

thanks for all the info..much appreciated! i will take it all in to account and play with it in a little while if the rain stops, than see if i can find a log to test it out on....all my wood is cut to length at the moment, but have some smaller lenghts laying around.