Noob tuning on a Stihl

[JeffHK454]

Got me a brand new MS 440 with about 5 minutes of run time on it , I think I need some tuning pointers. I won it at a local auction and ran it just to make sure that it was in working order. I was the first person to put oil or gas in it. I bought a DP front cover for it but was not impressed with it's opening size. I took the stock muff cover and tig welded in a 7/8 dia SS tube, 2" long with a 90 degree bend, lucky for me I am a much better metal fabricator than I am carb tuner .


I'm assuming that "H" is high speed rich/lean?
....................... "L" is low speed rich/lean?
........................"LA" is idle

With the pipe mod that I've done will the "H/L" factory Stihl limiting caps keep me from achieving a proper state of tune ?

As you can tell there will be no tach involved in my tune job, but should it be tuned with no chain WOT or with the 25" chain on ?

Also seeing as this will be a " by ear" job what sounds should I listen for in it's acceleration and WOT?

Sorry about asking the most over asked question of all time !

I was not sure how the pipe configuration affected the tune job ?

Thanks for the help, Jeff

 

[fishhuntcutwood]

Have you done a search on here yet for this? There is quite a bit of reading on the topic of tuning a saw.

You are correct about the H, L, and LA screws. As far as putting gas in it, that should have been done at the dealer before it left the front door, but perhaps not. After opening up the muffler like you described, you will certainly have to remove the limiter caps to richen the carb up enough to get it running properly. Stihl makes a special tool for it, which you can get from a dealer. It'll cost you about $5. P/N is 5910 890 4500. Madsen's has a decent dutorial, complete with audio clips on how a saw should sound during each step.

Jeff

 

[Lakeside53]

It's likely that you'll need to remove the limiter caps from the carb to perform any serious tuning on the high end, so the first thing you need to do is buy the tool... or get it removed by a stihl dealer. Using a screw or pretty much anything else will result in a jambed cap that will need to be dug out the hard way... Buy a new cap when you replace it (50c).

Tuning:

Rather than type in a long winded explanation, here's an excellent link:

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

 

[JeffHK454]

Thanks guys for the help, I also forgot to mention that I will be using 40-1 Stihl 2 cyl. and premium gas.

I did try the search feature but I might have been to specific on my request.
I guess most any tuning info will apply to my saw?

Jeff

 

[Lakeside53]

"almost any", but don't exceed the max RPM if you want good saw life. Other will disagree, but If I was you I'd just set the top end with a tach to about 13,500 (bar and chain on) and forget what it "sounds" like. Borrow a tach, and try it without removing your limiter caps - you may have enough adjustment room at "full rich" (counter clockwise of the H screw).

 

[fishhuntcutwood]

"almost any", but don't exceed the max RPM if you want good saw life. Other will disagree, but If I was you I'd just set the top end with a tach to about 13,500 (bar and chain on) and forget what it "sounds" like.

Agreed. Others will say differently, but they're the modded saw crowd, and that's fine. I've got opened muffler on each of my saws, and that's the extent of it. They probably could run faster, but I don't like getting above 13,800 or so tops. Maybe it's just a mind thing, but I think my saws run fine enough for my needs, which don't include racing or timed cuts.

Jeff