20 inch bar on a MS390?

Depends on what powerhead the chain is strapped to. 24" bar on a 660 will make it cut slower.

You may be right but I thought the wood cleared out quicker and it had a benefit other than just running a bigger bar than the saw could handle, am thinking about getting a skip tooth for my 28 inch bar on the 045 to try it out, seems to pull it fine but was under the impression the skip tooth was better on a longer bar.

This is on target! 390 however just cut to the case out the shoot!

If we're talking possibility of dirt, semi-chisel may be better option, for keeping it sharp.

Nobody's yet mentioned gauge (thickness of drive links)- bar and chain must be nominally the same.

So as long as my 045 will pull it I am better off with the regular chain? Not trying to hyjack this thread just trying to add to the skip tooth vs regular chain.

Yes. How many cc's you got?

75cc I already have the bar on the saw and it does pull it with a regular chain but will I see a benefit from the skip tooth?

My current chain is 3/8, .50, 60

You should be golden with anything up to a 28 inch. 32 go full skip. Skip good for dirty wood less teeth to sharpen.

You also need to consider the space between the cutters for chips. A long bar in big wood will cut a lot of chips and have to carry them a long distance.

41 inch on a non skip 880 is like pouring water out the back of the saw. Bigger the saw the bigger the chutes is.

I would agree. I have a husky 50cc with a 20" bar. It is underpowered, but gets the job done. 24" sounds about right on a 60cc saw.

I have a 390 and a 20" its all i have ever run. It can pull all the bar through oak. Keep a sharp chain and it will be fine, it can get bogged up if you force it though but the 390 is a big saw !

Hear! Hear!

Agreed, except skip the full comp chain and go right to a skip tooth.

I've run a MS390 (stock) with Stihl Full Chisel (33RSC72) on a 20" bar. It pulls that with authority. If you wanted to go 24".... I doubt it would have trouble with that and if going full-skip seems too extreme there's always Stihl's half-skip full chisel....

I'm not a fan of big bars and don't use them but this is extremely good advice if using a bigger bar than what is recomended by manufacturer.

FWIW, I like the skip chain on the 24" bar & longer, cuts faster than full comp chain by nearly a full second in a timed cut on 30" red oak. 064 revs @ 12,500 with an 8 pin rim I get pretty decent chain speed, & plenty of power in the cut. I tend to run the shortest bar I can get away with for the reason Lee mentioned. As someone already mentioned, less teeth to sharpen on the skip chain. A C

You got it.

Yea thanks, hard won experience there, but lessons I'll never forget LOL. HAPPY NEW YEAR!!

Stihl recommends 16"-25" bar on a 390.

Just sayin'

Uhhhh,,,,, no!
http://www.stihlusa.com/chainsaws/MS391.html