Stihl MS400CM break in?

[KWood255]

This past spring I bought a new MS400CM, which I've yet to burn a 2nd tank of fuel in. I always seem to grab my 261 instead.

With the very limited use I've had, the 400 seemed to stutter a bit when working through a big spruce, almost like it was bouncing off a rev limiter. I heard a rumour that the "CM" saws have a factory break-in mode, which takes several tanks of fuel to eventually clear. Accurate? If so, are there increased performance gains once out of the break in mode?

[sawguy21]

What is recommended in the manual? It may need a couple more tanks of gas to loosen up.

[lxskllr]

That doesn't sound right to me. I don't believe there's any computerized break in routine. As Sawguy said, it'll break in over several tanks of fuel. For your immediate problem, it may just be an issue of lack of use. The computer maybe hasn't dialed in the settings yet. Also, I'd switch the shutter to the cold weather position if it isn't there. You may be getting a bit of carb icing.

[hedgerow]

It took close to five gallons of mix ran threw my 261 CM before it became the saw I thought it should be. Then I was impressed with the saw. Even when I bought my non CM 461 it took five gallons of mix threw it before it really ran like it should. Both have been great saws.

[chep]

Run it more!

[421Altered]

 drag racing engines are first run and broken in using conventional oil.  Then after one or two runs down the track the rings are seated and then the oil is changed to synthetic.  That's what myself and all my racing friends do.  The rings seat quicker that way.  Should also hold true for chainsaws.

[421Altered]

I should add, I bought a new cm261, I used conventional mix oil for the first gallon of gas I put through it.   After that, I have only run synthetic.  I, like many other's on here am very pleased with my 261!

[ehp]

Todays engine mix oil is fair better than 20 years ago , I run klotz synthetic in all my saws from the first time the saw is every started , My very first 462 arctic was just torn down cause a buddy needed a saw so I told him this saw has a quite high number of hours on it and he said it was like brandnew inside with no carbon , As far as how to run the 400 , run it like you stole it and make the saw cut , if your hitting the rev limiter either your chain is dull or your not making it bite into the wood hard enough , if your cutting real frozen wood then make your chain cut cause ,025 on the rackers does not work

[ehp]

you will find pretty much like any of the 400, 462 or 500 from stihl they take time before they are up to full power , Run good oil and good high test gas and saw will last you a long time , If you want abit more power put a bark box on it , its the outter muffler piece that allows the motor to breath better and get rid of some of the cylinder heat  but it is louder but I run them on all my saws I fall timber with , they are not cheap but made of good metal so I have not put a single mark on any of them