Chain Speed and Movement at Idle on Stihl 250

[Vernon Tull]

In my limited, non-professional, "homeowner" chainsaw experience, the saws I've had generally have all been set up where the chain comes to a stop at idle speed, and the engine would idle fine with the chain not moving until I applied the throttle.

I have a fairly new MS250 Stihl that was just as described above until this week. Today I noticed that it seemed to idle fine, but the chain kept moving around the bar at a fairly good speed. If I touched the bar to a log to get the chain to quit spinning (still not applying any throttle speed), it would stall out and quit.

What has changed about the saw? Thanks.

 

[Lawn Masters]

Could there be something lodged in between the drum and clutch? if its fairly new, I cant imagine the spring(s) would be stretched out already, nor can I imagine it being an air leak though that is possible, perhaps the carb got leaned out a little on the low end somehow. I really cant tell you for sure.

 

[HELSEL]

It sounds to me like a clutch spring broke.You hardly ever get somthing lodged between the clutch and drum.Good luck let us know what it was.

Rick

 

[DanManofStihl]

I would try to adjust the carb and if that didn't work you would need new clutch springs. I had to replace them on my 066 mag not very fun to put them on or take them off.

 

[WRW]

Check the clutch bearing. Will the chain move on the bar with the engine not running?

 

[smcowboy1974]

I would say it's the clutch. If you touch it to a log and it stops the engine that means the clutch is still in mesh with the drum. If it wasn't the engine would continue to run. Take off the clutch drum, and see if you can find any problems. Good luck!

 

[Lawn Masters]

Probably the spring(s) are broken or stretched extremely far. at idle, these engines dont develop a lot of torque, at least not enough to keep the chain cutting while the engine is idling.

 

[tony marks]

could itbe a filter is not clean.if it was the air filter ,it seems to me it would make the air in less . this should slow the idle dn ,i think. but mabe this compensating carb is over compensating. if this sounds to simple ,its because ,not being a mechanic,ive learned to look for simple explanations. also is there a chance the carb adjust screws have vibrated in a bit. yours may have caps and i wouldnt think so ,but a simple adjustment mite straiten it out.in any case something changed . u dont know what . but experience has taught me to catch this stuff early ,or she ll change more when u are in the middle of a job or something.
input from a regular user of all sort of gas engines ,not a mechanic. but dn time is money so i catch this stuff early if i can.
u seem to be doing that ,so good luck.

 

[JamesTX]

How fairly new is it? For "limited, non-professional, homeowner" use, the warranty is one year. If it's not that old, I'd take it back to where you bought it and let them worry about it.

 

[Vernon Tull]

Some of you asked me to write an update when I got the problem solved with this MS250. I tried adjusting the carb screws as the manual instructs with little to no success in getting the idle speed/chain speed right. I took it to the Stihl shop here in town, and as it turns out, OldSawAddict was right in his diagnosis. I had loaned the saw to a neighbor the week before who had done some cleaning up around two fishing ponds. The Stihl technician told me yesterday that he found a big wad of fishing line wrapped up inside the clutch drum that was causing the problem. It's a wonder the saw was working at all. My neighbor has years of chainsaw experience, so I guess this was a simple accident rather than negligence. Thanks, gentlemen, for your suggestions.

 

[buckwheat]

mmm....chainsaws and fishing. That presents some interesting possibilities...

 

[turnkey4099]

Some of you asked me to write an update when I got the problem solved with this MS250. I tried adjusting the carb screws as the manual instructs with little to no success in getting the idle speed/chain speed right. I took it to the Stihl shop here in town, and as it turns out, OldSawAddict was right in his diagnosis. I had loaned the saw to a neighbor the week before who had done some cleaning up around two fishing ponds. The Stihl technician told me yesterday that he found a big wad of fishing line wrapped up inside the clutch drum that was causing the problem. It's a wonder the saw was working at all. My neighbor has years of chainsaw experience, so I guess this was a simple accident rather than negligence. Thanks, gentlemen, for your suggestions.

Another fine example of why not to loan tools. Getting the line wrapped up could happen to anyone but not to say anything about a problem when returning the saw is bs.

Harry K

 

[Vernon Tull]

I agree completely Harry K. !

 

[njforestfire]

The neighbor should have at least gone over the saw prior to returning it to you. He might of caught this problem and fixed it for you. So much for common curtisy.