MS210 dies at low idle

[LeeB]

The wife's ms210 seams to be idling really low and dies at throp of a hat. Hard to keep it running. I looked for an idle screw but couldn't find it. I pulled the plug and cleaned it. It was a little fouled but not bad. That helped for about 15 minutes. Any ideas ? This is a new saw with less than 20 hrs on it. ran great till today.

[dancan]

check with your dealer , a good one will want it back to check it over .

[sawguy21]

Try turning the idle speed screw in until the chain starts to move then back out a tich. I believe the mixture settings are fixed on that model.

[stihl #1]

The 210 has H and L screws. Since the plug was a little fouled check the spark arrester screen to see if it is plugged. If not the carb needs tuned. Best practice today is to tune it with a tach. If your dealer won't help you out put up another post and I will walk you through it if you are not sure how to tune it.

[thecfarm]

stihl#1,welcome to the forum.Must be a stihl man.   

[LeeB]

I haven't tried the dealer yet, which is undoutably my best bet since it's a new saw. I don't get out much and the dealer is 30 minutes away. Thanks everyone for the replies. I'll check for some of this stuff tommorow. If it isn't an easy fix to the dealer I go.

[LeeB]

Apparently I don't even know what saw I have. It's a 180 and not a 210. Still used all the same advice and she's doing just fine now. Upped the low idle a little and cleaned the flash screen. Cleaned the plug again and the air filter. Running like a champ now. The saw came with this neat thing called an owners manual. After reading some, best I can figure is I haven't beeen running wide open during some of the cuts and this caused it to load up everything with unburnt fuel and oil. Thanks for all the help everyone.

[stihl #1]

Thanks for the welcome! Yes I am a Stihl man. I have about 40 of them in the collection. Too many saws and not enough time...
The MS 180 does not have mixture screws, it has a fixed jet carb. This saw is tuned lean from the factory, so anything that makes it leaner is trouble. The carb does not have an accelerator pump or part load enrichment jet, so running it at half throttle or just blipping the throttle is bad for it. Always cut with it at WOT (wide open throttle) so you get max vaporization cooling from the fuel to the piston. About the only thing that will make it run rich is a clogged up filter. Make sure the fuel is fresh, meaning not over 1 month old, and try to stay away from alcohol fuel if at all possible.

[thecfarm]

Seems like I heard that a chainsaw has 2 speeds,idle and wide open.They small motors need to be run hard to run right.

[logwalker]

One thing that a lot of people overlook is the effect of oil/fuel ration on fuel mixture ratio. Simply stated the richer the oil mix the leaner the fuel mix. In this case the addition of extra oil in the mix could seize the piston. Not what you would expect, eh? Joe

[MartyParsons]

We have been experiencing rich conditions on some of the Stihl chain saws. They are putting grafite ( spelling) on something like it on the fuel inlet needle. We have cleaned a few of these. Not a big deal just remove the carb and clean the inlet needle ( rubber tiped) ( spray a little carb cleaner on a rag and wipe lightly) and things are back to normal. The home owner saws seem to be the worst for this. Any one else see this?
Marty

[joe_indi]

They are putting grafite ( spelling) on something like it on the fuel inlet needle. We have cleaned a few of these.

The graphite has always been there on new inlet needles.
A brand new saw may not start because the needle sticks initially.To get it working, the easier thing to do is to blow into the air compensator.This causes the diaphragm to go down and depress the metering lever, which causes the needle to lift up.Once it lifts up the fuel flowing in will wash off the graphite.

We have been experiencing rich conditions on some of the Stihl chain saws

Marty you are correct about this.I've had quite a few new saws that came in since 2006 with the complaint of flooding.Even a needle replacement wouldn't help.The fault was in the needle seat.
I found the perfect cure for this! Use a graphite pencil for lapping the needle seat.It works!But be careful, don't apply too much pressure or the graphite will snap off.If this happens remove the strainer at the bottom and use a tooth pick to push the broken bit out.

[SawTroll]

  And the closest dumpster is how far away.......

[SawTroll]

Seems like I heard that a chainsaw has 2 speeds,idle and wide open.They small motors need to be run hard to run right.

That is true - the throttle should be used as an on/off switch, no inbetween, or .......

[logwalker]

I have used all my saws (+20) for the last 36 years at all degrees of throttle opening and Have never had any sort of problem that I would attribute to PTS (partial throttle syndrome). Can someone that is propagating this Fact/Myth please tell me what I should look for. Joe

[thecfarm]

I have no data to back me up about idle and wide open speed,just what I heard the GOL will tell you to do up here in my neck of the woods.

[Timburr]

As you know, a chainsaw carb. is setup with low and high mixture screws.   The idling mixture metering jet is located adjacent to the throttle butterfly.   As the throttle is opened, there is less vacuum to pull  the idling fuel through.   More throttle and idling mixture becomes redundant.   
The high mix is metered into the venturi - a narrowing in the carb body.   The more airflow though the carb (max. power) and the more efficient the high mixture metering becomes.   When the airflow is low at idle, little fuel is delivered through the high jet.   
During a mid rpm scenario, neither the low or high mixtures are at their optimum and a "vague" mixture occurs, usually weakened.  Although there's adequate mixture to run, a longer period of middle revs will starve the motor of enough lube......

So yes, it is all or nowt (nothing) imho!

In reality, running a saw at medium revs  only occurs for the short term.   As soon as power is needed, we inadvertently rev up!

Are you any the wiser, or have I tasked to confuse you even further. 

[logwalker]

Timburr, Are you assuming that the main jet efficiency is not adequate at partial opening or can you support that as fact? Have you ever seen an owner's manual that directed you not to use a partial opening? I am not saying that you are wrong, just would like to know if you have access to good information that I may have missed. The dynamics of air flowing through a venturi and metering fuel into that air stream is very complicated. I don't hear the engine running lean at partial throttle. Seems like I would. Even if it was my guess is that the amount heat generated at partial openings is not enough to cause problems. I guess it might be time to do the ol' spark plug mixture reading. Does anyone want to join me so we can pool our results? Later, Joe

[logwalker]

One more thought for you jugheads out there. The low jet supplies the mix at idle and the high jet under power. If Timburr and others are right then what supplies the mix when you dump the throttle wide open from idle. According to the above explanations then neither circuit is working as the venturi is wide open but there is almost no air flow. Hmmm

[Timburr]

.....If Timburr and others are right then what supplies the mix when you dump the throttle wide open from idle. According to the above explanations then neither circuit is working as the venturi is wide open but there is almost no air flow.....

Logwalker, good point.  To be able to accelerate, an engine needs a richer air/fuel mixture.   When I was learning from the British equivalent to your GOL course, we were taught to enrich the idling mix a tad (¹/₈ to ¹/₄ extra turn out) from max. idling rpm.   On the top end, the engine was tuned to rpms or just untill/before it started to "4 stroke", giving a richer mix and optimum power.   By setting the high and low slightly rich, it better compensates for the transition between the two.  Not an ideal situation, but IMO the best there is with this type of carb.   A vehicle carb has a better mid-range, because of accelerator pumps and or variable jets.
Just imagine setting both screws slightly weak (heaven forbid), you'll almost certainly have acceleration hesitation on any saw!

I'm unable to give you hardened literature to substantiate the above.   In fact, I've not opened a chainsaw manual for years.      The knowledge is an accumulation of two decades worth as a mechanic.

[joe_indi]

There are progression jets(two or at least one) in the carb barrel that supply fuel during partial throttle.
The idle jet is in front of the throttle shutter(butterfly).The other two are located behind the throttle shutter
These jets get the fuel through the low speed circuit.