Sprocket will not turn on Stihl MS 180 chainsaw.

Sparkplug ,If not. Try saw on half Choke, if works check filter in tank.

remove spark plug.
block ther piston with a piston stop.
remove clutch drum exposing the clutch
it has to be turned clockwise to remove it. 19m socket

Most likely cause is a dirty or out of tune carburettor. If there is a high speed adjustment, try turning that our a bit.

I assume you have the correct chain for the bar and that the sprocket on the end of the chain bar goes around. Check the bar for any defects like pinches where the bar has been caught. Check the chain drive cogs for any burs on the edges - often happens if the chain has been run too slack and then come off!

Check the chain drive teeth thickness which should be the same as the chain bar can accept. Check also you have the right pitch chain for the drive teeth on the clutch sprocket. Assuming the chain brake is not on then you should be able to move the chain around the bar when all the slack has been taken out. If the chain and bar checks are all ok then there is a problem with the clutch. With the chain brake off the clutch with the chain drive sprocket on should spin reasonably freely. If not then you need to remove the 'E' shaped circlip in the centre of the clutch drum , remove the washer behind it and slide off the clutch drum. Then remove the roller bearing and be prepared to replace it if it will not run freely. Clean out all the muck in the clutch housing and check for anything obviously broken. If all appears ok then put a few drops of 2 stroke oil on the roller bearing and replace it on the shaft. Clean the clutch drum and replace it on the shaft. Then the washer and 'E' clip and re-fit the bar and chain. Re-fit the cover and tension the chain and try again. If that does not do it then there has to be a problem with the chain bar.

Remove the side casing. (bar side)
Take off bar and chain.
Remove E-clip holding the clutch drum on.
Remove clutch drum and needle cage bearing.
This should expose the clutch.
Remove spark plug.
Use a piston stop to stop the piston rising, Sometimes a knotted piece of pull cord fed into the cylinder is just as good.
Turn the clutch clockwise with a socket to unscrew.

To put clutch back on turn anticlockwise till piston cycles back and hits the piston stop again and tighten. Replace spark plug and clutch drum, bearing, bar and chain and side casing.

Are you asking something, or telling someone to replace a pullcord on a chainsaw?

check and see if the muffler is stoped up

check the spark arrester screen in the muffler. if they stop up it will run like it has
no power and will stall

Chain cover removal for all model 180s is illustrated under "Mounting the Bar and Chain"
Stihl Product Instruction Manuals
http://www.stihlusa.com/stihl_ownersmanuals/MS170_180_Manual.pdf
It has an inboard clutch, this may help.

R² Drive Link Inboard Clutch by Drivelink.blogspot.com
http://www.youtube.com/watch?v=YUbSIHMSSP8
The C-clips tend to fly when being removed. Please wear eye protection and exercise care. HTH
Lou

I have a stihl ms 180 that leaks bar oil all the time