Unstick valve in chainsaw

Use cutting oil (ATF Fluid works well) and let it soak overnight, if that doesn't free it you need to remove and rebuild the engine. You can (after waiting for the oil to work) try a wooden dowel that will fit in the spark plug hole and then hit the dowel to try and free the sticking piston, use finis, tap with only moderate force repeated times.

First, stop your engine. Check to make sure that the chain brake isn't engaged. The chain brake can activate automatically by a sudden movement or impact. You can disengage the chain brake by pulling the chain brake hand guard back against the front handle and releasing slowly. If the chain brake is disengaged and the chain does not turn; turn off the saw, then check the drive links on the chain, the bar groove and the sprocket nose on the bar. A burr on the drive links will bind the chain in the bar. If the bar has been pinched, the chain will not pass freely through the groove. If a sliver of wood has gotten into the sprocket nose, it will not turn at all. Also, look at the drive sprocket on the saw itself to see if it has a groove worn into it. A drive sprocket with a groove worn into it will damage the chain.

Ok, so if the clutch is turning and everything with the engine is functioning properly, then it can only be the chain or the chainsaw sprocket. Have you replaced the chain just recently? I'm only asking because even though it may be the right length, there are chains that have different sized drive links. Very seldom do the sprockets wear, but I have seen alot of times where someone buys a new chain and the drive links are either too big to sit properly into the sprocket or they're too small...

Obviously your chain brake is off correct?....

Removal>

1. Remove the clutch drum/chain sprocket
2. Remove the air filter
3. Take out the shutter.
4. Pull boot off the spark plug.
5. Unscrew the spark plug.
6. Close the decompression valve, if fitted.
7. Push the locking strip 0000 893 5903 into the cylinder. (Piston Stop)
8. Unscrew the clutch from the crankshaft clockwise (left-hand thread).

Installation>

1. Screw on the clutch and tighten down to 50 Nm (37 lb.ft).
2. Install the clutch drum / chain sprocket .
3. Remove locking strip from the cylinder.
4. Insert spark plug and tighten down to 25 Nm (18.5 lb.ft).
5. Fit boot on the spark plug.
6. Fit the shutter so that its lugs engage the recesses in the handle housing.
7. Install the air filter

Did you make sure the brake was off before re fitting the side cover, if not the band will be smaller that the drum and will jam the drum and stop it from turning.

there might be a manual break on it

The chain may have come off the sprocket.
There are 2 nuts about an inch apart down just past the bar which hold it in place.
Remove the 2 nuts, take off the cover which they hold in place and the bar and chain will loosen.
Check that the teeth on the inside of the chain are on the sprocket. Pull the chain tight against the sprocket and move it. Check that the sprocket turns. With the chain set in the sprocket replace the bar, chain and cover and try turning it again by hand. If it doesn't turn don't try to start the saw as you'll do damage.

If the chain was on properly and it still won't turn the clutch may be burned out. However the fact that you couldn't turn it by hand suggests that the chain was off the sprocket.

The sprocket should be fixed to the outer clutch drum. With the engine off, and the bar and chain off, hold the sprocket with channel lock pliers and turn the outer clutch drum by hand. If the sprocket does not turn, but the drum does, then the clutch must be replaced. (Left hand threads) To keep the engine from turning while trying to remove the clutch internals, stuff starter cord into the upper cylinder head area so that the piston cannot rise above the top of the exhaust port. If you have a saw service shop near you, you might farm out the clutch replacement. It usually requires a special tool to turn the clutch internals. Good luck!

the threads are left hand.i my self use a small butterfly air rachet to remove the nut. it spins fast enough to remove the nut.

mso 9]> Normal 0 false false false MicrosoftInternetExplorer4 mso 9]> mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.25in 1.0in 1.25in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} --> mso 10]> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} Hi tchild,
my name is Dennis Gladx and I can assist you with the problem of getting the sprocket off of the crankshaft of your chainsaw.

To remove the centrifugal clutch and sprocket you unscrew it from the crankshaft and it has a left hand thread. Also a little trick to remove anything from a crankshaft that could turn while you want to unscrew the item, Remove the spark plug and insert some rope into the cylinder for the piston to squeeze against and you will jam the piston without damage.

Glad to be of assistance Please rate this solution because I can learn from your rating. Thank you