Small Engines (Lawn Mowers, etc.): Stihl 028 AV chainsaw, piston damage, stihl 028

Question
Saw was acting as if it was starving for gas and would cut off.  Rebuilt carb., fired it up and was running good, when it shut itself off at full throttle.  Now cannot get it to start.  Seems to be "more than normal" resistance when pulling starter rope.  Checked cylinder for excess gas by removing spark plug and pulling rope.  No visible gas and starter rope pulls with "normal" resistance with spark plug removed. Cannot get it to start.  Seems to have good spark.  Any help would be appreciated.  Thought about pulling flywheel and checking it key is sheared but not sure of tapped hole sizes in flywheel.  My normal flywheel puller kits bolts are all to large for tapped holes

Answer
Hello Keith:

Remove the Cover that Houses the Starter Assembly. Use a Bolt the Same Diameter and Threads as the Spark Plug and About 3" Long. Thread the Bolt into the Spark Plug Hole Until it Engages the Piston. Slowly Tighten the Bolt Until you have Locked the Piston and it Does Not Move. This Holds the Crankshaft Still While Performing Repairs on the Flywheel or the Clutch and Sprocket. **BE CAREFUL  A LOT OF TORQUE IS NOT REQUIRED PISTON DAMAGE CAN OCCUR ID TO MUCH TORQUE IS USED ON THE STOP BOLT** Now **Remove the Flywheel Nut. Use a 3 Jaw Puller and Attach the Puller to the Flywheel. Look for a Puller with Flat Jaws. These Slide Under the Flywheel and Allow for Easier Removal. Tighten the Puller and then Hit the Puller with a Hammer. Tighten and Hit Again Until the Flywheel is Loose and Can be Removed from the Crankshaft. Note the Key that Aligns the Flywheel to the Crankshaft. This Key is Most Likely Sheared or Bent and Causing the Plug to Fire Slightly Out of Time and Causing a Compression Lock. There is Not Enough Compression to Kick Back But Enough to Cause the Engine to Seem to Have High Compression.**  The Threaded Holes in the Flywheel can be Used. These Holes Vary in Size, but are Usually 1/4". From your Description it Sounds like the Flywheel Key has Sheared or the Exhaust Port, Muffler or Spark Arrestor are Clogged with Carbon. If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Thanks.

Respectfully

John