Ive got a stihl chain saw model t051 and when you pull cord to start it wont pull on cord like compression is stuck in chamber,but when u remove spark piston stroke is there.What would u say could be fault

NEIL, October 2009

First of all when you remove the plug and pull the cord does gas come out of the cylinder?

Second. The Spark plug could be too long and hitting the piston when the piston comes up. This is most likely the case. Is the gap closed on the plug? If it is then the piston is hitting the spark plug. I use Autolite 255 in my saws without problems.

David Trowbridge, October 2009