Stiga mower won’t run

[Muddy42]

The intake valve wiggle at the end of the motion that you describe is actually a good thing, being the compression release motion of the camshaft.  I'm dealing with an engine with a broken comp release at the moment. But the lifter or crank could be bent, you wont really know unless you take the sump off.  You may have to do this anyway once you are sure the valves are set ok.

 

Its worth spending a fair bit of time to get the valves adjusted properly.  The engine turns counter clockwise when looking from above.  Use a headtorch to see when the piston is at top dead centre, then go on 1/4 inch. I would get a feeler guage. turn the engine over a few times, then check again.

 

Black smoke sounds like the valve seal issue.  But it might clear up on running. You should be able to move the valves in and out a bit by hand, do they all feel the same?