Small Engines (Lawn Mowers, etc.): 5.5 hp Craftsman lawn mower engine mid to late 90s, blue spark, plug hole

Question
I did a compression test and it was about 86 lbs. Replaced the spark plug, cleaned the carburetor, all the little maintenance thingys.  When I pull to start the engine it makes a metal scraping sound (with the spark plug in) but that same sound goes away when I take the spark plug out and try to pull start it...go figure.  The spark plug has no damage to it, and I can see basic functioning of the engine through the spark plug hole--looks normal to me.  Normal is relative of course.  That compression is probably a little low...but I have a much older Toro lawn mower that registers about 60 lbs and it still runs (not with a whole lot of power but it does run).  I opened the side plate where one can view the valves/aprings...they seemed to work OK too.  I could never get it to start, it was getting a good blue spark, didn't smell as much gas as I thought I would considering the amount of priming I was doing, but I'm pretty sure gas was making it to the cylinder...

Any suggestions for me?

Thanks,  Jason D.


Answer
Hi Jason,

When the engine is under compression, a load is created on whatever is making the scraping sound.  I would guess it's the piston or something in the lower end like the connecting rod.  If it has compression, spark and fuel, it should run though.  I assume that the priming you are doing is with the bulb primer.  If fuel was getting to the cylinder the plug would be wet.  If dry, squirt fuel or starting fluid into the carb intake and try to keep it running for 10 seconds or so.  

Let me know how you make out.
Michael