Hey,

I've got a 1 cylinder 4 cycle engine that is giving me the following problem:

When the starter cord is pulled, it bangs, and "jumps back". Not sure if it is exactly a back fire, but i can feel the compression in the cylinder kicking back.

If I unplug the spark plus, it stops kicking back, but it still bangs. If I remove the spark plug, it pulls smoothly.

Based on the above, I decided it was a compression issue, probably related to incorrect timing on the valves. The valves seem to be timed OK, though, from what i can tell. They are slightly crooked (i.e. they do not lay quite flush when in the closed position), but I think if that were the problem, I would have a loss of compression, not what I have.

Any suggestions?????

Thanks!

What horsepower and type of engine? sounds like sheared flywheel key to me if your getting pull back on starter cord,also check to see if your blade is loose.

Yep, sheared flywheel key