Consecutive low compression in all cylinders could mean that the problem of fuel washed cylinders exists. So, This means that the engine has had too much fuel introduced into it. As a result, all of the oil has been washed off the cylinder walls. The oil creates a sealing effect between the piston and ring assemblies and the cylinder walls of the engine block. This is common with an engine that has a ‘flooding’ problem.
If the engine seems to run normally but is weak and puffs smoke, it could have worn piston rings. In either of these events, squirt a little oil into each cylinder, then repeat the compression test. If the compression dramatically increases then you have found the problem(s). If the compression readings do not change, then it would indicate a timing problem.