cb450 revs but does not accelerate

I have a 1981 cb 750 dohc and the timing is off. Cylinder 1/4 is spot on with a strobe light, but 2/3 cannot even be seen. How is this possible? All four cylinders have spark with the plugs laying on the head but the timing is not right. Can anyone point me in a path to start searching other than the step by step process per manual in the ignition section.

make sure it is firing and running on the cylinders in question,ie pipes up front HOT?
one way to eliminate sertin probs is swap coil input power wires as well as plug wires then test check
this will or will not swap over the issue to the other cylinders
check/clean tighten all grounds and wire connections

spark at atmosfear is not same as under cyl pressue good luck one step[ at a time