coils

My buddy has a bad coil in his 1978 kz650. Can he use a coil off a 1976kz900ltd on his kz650? Both sets are stock coils. He will replace both coils if they are ok to swap.

do they have the same resistance rating?

I do not know, how would I find out?

it should be marked on them.but if the 650 has points ignition i would think they are the same.

It won't be marked on the coils. Use a multimeter on Ohms scale at the lowest setting (X1 or X10). Put the probes on the two small lugs where the power and ignition connect to the coils. The impedence of the primary windings can be measured like this... you should get about 3.8 Ohms for both coils. Anything in the range of 3.2 to about 5 Ohms will work.