My polaris indy has no spark?

my 1990 polaris indy has no spark i just tested the magneto and got 12-13volts. i put a new cdi on and still no spark. but there is power at the cdi cables that the spark plugs go on to. because when i hold the two wires i feel a strong zapp. i have also tried switching the spark plug boots and nothing. im so confused please help me. maybe its the ground please let me know how to ground the cdi.