I have a 90 cc tomberlin cobra that won't start.
 

It's not the coil,it's new.There's no spark getting to the coil and all ground wires are connected.

3 things to check when trying to get something running

Compression
Fuel
Spark

without one it won't run, you said you're not getting power to the coil, so trace backwards from there. get a test light and follow wires back until you find where it stops giving power.

First off, I have had several new coils and CDIs not work. Brand new out of the box and they were junk. So don't rule out the new coil until your sure.

Second, check the black/red wire at the CDI. See if it has 12v with key on/ignition on. If not keep your volt meter on the black/red wire and switch to AC and crank it over. What is the voltage? Should be higher than 35v and much closer to 80v. If you are getting the right voltage from the stator and you have no spark, then check and make sure ALL cdi pins are tight and nothing is loose. Try having someone crank the motor while you wiggle the wires to the cdi to make sure that their aren't any breaks in the wire. Those are some of the first common things wrong.

Then if you do not have power at the black/red wire check all kill switches. There is a tether switch at the rear of the quad. Make sure it is pushed in and not pulled out. It is a safety kill switch.

If all this is good, I would try a CDI box.

BTW, Could you tell me how you checked for spark? Did you pull the plug and ground it and then crank?