If you are talking about your MT 250 Elsinore, and you are getting a pulsing signal to the coil primary from the Black/White wire, I suspect you may have a stuffed capacitor (condensor). This happens sometimes when the bike has been sitting around in damp conditions for a period of time.
Anyway it's a good starting point as capacitors are cheap.
If that fails to start your rocket, check the continuity of the primary and secondry circuits of the coil.
There isn't a lot more that can go wrong with these babes.
As a final thought! - I don't know if MT 250's have a kill switch. If yours does, there may be a short killing the voltage to the coil, but I suspect not as you say you are getting a pulse to the coil.
Best of luck - and let us know how you get on
cheers
Ray
